Michael B McChesney

Publications of Michael B McChesney

• Antiviral antibodies and T cells are present in the foreskin of SIV-infected rhesus macaques.

  Authors: Kristina Rothaeusler, Zhong-Min Ma, Huma Qureshi, Timothy D Carroll, Tracy Rourke, Michael B McChesney, Christopher J Miller

  Journal of virology. 04/2012;

  No information exists regarding immune responses to HIV infection in the foreskin or glans of the human penis although this is a key tissue for HIV transmission. To address this gap, we characterizedNo information exists regarding immune responses to HIV infection in the foreskin or glans of the human penis although this is a key tissue for HIV transmission. To address this gap, we characterized antiviral immune responses in foreskin of male rhesus macaques (RM) inoculated with SIVmac251 by penile foreskin exposure. We found a complete population of immune cells in the foreskin and glans of normal RM although B cells were less common than CD4(+) and CD8(+) T cells. IgG secreting cells were detected by ELISPOT in cell suspensions made from the foreskin. In the foreskin and glans of SIV-infected RM although B cells were less common than CD4(+) and CD8(+) T cells, SIV-specific IgG antibody was present in foreskin secretions. In addition, cytokine secreting SIV-specific CD8+ T cells were readily found in cell suspensions made from the foreskin. Although potential HIV target cells were found in and under the epithelium covering all penile surfaces, the presence of antiviral effector B and T cells in the foreskin suggests that vaccines may be able to elicit immunity in this critical site to protect men from acquiring HIV.

• Low-dose penile SIVmac251 exposure of rhesus macaques infected with adenovirus type 5 (Ad5) and then immunized with a replication-defective Ad5-based SIV gag/pol/nef vaccine recapitulates the results of the phase IIb step trial of a similar HIV-1 vaccine.

  Authors: Huma Qureshi, Zhong-Min Ma, Ying Huang, Gregory Hodge, Michael A Thomas, Janet DiPasquale, Veronique DeSilva, Linda Fritts, Andrew J Bett, Danilo R Casimiro, John W Shiver, Marjorie Robert-Guroff, Michael N Robertson, Michael B McChesney, Peter B Gilbert, Christopher J Miller

  Journal of virology. 12/2011; 86(4):2239-50.

  The Step Trial showed that the MRKAd5 HIV-1 subtype B Gag/Pol/Nef vaccine did not protect men from HIV infection or reduce setpoint plasma viral RNA (vRNA) levels but, unexpectedly, it did modestlyThe Step Trial showed that the MRKAd5 HIV-1 subtype B Gag/Pol/Nef vaccine did not protect men from HIV infection or reduce setpoint plasma viral RNA (vRNA) levels but, unexpectedly, it did modestly enhance susceptibility to HIV infection in adenovirus type 5 (Ad5)-seropositive, uncircumcised men. As part of the process to understand the results of the Step Trial, we designed a study to determine whether rhesus macaques chronically infected with a host-range mutant Ad5 (Ad5hr) and then immunized with a replication defective Ad5 SIVmac239 Gag/Pol/Nef vaccine were more resistant or susceptible to SIV infection than unimmunized rhesus macaques challenged with a series of escalating dose penile exposures to SIVmac 251. The Ad5 SIV vaccine induced CD8(+) T cell responses in 70% of the monkeys, which is similar to the proportion of humans that responded to the vaccine in the Step Trial. However, the vaccine did not protect vaccinated animals from penile SIV challenge. At the lowest SIV exposure dose (10(3) 50% tissue culture infective doses), 2 of 9 Ad5-seropositive animals immunized with the Ad5 SIV vaccine became infected compared to 0 of 34 animals infected in the other animal groups (naive animals, Ad5-seropositive animals immunized with the empty Ad5 vector, Ad5-seronegative animals immunized with the Ad5 SIV vaccine, and Ad5-seronegative animals immunized with the empty Ad5 vector). Penile exposure to more concentrated virus inocula produced similar rates of infection in all animal groups. Although setpoint viral loads were unaffected in Step vaccinees, the Ad5 SIV-immunized animals had significantly lower acute-phase plasma vRNA levels compared to unimmunized animals. Thus, the results of the nonhuman primate (NHP) study described here recapitulate the lack of protection against HIV acquisition seen in the Step Trial and suggest a greater risk of infection in the Ad5-seropositive animals immunized with the Ad5 SIV vaccine. Further studies are necessary to confirm the enhancement of virus acquisition and to discern associated mechanisms.

• Alphavirus replicon-based adjuvants enhance the immunogenicity and effectiveness of Fluzone ® in rhesus macaques.

  Authors: Timothy D Carroll, Shannon R Matzinger, Mario Barro, Linda Fritts, Michael B McChesney, Christopher J Miller, Robert E Johnston

  Vaccine. 01/2011; 29(5):931-40.

  Venezuelan equine encephalitis virus replicon particles (VRP) without a transgene (null VRP) have been used to adjuvant effective humoral [1], cellular [2], and mucosal [3] immune responses in mice.Venezuelan equine encephalitis virus replicon particles (VRP) without a transgene (null VRP) have been used to adjuvant effective humoral [1], cellular [2], and mucosal [3] immune responses in mice. To assess the adjuvant activity of null VRP in the context of a licensed inactivated influenza virus vaccine, rhesus monkeys were immunized with Fluzone(®) alone or Fluzone(®) mixed with null VRP and then challenged with a human seasonal influenza isolate, A/Memphis/7/2001 (H1N1). Compared to Fluzone(®) alone, Fluzone(®)+null VRP immunized animals had stronger influenza-specific CD4(+) T cell responses (4.4 fold) with significantly higher levels of virus-specific IFN-γ (7.6 fold) and IL-2 (5.3 fold) producing CD4+ T cells. Fluzone(®)+null VRP immunized animals also had significantly higher plasma anti-influenza IgG (p<0.0001, 1.3 log) and IgA (p<0.05, 1.2 log) levels. In fact, the mean plasma anti-influenza IgG titers after one Fluzone(®)+null VRP immunization was 1.2 log greater (p<0.04) than after two immunizations with Fluzone(®) alone. After virus challenge, only Fluzone(®)+null VRP immunized monkeys had a significantly lower level of viral replication (p<0.001) relative to the unimmunized control animals. Although little anti-influenza antibody was detected in the respiratory secretions after immunization, strong anamnestic anti-influenza IgG and IgA responses were present in secretions of the Fluzone(®)+null VRP immunized monkeys immediately after challenge. There were significant inverse correlations between influenza RNA levels in tracheal lavages and plasma anti-influenza HI and IgG anti-influenza antibody titers prior to challenge. These results demonstrate that null VRP dramatically improve both the immunogenicity and protection elicited by a licensed inactivated influenza vaccine.

• Exogenous IFN-alpha administration reduces influenza A virus replication in the lower respiratory tract of rhesus macaques.

  Authors: Shannon R Matzinger, Timothy D Carroll, Linda Fritts, Michael B McChesney, Christopher J Miller

  PloS one. 01/2011; 6(12):e29255.

  To determine the role of innate immune responses in controlling influenza A virus replication, rhesus macaques (RM) were administered pegylated IFN-alpha prior to virus challenge. Systemic andTo determine the role of innate immune responses in controlling influenza A virus replication, rhesus macaques (RM) were administered pegylated IFN-alpha prior to virus challenge. Systemic and mucosal pegylated IFN-alpha administration induced expression of the interferon-stimulated genes (ISG) MxA and OAS in the airways. RM treated with IFN-alpha 24 hours prior to influenza virus challenge had significantly lower peak vRNA levels in the trachea compared to untreated animals. In addition to blunting viral replication, IFN-alpha treatment minimized the weight loss and spike in body temperature after influenza infection of RM. These results confirm the importance of IFN-alpha induced innate immune responses in the rapid control of influenza A virus replication in primates.

• Memory B cells and CD8⁺ lymphocytes do not control seasonal influenza A virus replication after homologous re-challenge of rhesus macaques.

  Authors: Timothy D Carroll, Shannon R Matzinger, Linda Fritts, Michael B McChesney, Christopher J Miller

  PloS one. 01/2011; 6(6):e21756.

  This study sought to define the role of memory lymphocytes in the protection from homologous influenza A virus re-challenge in rhesus macaques. Depleting monoclonal antibodies (mAb) were administeredThis study sought to define the role of memory lymphocytes in the protection from homologous influenza A virus re-challenge in rhesus macaques. Depleting monoclonal antibodies (mAb) were administered to the animals prior to their second experimental inoculation with a human seasonal influenza A virus strain. Treatment with either anti-CD8α or anti-CD20 mAbs prior to re-challenge had minimal effect on influenza A virus replication. Thus, in non-human primates with pre-existing anti-influenza A antibodies, memory B cells and CD8α⁺ T cells do not contribute to the control of virus replication after re-challenge with a homologous strain of influenza A virus.

• A recombinant measles virus unable to antagonize STAT1 function cannot control inflammation and is attenuated in rhesus monkeys.

  Authors: Patricia Devaux, Andrew W Hudacek, Gregory Hodge, Jorge Reyes-Del Valle, Michael B McChesney, Roberto Cattaneo

  Journal of virology. 10/2010; 85(1):348-56.

  Measles remains a leading cause of death worldwide among children because it suppresses immune function. The measles virus (MV) P gene encodes three proteins (P, V, and C) that interfere with innateMeasles remains a leading cause of death worldwide among children because it suppresses immune function. The measles virus (MV) P gene encodes three proteins (P, V, and C) that interfere with innate immunity, controlling STAT1, STAT2, mda5, and perhaps other key regulators of immune function. We identified here three residues in the shared domain of the P and V proteins-tyrosine 110, valine 112, and histidine 115-that function to retain STAT1 in the cytoplasm and inhibit interferon transcription. This information was used to generate a recombinant measles virus unable to antagonize STAT1 function (STAT1-blind MV) differing only in these three residues from a wild-type strain of well-defined virulence. This virus was used to assess the relevance of P and V interactions with STAT1 for virulence in primates. When a group of six rhesus monkeys (Macaca mulatta) was inoculated intranasally with STAT1-blind MV, viremia was short-lived, and the skin rash and other clinical signs observed with wild-type MV were absent. The STAT1-blind virus less efficiently controlled the inflammatory response, as measured by enhanced transcription of interleukin-6 and tumor necrosis factor alpha in peripheral blood mononuclear cells from infected hosts. Importantly, neutralizing antibody titers and MV-specific T-cell responses were equivalent in hosts infected with either virus. These findings indicate that efficient MV interactions with STAT1 are required to sustain virulence in a natural host by controlling the inflammatory response against the virus. They also suggest that selectively STAT1-blind MV may have utility as vectors for targeted oncolysis and vaccination.

• Measles virus selectively blind to signaling lymphocytic activation molecule (SLAM; CD150) is attenuated and induces strong adaptive immune responses in rhesus monkeys.

  Authors: Vincent H J Leonard, Gregory Hodge, Jorge Reyes-Del Valle, Michael B McChesney, Roberto Cattaneo

  Journal of virology. 04/2010; 84(7):3413-20.

  The signaling lymphocytic activation molecule (SLAM; CD150) is the immune cell receptor for measles virus (MV). To assess the importance of the SLAM-MV interactions for virus spread and pathogenesis,The signaling lymphocytic activation molecule (SLAM; CD150) is the immune cell receptor for measles virus (MV). To assess the importance of the SLAM-MV interactions for virus spread and pathogenesis, we generated a wild-type IC-B MV selectively unable to recognize human SLAM (SLAM-blind). This virus differs from the fully virulent wild-type IC-B strain by a single arginine-to-alanine substitution at amino acid 533 of the attachment protein hemagglutinin and infects cells through SLAM about 40 times less efficiently than the isogenic wild-type strain. Ex vivo, this virus infects primary lymphocytes at low levels regardless of SLAM expression. When a group of six rhesus monkeys (Macaca mulatta) was inoculated intranasally with the SLAM-blind virus, no clinical symptoms were documented. Only one monkey had low-level viremia early after infection, whereas all the hosts in the control group had high viremia levels. Despite minimal, if any, viremia, all six hosts generated neutralizing antibody titers close to those of the control monkeys while MV-directed cellular immunity reached levels at least as high as in wild-type-infected monkeys. These findings prove formally that efficient SLAM recognition is necessary for MV virulence and pathogenesis. They also suggest that the selectively SLAM-blind wild-type MV can be developed into a vaccine vector.

• Depo-provera treatment does not abrogate protection from intravenous SIV challenge in female macaques immunized with an attenuated AIDS virus.

  Authors: Meritxell Genescà, Michael B McChesney, Christopher J Miller

  PloS one. 01/2010; 5(3):e9814.

  In a previous study, progesterone treatment of female monkeys immunized with live, attenuated SHIV89.6 abrogated the generally consistent protection from vaginal simian immunodeficiency virus (SIV)In a previous study, progesterone treatment of female monkeys immunized with live, attenuated SHIV89.6 abrogated the generally consistent protection from vaginal simian immunodeficiency virus (SIV) challenge. The mechanisms responsible for the loss of protection remain to be defined. The objective of the present study was to determine whether Depo-Provera administration alters protection from intravenous SIV challenge in SHIV-immunized female macaques. Two groups of female macaques were immunized with attenuated SHIV89.6 and then challenged intravenously with SIVmac239. Four weeks before challenge, one animal group was treated with Depo-Provera, a commonly used injectable contraceptive progestin. As expected, SHIV-immunized monkeys had significantly lower peak and set-point plasma viral RNA levels compared to naïve controls, but in contrast to previously published findings with vaginal SIV challenge, the Depo-Provera SHIV-immunized animals controlled SIV replication to a similar, or even slightly greater, degree than did the untreated SHIV-immunized animals. Control of viral replication from week 4 to week 20 after challenge was more consistent in the progesterone-treated, SHIV-immunized animals than in untreated, SHIV-immunized animals. Although levels of interferon-gamma production were similar, the SIV-specific CD8(+) T cells of progesterone-treated animals expressed more functions than the anti-viral CD8(+) T cells from untreated animals. Depo-Provera did not diminish the control of viral replication after intravenous SIV challenge in female macaques immunized with a live-attenuated lentivirus. This result contrasts with the previously reported effect of Depo-Provera(R) on protection from vaginal SIV challenge and strongly implies that the decreased protection from vaginal challenge is due to effects of progesterone on the genital tract rather than to systemic effects. Further, these results demonstrate that the effects of hormonal contraceptives on vaccine efficacy need to be considered in the context of testing and use of an AIDS vaccine.

• Limited dissemination of pathogenic SIV after vaginal challenge of rhesus monkeys immunized with a live, attenuated lentivirus.

  Authors: Mars Stone, Zhong-Min Ma, Meritxell Genescà, Linda Fritts, Shelley Blozois, Michael B McChesney, Christopher J Miller

  Virology. 08/2009;

  In non-human primate models of AIDS, attenuated lentiviruses provide the most reliable protection from challenge with pathogenic virus but the extent to which the vaccine virus replicates afterIn non-human primate models of AIDS, attenuated lentiviruses provide the most reliable protection from challenge with pathogenic virus but the extent to which the vaccine virus replicates after challenge is unclear. At 7 and 14 days after vaginal challenge with pathogenic SIVmac239, plasma SIVenv RNA levels were significantly lower in female macaques immunized 6 months earlier with live, attenuated SHIV89.6 compared to unimmunized control animals. In 2 SHIV-immunized, unprotected macaques SIV replication produced moderate-level plasma viremia with dissemination of challenge virus to all tissues on day 14 after challenge. In protected, SHIV-immunized monkeys, SIV replication was controlled in all tissues, from the day of challenge through 14 days post-challenge. Further, in CD8(+) T cell-depleted SHIV-immunized animals, SIV replication and dissemination were more rapid than in control animals. These findings suggest that replication of a pathogenic AIDS virus can be controlled at the site of mucosal inoculation by live-attenuated lentivirus immunization.

• Protective anti-hepatitis B responses in Rhesus monkeys primed with a vectored measles virus and boosted with a single hepatitis B surface antigen dose.

  Authors: Jorge Reyes-Del Valle, Gregory Hodge, Michael B McChesney, Roberto Cattaneo

  Journal of virology. 07/2009;

  The widely used hepatitis B virus (HBV) vaccine is based on three doses of hepatitis B surface antigen (HBsAg) protein. We previously showed that vectored measles viruses (MV) expressing HBsAg retainThe widely used hepatitis B virus (HBV) vaccine is based on three doses of hepatitis B surface antigen (HBsAg) protein. We previously showed that vectored measles viruses (MV) expressing HBsAg retain measles vaccine function in monkeys, but do not induce a protective anti-HBs response in all animals. We show here that a single HBsAg protein dose following a three dose vaccination regimen with an optimized HBsAg-expressing MV elicits protective anti-HBs responses in all four vaccinated Rhesus monkeys. Vaccination strategies coupling the effective, long-term immunity elicited by the high coverage MV vaccine to prophylactic HBV immunity are discussed.

• With minimal systemic T cell expansion, CD8+ T cells mediate protection from vaginal SIV challenge in rhesus macaques immunized with attenuated SHIV89.6.

  Authors: Meritxell Genescà, Pamela J Skinner, Jung Joo Hong, Jun Li, Ding Lu, Michael B McChesney, Christopher J Miller

  Journal of virology. 10/2008;

  The presence, at the time of challenge, of antiviral effector T cells in the vaginal mucosa of female rhesus macaques immunized with live-attenuated simian-human immunodeficiency virus (SHIV) 89.6 isThe presence, at the time of challenge, of antiviral effector T cells in the vaginal mucosa of female rhesus macaques immunized with live-attenuated simian-human immunodeficiency virus (SHIV) 89.6 is associated with consistent and reproducible protection from pathogenic simian immunodeficiency virus (SIV) vaginal challenge (18). Here we definitively demonstrate the protective role of the SIV-specific CD8(+) T cell response in the SHIV-immunized monkeys by CD8(+) lymphocyte depletion, an intervention that abrogated SHIV-mediated control of challenge virus replication and largely eliminated the SIV-specific T cell responses in blood lymph nodes and genital mucosa. While in the T cell intact SHIV- immunized animals, polyfunctional and degranulating SIV-specific CD8(+) T cells were present in the genital tract and lymphoid tissues from the day of challenge until day 14 post-challenge. Strikingly, expansion of SIV-specific CD8(+) T cells in the immunized monkeys was minimal and limited to the vagina. Thus, protection from uncontrolled SIV replication in animals immunized with attenuated SHIV 89.6 is primarily mediated by CD8(+) T cells that do not undergo dramatic systemic expansion after SIV challenge. These findings demonstrate that despite, and perhaps because of, minimal systemic expansion of T cells at the time of challenge, a stable population of effector-cytotoxic CD8(+) T cells can provide significant protection from vaginal SIV challenge.

• Measles virus blind to its epithelial cell receptor remains virulent in rhesus monkeys but cannot cross the airway epithelium and is not shed.

  Authors: Vincent H J Leonard, Patrick L Sinn, Gregory Hodge, Tanner Miest, Patricia Devaux, Numan Oezguen, Werner Braun, Paul B McCray, Michael B McChesney, Roberto Cattaneo

  The Journal of clinical investigation. 08/2008; 118(7):2448-2458.

  The current model of measles virus (MV) pathogenesis implies that apical infection of airway epithelial cells precedes systemic spread. An alternative model suggests that primarily infected lymphaticThe current model of measles virus (MV) pathogenesis implies that apical infection of airway epithelial cells precedes systemic spread. An alternative model suggests that primarily infected lymphatic cells carry MV to the basolateral surface of epithelial cells, supporting MV shedding into the airway lumen and contagion. This model predicts that a mutant MV, unable to enter cells through the unidentified epithelial cell receptor (EpR), would remain virulent but not be shed. To test this model, we identified residues of the MV attachment protein sustaining EpR-mediated cell fusion. These nonpolar or uncharged polar residues defined an area located near the binding site of the signaling lymphocytic activation molecule (SLAM), the receptor for MV on lymphatic cells. We then generated an EpR-blind virus maintaining SLAM-dependent cell entry and inoculated rhesus monkeys intranasally. Hosts infected with the selectively EpR-blind MV developed rash and anorexia while averaging slightly lower viremia than hosts infected with wild-type MV but did not shed virus in the airways. The mechanism restricting shedding was characterized using primary well-differentiated human airway epithelial cells. Wild-type MV infected columnar epithelial cells bearing tight junctions only when applied basolaterally, while the EpR-blind virus did not infect these cells. Thus, EpR is probably a basolateral protein, and infection of the airway epithelium is not essential for systemic spread and virulence of MV.

• Personality and serotonin transporter genotype interact with social context to affect immunity and viral set-point in simian immunodeficiency virus disease.

  Authors: John P Capitanio, Kristina Abel, Sally P Mendoza, Shelley A Blozis, Michael B McChesney, Steve W Cole, William A Mason

  Brain, behavior, and immunity. 08/2008; 22(5):676-89.

  From the beginning of the AIDS epidemic, stress has been a suspected contributor to the wide variation seen in disease progression, and some evidence supports this idea. Not all individuals respondFrom the beginning of the AIDS epidemic, stress has been a suspected contributor to the wide variation seen in disease progression, and some evidence supports this idea. Not all individuals respond to a stressor in the same way, however, and little is known about the biological mechanisms by which variations in individuals' responses to their environment affect disease-relevant immunologic processes. Using the simian immunodeficiency virus/rhesus macaque model of AIDS, we explored how personality (Sociability) and genotype (serotonin transporter promoter) independently interact with social context (Stable or Unstable social conditions) to influence behavioral expression, plasma cortisol concentrations, SIV-specific IgG, and expression of genes associated with Type I interferon early in infection. SIV viral RNA set-point was strongly and negatively correlated with survival as expected. Set-point was also associated with expression of interferon-stimulated genes, with CXCR3 expression, and with SIV-specific IgG titers. Poorer immune responses, in turn, were associated with display of sustained aggression and submission. Personality and genotype acted independently as well as in interaction with social condition to affect behavioral responses. Together, the data support an "interactionist" perspective [Eysenck, H.J., 1991. Personality, stress and disease: an interactionist perspective. Psychol. Inquiry 2, 221-232] on disease. Given that an important goal of HIV treatment is to maintain viral set-point as low as possible, our data suggest that supplementing anti-retroviral therapy with behavioral or pharmacologic modulation of other aspects of an organism's functioning might prolong survival, particularly among individuals living under conditions of threat or uncertainty.

• Attenuation of V- or C-defective measles viruses: infection control by the inflammatory and interferon responses of rhesus monkeys.

  Authors: Patricia Devaux, Gregory Hodge, Michael B McChesney, Roberto Cattaneo

  Journal of virology. 07/2008; 82(11):5359-67.

  Patients recruited in virus-based cancer clinical trials and immunocompromised individuals in need of vaccination would profit from viral strains with defined attenuation mechanisms. We generatedPatients recruited in virus-based cancer clinical trials and immunocompromised individuals in need of vaccination would profit from viral strains with defined attenuation mechanisms. We generated measles virus (MV) strains defective for the expression of either the V protein, a modulator of the innate immune response, or the C protein, which has multiple functions. The virulence of these strains was compared with that of the parental wild-type MV in a natural host, Macaca mulatta. Skin rash, viremia, and the strength of the innate and adaptive immune responses were characterized in groups of six animals. Replication of V- or C-protein-defective viruses was short-lived and reached lower levels in peripheral blood mononuclear cells and lymphatic organs compared to the wild-type virus; none of the mutants reverted to the wild type. The neutralizing antibody titers and MV-specific T-cell responses were equivalent in monkeys infected with the viral strains tested, documenting strong adaptive immune responses. In contrast, the inflammatory response was better controlled by wild-type MV, as revealed by inhibition of interleukin-6 and tumor necrosis factor alpha transcription. The interferon response was also better controlled by the wild-type virus than by the defective viruses. Since V- and C-defective MVs induce strong adaptive immune responses while spreading less efficiently, they may be developed as vaccines for immunocompromised individuals. Moreover, MV unable to interact with single innate immunity proteins may be developed for preferential replication in tumors with specific contexts of vulnerability.

• Genetic changes that affect the virulence of measles virus in a rhesus macaque model.

  Authors: Bettina Bankamp, Gregory Hodge, Michael B McChesney, William J Bellini, Paul A Rota

  Virology. 04/2008; 373(1):39-50.

  To identify genetic changes that lead to the attenuation of measles virus (MV), a strain of MV that is pathogenic in rhesus macaques was adapted to grow in Vero cells, Vero/hSLAM cells and, toTo identify genetic changes that lead to the attenuation of measles virus (MV), a strain of MV that is pathogenic in rhesus macaques was adapted to grow in Vero cells, Vero/hSLAM cells and, to simulate the process used to derive live attenuated vaccines, in primary chicken embryo fibroblasts (CEF). Comparison of the complete genomic sequences of the pathogenic wild-type (Davis87-wt) and four cell culture-adapted strains derived from it showed complete conservation of sequence in the Vero/hSLAM-passaged virus. Viruses adapted to Vero cells and CEF had predicted amino acid changes in the nucleocapsid protein, phosphoprotein, V protein, C protein, matrix protein, and the cytoplasmic tail of the hemagglutinin protein. All four cell culture-adapted strains, including the Vero/hSLAM cell-passaged virus, were able to productively infect Vero cells, but the peak viral titers differed. The Vero cell-adapted strains were unable to replicate in Chinese Hamster Ovary cells expressing CD46, indicating that they had not adapted to use the CD46 receptor. The Vero/hSLAM cell-passaged virus retained pathogenicity in rhesus macaques as measured by the appearance of a skin rash while the Vero cell-adapted and CEF-adapted strains had lost the ability to cause a rash. There were no significant differences in viral titers in peripheral blood mononuclear cells among monkeys infected with any of the viral stocks tested. These results identify a limited number of genetic changes in the genome of MV that lead to attenuation in vivo.

• Interferon-induced expression of MxA in the respiratory tract of rhesus macaques is suppressed by influenza virus replication.

  Authors: Timothy D Carroll, Shannon R Matzinger, Meritxell Genescà, Linda Fritts, Roxana Colòn, Michael B McChesney, Christopher J Miller

  Journal of immunology (Baltimore, Md. : 1950). 02/2008; 180(4):2385-95.

  To determine the relationship between influenza A virus replication and innate antiviral immune responses, rhesus monkeys were given oseltamivir before influenza A/Memphis/7/01 (H1N1) challenge. WeTo determine the relationship between influenza A virus replication and innate antiviral immune responses, rhesus monkeys were given oseltamivir before influenza A/Memphis/7/01 (H1N1) challenge. We found that oseltamivir treatment significantly reduced viral replication in the trachea (p < 0.029). Further, in the trachea of both treated and untreated monkeys the mRNA levels of most innate antiviral molecules in the IFN-alphabeta pathway were dramatically increased by 24 h postinfection. However, the mRNA level of a single IFN-stimulated gene, MxA (myxovirus resistance A), the IFN-stimulated gene known to be critical in blocking influenza virus replication, was significantly lower in the tracheal lavages of untreated monkeys than in the oseltamivir-treated monkeys (p = 0.05). These results demonstrate for the first time that uncontrolled influenza A virus replication actively suppresses MxA gene expression and emphasize the critical role of innate immunity in controlling influenza virus replication in vivo.

• Live attenuated lentivirus infection elicits polyfunctional simian immunodeficiency virus Gag-specific CD8+ T cells with reduced apoptotic susceptibility in rhesus macaques that control virus replication after challenge with pathogenic SIVmac239.

  Authors: Meritxell Genescà, Tracy Rourke, Jun Li, Kristen Bost, Barinderpaul Chohan, Michael B McChesney, Christopher J Miller

  Journal of immunology (Baltimore, Md. : 1950). 11/2007; 179(7):4732-40.

  HIV-specific CD8+ T cells that secrete multiple cytokines in response to Ag stimulation are associated with the control of virus replication during chronic HIV infection. To determine whether theHIV-specific CD8+ T cells that secrete multiple cytokines in response to Ag stimulation are associated with the control of virus replication during chronic HIV infection. To determine whether the presence of polyfunctional CD8+ T cell responses distinguishes protected and unprotected monkeys in a live attenuated lentivirus model, SIV Gag peptide-specific CD8+ T cell responses of simian HIV (SHIV) 89.6-vaccinated, SIVmac239-challenged rhesus macaques were compared in two monkeys that controlled challenge virus replication and two that did not. The ratio of Bcl-2+ Gag-specific CD8+ T cells to caspase-3+ Gag-specific CD8+ T cells was higher in the vaccinated-protected animals compared with unprotected monkeys. In addition, polyfunctional SIV-specific CD8+ T cells were consistently detected through 12 wk postchallenge in the protected animals but not in the unprotected animals. In the unprotected monkeys, there was an increased frequency of CD8+ T cells expressing markers associated with effector memory T cells. Further, there was increased annexin V expression in central memory T cells of the unprotected animals before challenge. Thus, monkeys that control viral replication after live attenuated SHIV infection have polyfunctional SIV-specific CD8+ T cells with an increased survival potential. Importantly, the differences in the nature of the SIV-specific CD8+ T cell response in the protected and unprotected animals are present during acute stages postchallenge, before different antigenic levels are established. Thus, the polyfunctional capacity and increased survival potential of CD8+ SIV-specific T cells may account for live attenuated, SHIV89.6-mediated protection from uncontrolled SIV replication.

• A vectored measles virus induces hepatitis B surface antigen antibodies while protecting macaques against measles virus challenge.

  Authors: Jorge Reyes-Del Valle, Patricia Devaux, Gregory Hodge, Nicholas J Wegner, Michael B McChesney, Roberto Cattaneo

  Journal of virology. 11/2007; 81(19):10597-605.

  Hepatitis B virus (HBV) acute and chronic infections remain a major worldwide health problem. Towards developing an anti-HBV vaccine with single-dose scheme potential, we engineered infectiousHepatitis B virus (HBV) acute and chronic infections remain a major worldwide health problem. Towards developing an anti-HBV vaccine with single-dose scheme potential, we engineered infectious measles virus (MV) genomic cDNAs with a vaccine strain background and expression vector properties. Hepatitis B surface antigen (HBsAg) expression cassettes were inserted into this cDNA and three MVs expressing HBsAg at different levels generated. All vectored MVs, which secrete HBsAg as subviral particles, elicited humoral responses in MV-susceptible genetically modified mice. However, small differences in HBsAg expression elicited vastly different HBsAg antibody levels. The two vectors inducing the highest HBsAg antibody levels were inoculated into rhesus monkeys (Macaca mulatta). After challenge with a pathogenic MV strain (Davis87), control naive monkeys showed a classic measles rash and high viral loads. In contrast, all monkeys immunized with vaccine or a control nonvectored recombinant vaccine or HBsAg-expressing vectored MV remained healthy, with low or undetectable viral loads. After a single vaccine dose, only the vector expressing HBsAg at the highest levels elicited protective levels of HBsAg antibodies in two of four animals. These observations reveal an expression threshold for efficient induction of HBsAg humoral immune responses. This threshold is lower in mice than in macaques. Implications for the development of divalent vaccines based on live attenuated viruses are discussed.

• Depo-Provera abrogates attenuated lentivirus-induced protection in male rhesus macaques challenged intravenously with pathogenic SIVmac239.

  Authors: Meritxell Genescà, Jun Li, Linda Fritts, Paul Chohan, Kristen Bost, Tracy Rourke, Shelley A Blozis, Michael B McChesney, Christopher J Miller

  Journal of medical primatology. 09/2007; 36(4-5):266-75.

  BACKGROUND: Progesterone administration prior to intravaginal challenge with pathogenic SIVmac239 decreases the protective efficacy of live attenuated vaccines in rhesus macaques. METHODS: ToBACKGROUND: Progesterone administration prior to intravaginal challenge with pathogenic SIVmac239 decreases the protective efficacy of live attenuated vaccines in rhesus macaques. METHODS: To determine if progesterone alters the efficacy of live attenuated vaccines through local or systemic effects, seven male rhesus macaques were immunized with SHIV89.6 and then challenged intravenously with SIVmac239. Three of these animals were treated with Depo-Provera 30 days prior to the SIV challenge. RESULTS: The SHIV animals had significantly lower plasma viral RNA levels than the unimmunized control monkeys, but the Depo-Provera treated, SHIV-immunized animals did not. Despite the lack of protection, the Depo-Provera SHIV animals had strong SIV specific T-cell responses. However, altered patterns of NK frequency and CD38 T-cell expression prior to SIV challenge were observed in Depo-Provera SHIV animals. CONCLUSIONS: Depo-Provera eliminates live-attenuated lentivirus vaccine efficacy in male rhesus monkeys through systemic effects on antiviral immunity and/or viral replication.

• Pseudotyped single-cycle simian immunodeficiency viruses expressing gamma interferon augment T-cell priming responses in vitro.

  Authors: Yue Peng, Fan-Ching Lin, Paulo H Verardi, Leslie A Jones, Michael B McChesney, Tilahun D Yilma

  Journal of virology. 04/2007; 81(5):2187-95.

  To increase the safety and efficacy of human immunodeficiency virus vaccines, several groups have conducted studies using the macaque model with single-cycle replicating simian immunodeficiencyTo increase the safety and efficacy of human immunodeficiency virus vaccines, several groups have conducted studies using the macaque model with single-cycle replicating simian immunodeficiency viruses (SIVs). However, these constructs had poor or diminished efficacy compared to live attenuated vaccines. We previously showed that immunization of macaques with live attenuated SIV with a deletion in the nef gene and expressing gamma interferon (IFN-gamma) results in significantly enhanced safety and efficacy. To further enhance safety, we constructed and characterized single-cycle SIVs, pseudotyped with the glycoprotein of vesicular stomatitis virus, expressing different levels of macaque IFN-gamma. Expression of IFN-gamma did not alter the infectivity or antigenicity of pseudotyped SIV. The transduction of dendritic cells (DCs) by IFN-gamma-expressing particles resulted in the up-regulation of costimulatory and major histocompatibility complex molecules. Furthermore, T cells primed with DCs transduced by SIV particles expressing high levels of IFN-gamma and then stimulated with SIV induced significantly higher numbers of spot-forming cells in an enzyme-linked immunospot assay than did T cells primed with DCs transduced with SIV particles lacking the cytokine. In conclusion, we demonstrated that the transduction of DCs in vitro with pseudotyped single-cycle SIVs expressing IFN-gamma increased DC activation and augmented T-cell priming activity.