[Show abstract][Hide abstract] ABSTRACT: Lymphoid tissue immunopathology is a characteristic feature of chronic HIV/SIV infection in AIDS-susceptible species, but is absent in SIV-infected natural hosts. To investigate factors contributing to this difference, we compared germinal center development and SIV RNA distribution in peripheral lymph nodes during primary SIV infection of the natural host sooty mangabey and the non-natural host pig-tailed macaque. Although SIV-infected cells were detected in the lymph node of both species at two weeks post infection, they were confined to the lymph node paracortex in immune-competent mangabeys but were seen in both the paracortex and the germinal center of SIV-infected macaques. By six weeks post infection, SIV-infected cells were no longer detected in the lymph node of sooty mangabeys. The difference in localization and rate of disappearance of SIV-infected cells between the two species was associated with trapping of cell-free virus on follicular dendritic cells and higher numbers of germinal center CD4 T lymphocytes in macaques post SIV infection. Our data suggests that fundamental differences in the germinal center microenvironment prevent productive SIV infection within the lymph node germinal centers of natural hosts contributing to sustained immune competency.
PLoS ONE 01/2013; 8(3):e57785. · 3.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Over a 5-y period, 3 chimpanzees at our institution experienced cerebrovascular accidents (strokes). In light of the increasing population of aged captive chimpanzees and lack of literature documenting the prevalence and effectiveness of various treatments for stroke in chimpanzees, we performed a retrospective review of the medical records and necropsy reports from our institution. A survey was sent to other facilities housing chimpanzees that participate in the Chimpanzee Species Survival Plan to inquire about their experience with diagnosing and treating stroke. This case report describes the presentation, clinical signs, and diagnosis of stroke in 3 recent cases and in historical cases at our institution. Predisposing factors, diagnosis, and treatment options of cerebral vascular accident in the captive chimpanzee population are discussed also.
Comparative medicine 01/2012; 62(4):322-9. · 1.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have evaluated an attenuated Listeria monocytogenes (Lm) candidate vaccine vector in nonhuman primates using a delivery regimen relying solely on oral vaccination. We sought to determine the impact of prior Lm vector exposure on the development of new immune responses against HIV antigens.
Two groups of rhesus macaques one Lm naive, the other having documented prior Lm vector exposures, were evaluated in response to oral inoculations of the same vector expressing recombinant HIV-1 Gag protein. The efficacy of the Lm vector was determined by ELISA to assess the generation of anti-Listerial antibodies; cellular responses were measured by HIV-Gag specific ELISpot assay. Our results show that prior Lm exposures did not diminish the generation of de novo cellular responses against HIV, as compared to Listeria-naïve monkeys. Moreover, empty vector exposures did not elicit potent antibody responses, consistent with the intracellular nature of Lm.
The present study demonstrates in a pre-clinical vaccine model, that prior oral immunization with an empty Lm vector does not diminish immunogenicity to Lm-expressed HIV genes. This work underscores the need for the continued development of attenuated Lm as an orally deliverable vaccine.
Journal of Immune Based Therapies and Vaccines 01/2011; 9:2.
[Show abstract][Hide abstract] ABSTRACT: Sooty mangabeys (Cercocebus atys) are native to West Africa and are a natural host of SIV, which is implicated in the origin of HIV2. They have been used in studies of AIDS pathogenesis, leprosy, immune responses, reproductive biology, and behavior. Spontaneous tumors have rarely been reported in this species. However, we noted spontaneous gastric carcinomas in 8 sooty mangabeys. Four male and 4 female mangabeys had mild to severe chronic weight loss, with abdominal distention in 5 of 8 animals. At necropsy, 7 of the 8 mangabeys had prominent large ulcerated masses with severe, diffuse thickening of the pyloric wall at or near the gastric-duodenal junction, which often partially occluded the gastric lumen. Early carcinoma was an incidental finding in one mangabey. Histologically, all of the tumors were classified as adenocarcinomas. Adenocarcinomas were noncircumscribed with infiltrates of neoplastic epithelial cells, often arranged in acini. In 3 mangabeys, these infiltrates were transmural and invaded surrounding tissue locally. The adenocarcinomas were locally invasive, with metastasis to regional lymph nodes in 2 animals, but widespread metastasis was not seen. Anisocytosis, anisokaryosis, and high mitotic rates were seen in all 8 tumors. In the samples available, serology and Steiner stain did not detect Helicobacter, and immunohistochemistry failed to reveal Helicobacter or Epstein-Barr virus, 2 potential causes for human gastric carcinomas.
Comparative medicine 01/2011; 61(6):527-31. · 1.12 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have developed a major histocompatibility complex-defined primate model of graft-versus-host disease (GVHD) and have determined the effect that CD28/CD40-directed costimulation blockade and sirolimus have on this disease. Severe GVHD developed after haploidentical transplantation without prophylaxis, characterized by rapid clinical decline and widespread T-cell infiltration and organ damage. Mechanistic analysis showed activation and possible counter-regulation, with rapid T-cell expansion and accumulation of CD8(+) and CD4(+) granzyme B(+) effector cells and FoxP3(pos)/CD27(high)/CD25(pos)/CD127(low) CD4(+) T cells. CD8(+) cells down-regulated CD127 and BCl-2 and up-regulated Ki-67, consistent with a highly activated, proliferative profile. A cytokine storm also occurred, with GVHD-specific secretion of interleukin-1 receptor antagonist (IL-1Ra), IL-18, and CCL4. Costimulation Blockade and Sirolimus (CoBS) resulted in striking protection against GVHD. At the 30-day primary endpoint, CoBS-treated recipients showed 100% survival compared with no survival in untreated recipients. CoBS treatment resulted in survival, increasing from 11.6 to 62 days (P < .01) with blunting of T-cell expansion and activation. Some CoBS-treated animals did eventually develop GVHD, with both clinical and histopathologic evidence of smoldering disease. The reservoir of CoBS-resistant breakthrough immune activation included secretion of interferon-γ, IL-2, monocyte chemotactic protein-1, and IL-12/IL-23 and proliferation of cytotoxic T-lymphocyte-associated antigen 4 immunoglobulin-resistant CD28(-) CD8(+) T cells, suggesting adjuvant treatments targeting this subpopulation will be needed for full disease control.
[Show abstract][Hide abstract] ABSTRACT: Opiate abuse increases the risk for human immunodeficiency virus (HIV) infection, while both opiates and HIV may impact the immune and nervous systems. To model potential interactions between opiate drugs and HIV on the brain, neurometabolite levels were evaluated in simian immunodeficiency virus (SIV)-infected macaques with or without chronic morphine administration. Over the course of the study, 58% of these SIV-infected animals progressed to acquired immune deficiency syndrome (AIDS). Brain extracts from four brain regions were evaluated with proton magnetic resonance spectroscopy. Animals with AIDS had lower N-acetyl-aspartate in all four brain regions (p ≤ 0.05) as well as lower frontal gray matter total creatine (p= 0.03), lower frontal white matter (p= 0.003) and caudate (p = 0.002) glutamate, and higher frontal white matter myo-inositol (p= 0.05) than the healthier non-AIDS macaques. Morphine-dependent animals had higher levels of myo-inositol in the putamen (p = 0.003), especially those with AIDS. In the animals with AIDS, those with morphine dependence had higher total creatine in the frontal white matter (p= 0.04) than those treated with saline, which in turn had lower creatine than saline-injected animals without AIDS (p = 0.04), leading to an interaction between the effects of morphine and AIDS on total creatine in this brain region (ANOVA p = 0.02). The majority of these brain metabolites correlated with viral counts indicating more severe metabolite abnormalities in animals with higher viral loads or set points. Collectively, these findings suggest that chronic morphine may protect against the neurotoxic effect of AIDS and reinforce the importance of maintaining a low viral load in AIDS.
Journal of Neuroimmune Pharmacology 10/2010; 6(3):371-80. · 3.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Worldwide, approximately 90% of all human immunodeficiency virus (HIV) transmissions occur mucosally; almost all involve R5 strains. Risks of sexual HIV acquisition are highest for rectal, then vaginal, and finally oral exposures.
Mucosal lacerations may affect the rank order of susceptibility to HIV but cannot be assessed in humans. We measured relative virus transmissibility across intact mucosae in macaques using a single stock of SHIV-1157ipd3N4, a simian-human immunodeficiency virus encoding a primary R5 HIV clade C env (SHIV-C).
The penetrability of rhesus macaque mucosae differed significantly, with rectal challenge requiring the least virus, followed by vaginal and then oral routes (P = .031, oral vs vaginal; P < .001 rectal vs vaginal). These findings imply that intrinsic mucosal properties are responsible for the differential mucosal permeability. The latter paralleled the rank order reported for humans, with relative risk estimates within the range of epidemiological human studies. To test whether inflammation facilitates virus transmission--as predicted from human studies--we established a macaque model of localized buccal inflammation. Systemic infection occurred across inflamed but not normal buccal mucosa.
Our primate data recapitulate virus transmission risks observed in humans, thus establishing R5 SHIV-1157ipd3N4 in macaques as a robust model system to study cofactors involved in human mucosal HIV transmission and its prevention.
The Journal of Infectious Diseases 03/2010; 201(8):1155-63. · 5.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In female squirrel monkeys (Saimiri sciureus), the reproductive period normally extends from approximately 2.5 years to the mid-teens. In the present study, we examined the age-associated cytological changes in the ovaries of 24 squirrel monkeys ranging in age from newborn to approximately 20 years. We found a significant, age-related decline in the number of primordial follicles, with the most pronounced loss occurring between birth and 5 years. After approximately 8 years of age, relatively few primordial follicles were evident in the ovarian sections examined. An unusual feature of the aging squirrel monkey ovary is the emergence of highly differentiated, encapsulated clusters of granulosa cells that increase in size and number, particularly after the age of 8 years. Many of these cells express anti-Müllerian hormone, and, histologically, the clusters resemble granulosa cell tumors in humans. However, granulosa cell clusters (GCCs) are present in both ovaries of all older squirrel monkeys, and they display no obvious signs of malignancy, suggesting that they are a normal feature of ovarian aging in this species. Our findings indicate that reproductive senescence in female squirrel monkeys, as in other primates, involves the inexorable depletion of ovarian follicles. In addition, the consistent appearance of abundant, well-differentiated clusters of granulosa cells in older squirrel monkeys, prior to the cessation of reproduction, suggests that these structures may influence the later stages of reproductive potential in this species. Analysis of GCCs in older squirrel monkeys also could yield insights into the pathophysiology of granulosa cell tumors in humans.
[Show abstract][Hide abstract] ABSTRACT: To determine effects of opiate dependency on development of simian AIDS.
Assessments of viral, immune, and clinicopathological status were conducted on rhesus macaques before and after establishment of opiate dependency and Simian Immunodeficiency Virus, sooty mangabey, strain-9 (SIVsmm9) infection. Controls received saline.
Blood was collected at baseline, before opiate dependencies, and viral infections were established and then after SIVsmm9 infection, longitudinally, through 216 weeks. Plasma viral titers were assessed using the branched chain DNA assay and CD4 and CD8 counts via cytofluorometry. Clinicopathological assessments of AIDS were founded on Centers for Disease Control and Prevention and other selected criteria.
AIDS progression rates seemed to be decelerated and survival times increased by opiate dependency. Mean viral titers were unaffected by opiate exposure. Opiate-dependent monkeys that evidenced high initial viral titers survived significantly longer than controls. Several opiate-dependent monkeys maintained high viral titers for atypically extended durations. Several (5/19) opiate-dependent monkeys died or were removed early from the study due to "non-AIDS" causes.
Long-term opiate dependency seemed to decelerate the rate of progression to AIDS in the SIVsmm9 monkey model. This effect was most evident in monkeys with high initial viral titers/set points. "Non-AIDS" morbidities and mortalities were noted as potential confounds of epidemiological assessments of the role of opiates in HIV/AIDS.
[Show abstract][Hide abstract] ABSTRACT: Studies were undertaken to determine whether previously described reductions in splenic DC-SIGN expression in simian acquired immune deficiency syndrome (AIDS) are limited to pathogenic simian immunodeficiency virus (SIV) infection. DC-SIGN expression was evaluated by immunohistochemistry in lymphoid tissues from AIDS-susceptible Asian macaque monkeys as compared with AIDS-resistant sooty mangabey monkeys in the presence and absence of SIV infection. The phenotype of DC-SIGN+ cells in susceptible and resistant species was identical and most consistent with macrophage identity. Significantly lower levels of DC-SIGN expression were identified in spleen, mesenteric lymph node, and bone marrow of macaques with AIDS (P<0.05). Reduced levels of splenic DC-SIGN correlated significantly with CD4T cell depletion in long-term pathogenic infection of macaques (P<0.01), whereas SIV-infected mangabeys retained high levels of DC-SIGN expression in spleen despite persistent infection. Reduced expression of DC-SIGN in spleen specifically characterizes pathogenic forms of SIV infection, correlates with disease progression, and may contribute to SIV pathogenesis.
[Show abstract][Hide abstract] ABSTRACT: An enigmatic feature of age-related neurodegenerative diseases is that they seldom, if ever, are fully manifested in nonhuman species under natural conditions. The neurodegenerative tauopathies are typified by the intracellular aggregation of hyperphosphorylated microtubule-associated protein tau (MAPT) and the dysfunction and death of affected neurons. We document the first case of tauopathy with paired helical filaments in an aged chimpanzee (Pan troglodytes). Pathologic forms of tau in neuronal somata, neuropil threads, and plaque-like clusters of neurites were histologically identified throughout the neocortex and, to a lesser degree, in allocortical and subcortical structures. Ultrastructurally, the neurofibrillary tangles consisted of tau-immunoreactive paired helical filaments with a diameter and helical periodicity indistinguishable from those seen in Alzheimer's disease. A moderate degree of Abeta deposition was present in the cerebral vasculature and, less frequently, in senile plaques. Sequencing of the exons and flanking intronic regions in the genomic MAPT locus disclosed no mutations that are associated with the known human hereditary tauopathies, nor any polymorphisms of obvious functional significance. Although the lesion profile in this chimpanzee differed somewhat from that in Alzheimer's disease, the copresence of paired helical filaments and Abeta-amyloidosis indicates that the molecular mechanisms for the pathogenesis of the two canonical Alzheimer lesions--neurofibrillary tangles and senile plaques--are present in aged chimpanzees.
The Journal of Comparative Neurology 08/2008; 509(3):259-70. · 3.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In a primate model of postnatal virus transmission, we have previously shown that 1 h post-exposure prophylaxis (PEP) with a triple combination of neutralizing monoclonal antibodies (nmAbs) conferred sterilizing protection to neonatal macaques against oral challenge with pathogenic simian-human immunodeficiency virus (SHIV). Here, we show that nmAbs can also partially protect SHIV-exposed newborn macaques against infection or disease, when given as 12 or 24 h PEP, respectively. This work delineates the potential and the limits of passive immunoprophylaxis with nmAbs. Even though 24 h PEP with nmAbs did not provide sterilizing immunity to neonatal monkeys, it contained viremia and protected infants from acute disease. Taken together with our results from other PEP studies, these data show that the success of passive immunization depends on the nmAb potency/dose and the time window between virus exposure and start of immunotherapy.
[Show abstract][Hide abstract] ABSTRACT: Because milk-borne transmission of human immunodeficiency virus (HIV) diminishes the benefits of perinatal antiviral drug therapy in developing countries, we have developed a new strategy to prevent postnatal and, possibly, intrapartum virus transmission in a primate model. Eight neonatal rhesus macaques were exposed orally to pathogenic simian-human immunodeficiency virus (SHIV); 4 neonates were then given intramuscular postexposure prophylaxis with 3 anti-HIV human neutralizing monoclonal antibodies (nMAbs) with potent cross-clade and cross-group neutralization activity. Untreated infants experienced high viral RNA levels and CD4(+) T-cell losses and died (median survival time, 5.5 weeks). In contrast, all 4 nMAb-treated neonates were protected from infection (P=.028); their plasma, peripheral blood mononuclear cells, and lymph nodes remained virus negative for >1 year. These data are important for designing clinical trials in human neonates and have general implications for AIDS vaccine development, as the epitopes recognized by the 3 nMAbs are conserved among diverse primary isolates.
The Journal of Infectious Diseases 06/2004; 189(12):2167-73. · 5.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Infection of pig-tailed macaques with the simian immunodeficiency virus (SIV) isolate SIVsmmFGb frequently results in SIV encephalitis (SIVE) in addition to immunodeficiency and acquired immune deficiency syndrome. We used in situ hybridization to quantitate the number of SIV-infected cells in brain parenchyma, choroid plexus, and meninges from 17 macaques that developed acquired immune deficiency syndrome after infection with SIVsmmFGb. SIV-infected cells and histopathological lesions of SIVE were identified in 15 of 17 animals (88.2%), including 12 of 12 rapid progressors (RP) and 3 of 5 slow progressors (SP). The parenchymal virus burden was much greater in RP macaques than in the three SP macaques with SIVE (median values of 24.3 versus 0.3 infected cells/mm(2), respectively; P < 0.05). Viral load differences between RP and SP with SIVE were less marked in choroid plexus (29.6 versus 12.8 infected cells/mm(2), respectively) and meninges (133.0 versus 34.2 infected cells/mm(2), respectively). A significant negative correlation was observed between the magnitude of the anti-SIV antibody titer at 1 month after inoculation and brain virus burden at necropsy (r = -0.614; P < 0.01). The close association between immune response and SIVE in this model should prove useful for identifying correlates of immune protection against primate lentiviral encephalitis.
American Journal Of Pathology 04/2004; 164(4):1157-72. · 4.60 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The env gene of three simian immunodeficiency virus (SIV) variants developed convergent mutations during disease progression in six rhesus macaques. The monkeys had been inoculated with supercoiled plasmids encoding infectious proviruses of SIVmac239 (a pathogenic, wild-type strain), SIVdelta3 (the live attenuated vaccine strain derived from SIVmac239), or SIVdelta3+ (a pathogenic progeny virus that had evolved from SIVdelta3). All six monkeys developed immunodeficiency and progressed to fatal disease. Although many divergent mutations arose in env among the different hosts, three regions consistently mutated in all monkeys studied; these similar mutations developed independently even though the animals had received only a single infectious molecular clone rather than standard viral inocula that contain viral quasispecies. Together, these data indicate that the env genes of SIVmac239, SIVdelta3, and SIVdelta3+, in the context of different proviral backbones, evolve similarly in different hosts during disease progression.
[Show abstract][Hide abstract] ABSTRACT: The majority of infants infected through maternal transmission acquire the virus during birth or postpartum through breastfeeding: mucosal exposure is considered to be a major route of infection.
To develop passive immunization with human neutralizing monoclonal antibodies (mAbs) against mother-to-child transmission of HIV during delivery and through breastfeeding.
An oral challenge model in newborn rhesus macaques mimicked peri- and postpartum virus transmission.
Neonatal rhesus macaques were challenged orally with the highly pathogenic, chimeric simian-human immunodeficiency virus SHIV89.6P and given post-exposure prophylaxis with a quadruple combination of neutralizing human mAbs, IgG1b12, 2G12, 2F5, and 4E10, directed against conserved epitopes of HIV envelope glycoproteins. Control animals were virus challenged but left untreated. All infants were followed prospectively for signs of viremia and immunodeficiency.
Two out of four macaque infants treated with neutralizing mAbs showed no evidence of infection; the other two maintained normal CD4 T cell counts. In contrast, all control animals became highly viremic and had profound CD4 T cell losses; three out of four died from AIDS within 1.5-6 weeks of the challenge.
Passive immunization with this quadruple neutralizing mAbs combination may represent a promising approach to prevent peri- and postnatal HIV transmission. Furthermore, the epitopes recognized by the four neutralizing mAbs are key determinants to achieve complete protection and represent important targets against which to develop active, antibody-response-based AIDS vaccines.
[Show abstract][Hide abstract] ABSTRACT: A live attenuated SIV vaccine strain, termed SIVmac239Delta3 and containing large deletions in, and the negative regulatory element, was previously shown to cause AIDS mostly in monkeys vaccinated as infants. In the present study, we demonstrate that SIVmac239Delta3 is pathogenic in most vaccinated adult monkeys, given enough time.
Eleven rhesus macaques vaccinated as adults with SIVmac239Delta3 were followed for extended periods (up to 6.8 years).
We found signs of immune dysregulation in all 11 adult vaccinees. All animals developed persistently inverted CD4 : CD8 T-cell ratios, seven (64%) had persistent recurrent viremia, and six (55%) had decreased CD4 T-cell counts (< 500 x 10 cells/l). Further signs included low CD4CD29 lymphocyte subsets, loss of anti-Gag antibodies, anemia, thrombocytopenia, wasting, and opportunistic infections. Two adult vaccinees (18%) subsequently developed AIDS. Development of chronic, recurrent viremia with plasma viral RNA loads > or = 10 copies/ml and cytoviremia was a poor prognostic sign.
Our data demonstrate that with time, a live attenuated, multiply deleted SIV vaccine can cause immune dysregulation in most vaccine recipients, even in initially immune competent, healthy adults. Immune dysfunction can progress to full AIDS. However, pathogenic effects became evident only several years after vaccination. Thus, mass vaccination of humans with similarly constructed live attenuated HIV vaccines, recently suggested for countries with high HIV-1 transmission rates, seems contraindicated.
[Show abstract][Hide abstract] ABSTRACT: Organ transplant recipients currently require lifetime immunosuppressive therapy, with its accompanying side effects. Biological agents that block T-cell costimulatory pathways are important components of strategies being developed to induce transplantation tolerance. The aim of this study was to test the effect of a novel chimeric anti-human CD40 monoclonal antibody (Chi 220), either alone or in combination with CTLA4-Ig, on the survival of renal allografts in a nonhuman primate model.
Captive-bred adolescent male rhesus monkeys (Macaca mulatta) (4-10 kg) were used as recipients and donors. Four treatment protocols were tested: Chi220 monotherapy, CTLA4-Ig monotherapy, Chi220 combined with CTLA4-Ig, and H106 (anti-CD40L) combined with CTLA4-Ig. Control animals received human albumin. Recipients were followed for survival, renal allograft function as determined by measurement of serum blood urea nitrogen (BUN) and creatinine, chemistries (sodium, potassium, chloride, and bicarbonate), complete blood cell count (CBC) with differential, and the development of donor-specific alloantibody.
Treatment with Chi220 for 14 days prolonged renal allograft survival (MST 38.5 vs. 7 days in untreated controls). Notably, simultaneous blockade of the CD28/B7 pathway did not further augment graft survival but did suppress the development of donor-specific antibodies, an effect not achieved with Chi220 alone, despite peripheral B cell depletion. Finally, treatment with Chi220 suppressed the primary immune response to cytomegalovirus, resulting in severe systemic manifestations.
Blockade of the CD40 pathway with anti-CD40 mAb is immunosuppressive in a large animal, preclinical renal transplant model. The potential effect of this therapy on viral immune responses will be important to consider for the design of safe clinical trials.
[Show abstract][Hide abstract] ABSTRACT: Neonatal rhesus macaque 95-3 was inoculated with nonpassaged simian-human immunodeficiency virus strain SHIV-vpu(+), which encodes env of the laboratory-adapted human immunodeficiency virus (HIV) strain IIIB and is considered nonpathogenic. CD4(+) T-cell counts dropped to <200 cells/microl within 4.6 years, and monkey 95-3 died with opportunistic infections 5.9 years postinoculation. Transfer of blood from 95-3 to two naive adult macaques resulted in high peak viral loads and rapid, persistent T-cell depletion. Progeny virus evolved in 95-3 despite high SHIV-vpu(+) neutralizing antibody titers and still used CXCR4 but, in contrast to parental SHIV-vpu(+), productively infected macrophages and resisted neutralization. Sequence analysis revealed three new potential glycosylation sites in gp120; another two were lost. Strikingly similar mutations were detected in a laboratory worker who progressed to AIDS after accidental HIV-IIIB infection (T. Beaumont et al., J. Virol. 75:2246-2252, 2001), thus supporting the SHIV-vpu(+)/rhesus macaque system as a relevant model. Similar mutations were also described after rapid passage of chimeric viruses encoding IIIB env in rhesus and pig-tailed macaques (M. Cayabyab et al., J. Virol. 73:976-984, 1999; Z. Q. Liu et al., Virology 260:295-307, 1999; S. V. Narayan et al., Virology 256:54-63, 1999; R. Raghavan et al., Brain Pathol. 7:851-861, 1997; E. B. Stephens et al., Virology 231:313-321, 1997). Thus, HIV-IIIB env evolved similarly in three different species; this selection occurred in chronically infected individuals during disease progression as well as after rapid virus passage. We postulate that evolutionary pressure led to the outgrowth of more aggressive viral variants in all three species.
Journal of Virology 05/2002; 76(10):5278-84. · 5.08 Impact Factor