Suryaprakash Sambhara

University of Washington Seattle, Seattle, Washington, United States

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Publications (69)450.65 Total impact

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    ABSTRACT: The NLR protein, NLRC5, is an important regulator of MHC I gene expression, however, the role of NLRC5 in other innate immune responses is less well defined. In the present study, we report that NLRC5 binds RIG-I and that this interaction is critical for robust antiviral responses against influenza virus. Overexpression of NLRC5 in the human lung epithelial cell line, A549, and normal human bronchial epithelial (NHBE) cells resulted in impaired replication of influenza virus A/Puerto Rico/8/34 virus (PR8) and enhanced IFN-β expression. Influenza virus leads to induction of IFN-β that drives RIG-I and NLRC5 expression in host cells. Our results suggest that NLRC5 extends and stabilizes influenza virus-induced RIG-I expression and delays expression of the viral inhibitor protein NS1. We show that NS1 binds to NLRC5 to suppress its function. Interaction domain mapping revealed that NLRC5 interacts with RIG-I via its N-terminal death domain and that NLRC5 enhanced antiviral activity in a LRR-domain-independent manner. Taken together, our findings identify a novel role for NLRC5 in RIG-I-mediated antiviral host responses against influenza virus infection, distinguished from the role of NLRC5 in MHC class I gene regulation.This article is protected by copyright. All rights reserved
    European Journal of Immunology 11/2014; 45(3). DOI:10.1002/eji.201344412 · 4.52 Impact Factor
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    ABSTRACT: Pattern Recognition Receptors (PRR) sense certain molecular patterns uniquely expressed by pathogens. Retinoic-acid-inducible gene I (RIG-I) is a cytosolic PRR that senses viral nucleic acids and induces innate immune activation and secretion of type-I IFNs. Here, using influenza vaccine antigens, we investigated the consequences of activating the RIG-I pathway on antigen-specific adaptive immune responses. We found that mice immunized with influenza vaccine antigens co-administered with 5' ppp-dsRNA, a RIG-I ligand, developed robust levels of hemagglutination inhibiting antibodies, enhanced germinal center reaction and T follicular helper cell responses. In addition, RIG-I activation enhanced antibody affinity maturation and plasma cell responses in draining lymph nodes, spleen, and bone marrow and conferred protective immunity against virus challenge. Importantly, activation of RIG-I pathway was able to reduce the antigen requirement by 10-100 folds in inducing optimal influenza-specific cellular and humoral responses including protective immunity. The effects induced by 5' ppp-dsRNA were significantly dependent on type-I IFN and IPS-1 (adapter protein downstream of RIG-I pathway) signaling, but were independent of MyD88 or TLR3 mediated pathways. Our results show that activation of RIG-I-like receptor pathway programs the innate immunity to achieve qualitatively and quantitatively enhanced protective cellular adaptive immune responses even at low antigen doses and thus, indicate the potential utility of RIG-I ligands as molecular adjuvants for the viral vaccines.
    Journal of Virology 09/2014; In Press. DOI:10.1128/JVI.02273-14 · 4.65 Impact Factor
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    ABSTRACT: Influenza A virus (IAV), like other viruses, exploits the machinery of human host cells for its survival and replication. We identified α-actinin-4, a host cytoskeletal protein, as an interacting partner of IAV nucleoprotein (NP). We confirmed this interaction using co-immunoprecipitation studies first in coupled in-vitro transcription-translation assay and then in cells either transiently co-expressing the two proteins or infected with whole IAV. Importantly, the NP-actinin-4 interaction was observed in several IAV subtypes including the 2009 H1N1 pandemic virus. Moreover, immunofluorescence studies revealed that both NP and actinin-4 co-localized largely around the nucleus and also in the cytoplasmic region of virus-infected A549 cells. Silencing of actinin-4 expression resulted in not only a significant decrease in NP, M2 and NS1 viral protein expression but also reduction of both, NP mRNA and vRNA levels as well as viral titers, 24 hr post-infection with Influenza A virus, suggesting that actinin-4 was critical for viral replication. Furthermore, actinin-4 depletion reduced the amount of NP localized in the nucleus. Treatment of infected cells with wortmannin, a known inhibitor of actinin-4, led to decrease in NP mRNA levels and also caused nuclear retention of NP, further strengthening our previous observations. Taken together our results indicate that actinin-4, a novel interacting partner of IAV NP, plays a crucial role in viral replication and this interaction may participate in nuclear localization of NP and/or vRNPsThis article is protected by copyright. All rights reserved.Structured digital abstractNP physically interacts with actinin-4 by anti bait coimmunoprecipitation (1,2) NP and actnin-4 colocalize by fluorescence microscopy (View interaction) NP physically interacts with actinin-4 by anti bait coimmunoprecipitation (View interaction) NP binds to actinin-4 by anti tag coimmunoprecipitation (1, 2) NP physically interacts with actinin-4 by anti bait coimmunoprecipitation (View interaction) NP physically interacts with actinin-4 by anti tag coimmunoprecipitation (View interaction) NP physically interacts with actinin-4 by anti bait coimmunoprecipitation (View interaction) NP physically interacts with actinin-4 by anti bait coimmunoprecipitation (View interaction) NP physically interacts with actinin-4 by two hybrid (1,2) NP physically interacts with actinin-4 by anti bait coimmunoprecipitation (View interaction)
    FEBS Journal 05/2014; DOI:10.1111/febs.12828 · 3.99 Impact Factor
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    ABSTRACT: Background: Concerns about influenza vaccine effectiveness in older adults and the role of influenza strains encountered earlier in life led to this study. : Methods: Antibody responses against antigens in the 2011-2012 influenza vaccine at 21 days post-vaccination were analyzed in 264 individuals aged 50-80 years. At Days 0 and 21, sera were tested for hemagglutination-inhibition titers against these vaccine strains and at Day 0 against a panel of 15 historical seasonal strains. Results: The proportions of participants with seroprotective titers ≥1:40 to the vaccine strains at Days 0 and 21, respectively, were 37% and 66% for A(H1N1) and 28% and 63% for A(H3N2). An increasing number of responses ≥1:40 against historical strains was associated with seroprotective responses after vaccination among participants with a titer<1:40 at Day 0 for A(H1N1) and A(H3N2) vaccine strains (P<0.01). In multivariable regression analyses among those with Day 0 titer<1:40, after controlling for age, sex, race, site and diabetes, Day 21 titers ≥ 1:40 for the vaccine A strains were significantly more likely as the number of seroprotective responses against historical strains increased (A(H1N1) odds ratio [OR] 1.41, 95% confidence interval [CI] = 1.09-1.82 and A(H3N2) OR = 1.32, 95% CI = 1.07-1.62). The likelihood of seroconversion was significantly higher with an increasing number of responses to historical strains for A(H3N2) only (OR = 1.24, 95% CI = 1.01-1.52). Seroconversion was significantly less likely as Day 0 vaccine strain titers increased. Conclusions: Seroprotective titers after influenza vaccination increased as the number of responses to historical strains increased.
    03/2014; 10(5). DOI:10.4161/hv.28313
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    Suryaprakash Sambhara, Rino Rappuoli
    Expert Review of Vaccines 01/2014; 11(8). DOI:10.1586/erv.12.79 · 4.22 Impact Factor
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    ABSTRACT: Reports of human infections with highly pathogenic H5N1 avian influenza viruses in many countries in Asia and Africa with varying case fatality rates highlight the pandemic potential of these viruses. In order to contain a rapidly spreading influenza virus in a pandemic scenario, a vaccine which can induce rapid and robust immune responses, preferably in a single dose, is necessary. Murine beta-defensin 2 (Mbd2), a small molecular weight protein expressed by epithelial cells, has been shown to enhance antigen-specific immune responses by recruiting and activating professional antigen presenting cells to the site of vaccination. This study assessed the potential of Mbd2 to enhance the immunogenicity and protective efficacy of a human adenovirus (HAd)-based vaccine expressing the hemagglutinin (HA) and nucleoprotein (NP) [HAd-HA-NP] of an H5N1 influenza virus. A single inoculation of mice with both HAd-HA-NP and a HAd vector expressing Murine β-defensin 2 (HAd-Mbd2) resulted in significantly higher levels of both humoral and cell-mediated immune responses compared to the groups vaccinated only with HAd-HA-NP. These responses were evident even at Day 7 post-immunization. Furthermore, the HAd-HA-NP+HAd-Mbd2-immunized group receiving the lowest vector dose (2×10(7)+1×10(7)) was completely protected against an rgH5N1 virus challenge on Day 7 post-vaccination. These results highlight the potential of Mbd2 as a genetic adjuvant in inducing rapid and robust immune responses to a HAd-based vaccine.
    Virus Research 09/2013; DOI:10.1016/j.virusres.2013.09.013 · 2.83 Impact Factor
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    ABSTRACT: Pathological studies on fatal cases caused by 2009 pandemic influenza H1N1 virus (2009 pH1N1) reported extensive diffuse alveolar damage and virus infection predominantly in the lung parenchyma. However, the host immune response after severe 2009 pH1N1 infection is poorly understood. Herein, we investigated viral load, the immune response, and apoptosis in lung tissues from 50 fatal cases with 2009 pH1N1 virus infection. The results suggested that 7 of the 27 cytokines/chemokines showed remarkably high expression, including IL-1 receptor antagonist protein, IL-6, tumor necrosis factor-α, IL-8, monocyte chemoattractant protein-1, macrophage inflammatory protein 1-β, and interferon-inducible protein-10 in lung tissues of 2009 pH1N1 fatal cases. Viral load, which showed the highest level on day 7 of illness onset and persisted until day 17 of illness, was positively correlated with mRNA levels of IL-1 receptor antagonist protein, monocyte chemoattractant protein-1, macrophage inflammatory protein 1-β, interferon-inducible protein-10, and regulated on activation normal T-cell expressed and secreted. Apoptosis was evident in lung tissues stained by the TUNEL assay. Decreased Fas and elevated FasL mRNA levels were present in lung tissues, and cleaved caspase-3 was frequently seen in pneumocytes, submucosal glands, and lymphoid tissues. The pathogenesis of the 2009 pH1N1 virus infection is associated with viral replication and production of proinflammatory mediators. FasL and caspase-3 are involved in the pathway of 2009 pH1N1 virus-induced apoptosis in lung tissues, and the disequilibrium between the Fas and FasL level in lung tissues could contribute to delayed clearance of the virus and subsequent pathological damages.
    American Journal Of Pathology 08/2013; DOI:10.1016/j.ajpath.2013.06.023 · 4.60 Impact Factor
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    ABSTRACT: The ability to resist infections and respond to vaccinations is greatly reduced in the older adult population owing to a general decline in innate and adaptive immune functions with aging. Over the years several strategies such as increasing the vaccine dose, number of immunizations and using adjuvants have been evaluated to improve the immunogenicity and efficacy of vaccines in the older adult population. Murine ß-defensin 2 (Mbd2) has been shown to function as a molecular adjuvant by recruiting and activating immature dendritic cells (DCs), professional antigen-presenting cells (APC), to the site of the immunization. In this study, we evaluated the potential utility of Mbd2 to enhance the efficacy of an adenoviral vector-based H5N1 influenza vaccine expressing hemagglutinin (HA) and nucleoprotein (NP) (HAd-HA-NP) in an aged mouse model. Our results indicated that immunostimulation with an adenoviral vector expressing Mbd2 (HAd-Mbd2) activated DCs and significantly enhanced the humoral and cellular immune responses induced by HAd-HA-NP. Furthermore, immunostimulation with HAd-Mbd2 followed by immunization with HAd-HA-NP resulted in significantly lower virus titers in the lungs following challenge with a H5N1 influenza virus compared to the group immunized with HAd-HA-NP without immunostimulation. Overall, our results highlight the potential utility of Mbd2 as a molecular adjuvant to enhance the immunogenicity and protective efficacy of vaccines for the elderly.
    Virus Research 07/2013; DOI:10.1016/j.virusres.2013.07.008 · 2.83 Impact Factor
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    ABSTRACT: Recurrent outbreaks of H5, H7 and H9 avian influenza viruses in domestic poultry accompanied by their occasional transmission to humans have highlighted the public health threat posed by these viruses. Newer vaccine approaches for pandemic preparedness against these viruses are needed, given the limitations of vaccines currently approved for H5N1 viruses in terms of their production timelines and the ability to induce protective immune responses in the absence of adjuvants. In this study, we evaluated the feasibility of an adenovirus (AdV)-based multivalent vaccine approach for pandemic preparedness against H5, H7 and H9 avian influenza viruses in a mouse model. Replication-defective AdV vectors expressing hemagglutinin (HA) from different subtypes and nucleoprotein (NP) from one subtype induced high levels of humoral and cellular immune responses and conferred protection against virus replication following challenge with H5, H7 and H9 avian influenza virus subtypes. Inclusion of HA from the 2009 H1N1 pandemic virus in the vaccine formulation further broadened the vaccine coverage. Significantly high levels of HA stalk-specific antibodies were observed following immunization with the multivalent vaccine. Inclusion of NP into the multivalent HA vaccine formulation resulted in the induction of CD8 T cell responses. These results suggest that a multivalent vaccine strategy may provide reasonable protection in the event of a pandemic caused by H5, H7, or H9 avian influenza virus before a strain-matched vaccine can be produced.
    PLoS ONE 04/2013; 8(4):e62496. DOI:10.1371/journal.pone.0062496 · 3.53 Impact Factor
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    ABSTRACT: [This corrects the article on p. e43031 in vol. 7.].
    PLoS ONE 04/2013; 8(4). DOI:10.1371/annotation/14a6b875-ed9d-41ae-8ce6-52e8c5c7f85b · 3.53 Impact Factor
  • J Bradford Bowzard, Priya Ranjan, Suryaprakash Sambhara
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    ABSTRACT: It is currently unclear at which point during viral replication that RNA genomes are first recognized as nonself by the immune system. In this issue of Cell Host & Microbe, Weber et al. show that incoming nucleocapsid-bound genomes are sufficient to bind and activate innate immune sensors.
    Cell host & microbe 03/2013; 13(3):247-9. DOI:10.1016/j.chom.2013.02.012 · 13.02 Impact Factor
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    ABSTRACT: Apoptosis induction is an antiviral host response, however, influenza A virus (IAV) infection promotes host cell death. The nucleoprotein (NP) of IAV is known to contribute to viral pathogenesis, but its role in virus-induced host cell death was hitherto unknown. We observed that NP contributes to IAV infection induced cell death and heterologous expression of NP alone can induce apoptosis in human airway epithelial cells. The apoptotic effect of IAV NP was significant when compared with other known proapoptotic proteins of IAV. The cell death induced by IAV NP was executed through the intrinsic apoptosis pathway. We screened host cellular factors for those that may be targeted by NP for inducing apoptosis and identified human antiapoptotic protein Clusterin (CLU) as a novel interacting partner. The interaction between IAV NP and CLU was highly conserved and mediated through β-chain of the CLU protein. Also CLU was found to interact specifically with IAV NP and not with any other known apoptosis modulatory protein of IAV. CLU prevents induction of the intrinsic apoptosis pathway by binding to Bax and inhibiting its movement into the mitochondria. We found that the expression of IAV NP reduced the association between CLU and Bax in mammalian cells. Further, we observed that CLU overexpression attenuated NP-induced cell death and had a negative effect on IAV replication. Collectively, these findings indicate a new function for IAV NP in inducing host cell death and suggest a role for the host antiapoptotic protein CLU in this process.
    Cell Death & Disease 03/2013; 4:e562. DOI:10.1038/cddis.2013.89 · 5.18 Impact Factor
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    ABSTRACT: Background. Protein energy malnutrition (PEM), a common cause of secondary immune deficiency in children, is associated with an increased risk of infections. Very few studies have addressed the relevance of PEM as a risk factor for influenza.Methods. We investigated the influence of PEM on susceptibility to, and immune responses following, influenza virus infection using isocaloric diets providing either adequate protein (AP; 18%) or very low protein (VLP; 2%) in a mouse model.Results. We found that mice maintained on the VLP diet, when compared to mice fed with the AP diet, exhibited more severe disease following influenza infection based on virus persistence, trafficking of inflammatory cell types to the lung tissue, and virus-induced mortality. Furthermore, groups of mice maintained on the VLP diet showed significantly lower virus-specific antibody response and a reduction in influenza nuclear protein-specific CD8(+) T cells compared with mice fed on the AP diet. Importantly, switching diets for the group maintained on the VLP diet to the AP diet improved virus clearance, as well as protective immunity to viral challenge.Conclusions. Our results highlight the impact of protein energy on immunity to influenza infection and suggest that balanced protein energy replenishment may be one strategy to boost immunity against influenza viral infections.
    The Journal of Infectious Diseases 09/2012; DOI:10.1093/infdis/jis527 · 5.85 Impact Factor
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    ABSTRACT: Retinoic acid inducible gene I (RIG-I)-like receptors (RLRs) function as cytoplasmic sensors for viral RNA to initiate antiviral responses including type I interferon (IFN) production. It has been unclear how RIG-I encounters and senses viral RNA. To address this issue, we examined intracellular localization of RIG-I in response to viral infection using newly generated anti-RIG-I antibody. Immunohistochemical analysis revealed that RLRs localized in virus-induced granules containing stress granule (SG) markers together with viral RNA and antiviral proteins. Because of similarity in morphology and components, we termed these aggregates antiviral stress granules (avSGs). Influenza A virus (IAV) deficient in non-structural protein 1 (NS1) efficiently generated avSGs as well as IFN, however IAV encoding NS1 produced little. Inhibition of avSGs formation by removal of either the SG component or double-stranded RNA (dsRNA)-dependent protein kinase (PKR) resulted in diminished IFN production and concomitant enhancement of viral replication. Furthermore, we observed that transfection of dsRNA resulted in IFN production in an avSGs-dependent manner. These results strongly suggest that the avSG is the locus for non-self RNA sensing and the orchestration of multiple proteins is critical in the triggering of antiviral responses.
    PLoS ONE 08/2012; 7(8):e43031. DOI:10.1371/journal.pone.0043031 · 3.53 Impact Factor
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    Jin Hyang Kim, William G Davis, Suryaprakash Sambhara, Joshy Jacob
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    ABSTRACT: Original antigenic sin is a phenomenon wherein sequential exposure to closely related influenza virus variants reduces antibody (Ab) response to novel antigenic determinants in the second strain and, consequently, impairs the development of immune memory. This could pose a risk to the development of immune memory in persons previously infected with or vaccinated against influenza. Here, we explored strategies to overcome original antigenic sin responses in mice sequentially exposed to two closely related hemagglutinin 1 neuraminidase 1 (H1N1) influenza strains A/PR/8/34 and A/FM/1/47. We found that dendritic cell-activating adjuvants [Bordetella pertussis toxin (PT) or CpG ODN or a squalene-based oil-in-water nanoemulsion (NE)], upon administration during the second viral exposure, completely protected mice from a lethal challenge and enhanced neutralizing-Ab titers against the second virus. Interestingly, PT and NE adjuvants when administered during the first immunization even prevented original antigenic sin in subsequent immunization without any adjuvants. As an alternative to using adjuvants, we also found that repeated immunization with the second viral strain relieved the effects of original antigenic sin. Taken together, our studies provide at least three ways of overcoming original antigenic sin.
    Proceedings of the National Academy of Sciences 08/2012; 109(34):13751-6. DOI:10.1073/pnas.0912458109 · 9.81 Impact Factor
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    ABSTRACT: Myeloid dendritic cells (mDCs) have long been thought to function as classical APCs for T cell responses. However, we demonstrate that influenza viruses induce rapid differentiation of human monocytes into mDCs. Unlike the classic mDCs, the virus-induced mDCs failed to upregulate DC maturation markers and were unable to induce allogeneic lymphoproliferation. Virus-induced mDCs secreted little, if any, proinflammatory cytokines; however, they secreted a substantial amount of chemoattractants for monocytes (MCP-1 and IP-10). Interestingly, the differentiated mDCs secreted type I IFN and upregulated the expression of IFN-stimulated genes (tetherin, IFITM3, and viperin), as well as cytosolic viral RNA sensors (RIG-I and MDA5). Additionally, culture supernatants from virus-induced mDCs suppressed the replication of virus in vitro. Furthermore, depletion of monocytes in a mouse model of influenza infection caused significant reduction of lung mDC numbers, as well as type I IFN production in the lung. Consequently, increased lung virus titer and higher mortality were observed. Taken together, our results demonstrate that the host responds to influenza virus infection by initiating rapid differentiation of circulating monocytes into IFN-producing mDCs, which contribute to innate antiviral immune responses.
    The Journal of Immunology 08/2012; 189(5):2257-65. DOI:10.4049/jimmunol.1200168 · 5.36 Impact Factor
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    ABSTRACT: Recognition of pathogen-associated molecular patterns by pattern recognition receptors of the innate immune system is crucial for the initiation of innate and adaptive responses and for immunological memory. We investigated the role of TLR7 in the induction of adaptive immunity and long-term memory following influenza virus infection and vaccination in C57BL/6 mice. During infection with influenza A/PR8/34 virus, the absence of either TLR7 or MyD88 leads to reduced virus-specific antibodies in the serum and antibody-secreting cells in their secondary lymphoid organs, particularly in bone marrow. In spite of this, the absence of TLR7/MyD88 signaling did not impair the production of protective antibodies. Following immunization with the 2009 pandemic inactivated split vaccine, TLR7(-/-) mice had significantly lower levels of germinal center formation, antibody-secreting cells, and circulating influenza virus-specific antibodies than control animals. Consequently, TLR7(-/-) mice failed to develop protective immunological memory upon challenge. Furthermore, the immunogenicity of the split vaccine was likely due to TLR7 recognition of virion RNA, as its removal from the split vaccine significantly reduced the levels of influenza virus-specific antibodies and compromised the vaccine protective efficacy in mice. Taken together, our data demonstrate that TLR7 plays an important role in vaccine-induced humoral immune responses to influenza virus through the interaction with viral RNA present in the split vaccine.
    Journal of Virology 07/2012; 86(20):10988-98. DOI:10.1128/JVI.01064-12 · 4.65 Impact Factor
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    ABSTRACT: Retinoic acid inducible gene-I (RIG-I) is a key regulator of antiviral immunity. RIG-I is generally thought to be activated by ssRNA species containing a 5'-triphosphate (PPP) group or by unphosphorylated dsRNA up to ~300 bp in length. However, it is not yet clear how changes in the length, nucleotide sequence, secondary structure, and 5' end modification affect the abilities of these ligands to bind and activate RIG-I. To further investigate these parameters in the context of naturally occurring ligands, we examined RNA sequences derived from the 5' and 3' untranslated regions (UTR) of the influenza virus NS1 gene segment. As expected, RIG-I-dependent interferon-β (IFN-β) induction by sequences from the 5' UTR of the influenza cRNA or its complement (26 nt in length) required the presence of a 5'PPP group. In contrast, activation of RIG-I by the 3' UTR cRNA sequence or its complement (172 nt) exhibited only a partial 5'PPP-dependence, as capping the 5' end or treatment with CIP showed a modest reduction in RIG-I activation. Furthermore, induction of IFN-β by a smaller, U/A-rich region within the 3' UTR was completely 5'PPP-independent. Our findings demonstrated that RNA sequence, length, and secondary structure all contributed to whether or not the 5'PPP moiety is needed for interferon induction by RIG-I.
    PLoS ONE 03/2012; 7(3):e32661. DOI:10.1371/journal.pone.0032661 · 3.53 Impact Factor
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    ABSTRACT: The prevalence of preexisting immunity to adenoviruses in the majority of the human population might adversely impact the development of adaptive immune responses against adenovirus vector-based vaccines. To address this issue, we primed BALB/c mice either intranasally (i.n.) or intramuscularly (i.m.) with varying doses of wild type (WT) human adenovirus subtype 5 (HAd5). Following the development of immunity against HAd5, we immunized animals via the i.n. or i.m. route of inoculation with a HAd vector (HAd-HA-NP) expressing the hemagglutinin (HA) and nucleoprotein (NP) of A/Vietnam/1203/04 (H5N1) influenza virus. The immunogenicity and protection results suggest that low levels of vector immunity (<520 virus-neutralization titer) induced by priming mice with up to 10(7) plaque forming units (p.f.u.) of HAd-WT did not adversely impact the protective efficacy of the vaccine. Furthermore, high levels of vector immunity (approximately 1500 virus-neutralization titer) induced by priming mice with 10(8) p.f.u. of HAd-WT were overcome by either increasing the vaccine dose or using alternate routes of vaccination. A further increase in the priming dose to 10(9) p.f.u. allowed only partial protection. These results suggest possible strategies to overcome the variable levels of human immunity against adenoviruses, leading to better utilization of HAd vector-based vaccines.
    PLoS ONE 03/2012; 7(3):e33428. DOI:10.1371/journal.pone.0033428 · 3.53 Impact Factor
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    ABSTRACT: The influenza virus neuraminidase (NA) protein primarily aids in the release of progeny virions from infected cells. Here, we demonstrate a novel role for NA in enhancing host cell survival by activating the Src/Akt signaling axis via an interaction with carcinoembryonic antigen-related cell adhesion molecule 6/cluster of differentiation 66c (C6). NA/C6 interaction leads to increased tyrosyl phosphorylation of Src, FAK, Akt, GSK3β, and Bcl-2, which affects cell survival, proliferation, migration, differentiation, and apoptosis. siRNA-mediated suppression of C6 resulted in a down-regulation of activated Src, FAK, and Akt, increased apoptosis, and reduced expression of viral proteins and viral titers in influenza virus-infected human lung adenocarcinoma epithelial and normal human bronchial epithelial cells. These findings indicate that influenza NA not only aids in the release of progeny virions, but also cell survival during viral replication.
    Journal of Biological Chemistry 03/2012; 287(18):15109-17. DOI:10.1074/jbc.M111.328070 · 4.60 Impact Factor

Publication Stats

2k Citations
450.65 Total Impact Points


  • 2014
    • University of Washington Seattle
      • Department of Immunology
      Seattle, Washington, United States
  • 2002–2014
    • Centers for Disease Control and Prevention
      • Influenza Division
      Атланта, Michigan, United States
    • U.S. Food and Drug Administration
      Washington, Washington, D.C., United States
  • 2008–2013
    • Purdue University
      • Department of Comparative Pathobiology (CPB)
      ウェストラファイエット, Indiana, United States
  • 2012
    • International Centre for Genetic Engineering and Biotechnology
      Trst, Friuli Venezia Giulia, Italy
    • Kyoto University
      • Institute for Virus Research
      Kyoto, Kyoto-fu, Japan
    • Emory University
      Atlanta, Georgia, United States
  • 2011
    • University of Georgia
      Атина, Georgia, United States
  • 2007
    • National Institute of Allergy and Infectious Diseases
      Maryland, United States