Marylyn M. Addo

Genetic Characterization of Human Immunodeficiency Virus Type 1 in Elite Controllers: Lack of Gross Genetic Defects or Common Amino Acid Changes

ABSTRACT Despite reports of viral genetic defects in persons who control human immunodeficiency virus type 1 (HIV-1) in the absence of antiviral therapy, the extent to which such defects contribute to the long-term containment of viremia is not known. Most previous studies examining for such defects have involved small numbers of subjects, primarily focused on subjects expressing HLA-B57, or have examined single viral genes, and they have focused on cellular proviral DNA rather than plasma viral RNA sequences. Here, we attempted viral sequencing from 95 HIV-1 elite controllers (EC) who maintained plasma viral loads of <50 RNA copies/ml in the absence of therapy, the majority of whom did not express HLA-B57. HIV-1 gene fragments were obtained from 94% (89/95) of the EC, and plasma viral sequences were obtained from 78% (61/78), the latter indicating the presence of replicating virus in the majority of EC. Of 63 persons for whom nef was sequenced, only three cases of nef deletions were identified, and gross genetic defects were rarely observed in other HIV-1 coding genes. In a codon-by-codon comparison between EC and persons with progressive infection, correcting for HLA bias and coevolving secondary mutations, a significant difference was observed at only three codons in Gag, all three of which represented the historic population consensus amino acid at the time of infection. These results indicate that the spontaneous control of HIV replication is not attributable to shared viral genetic defects or shared viral polymorphisms.

HIV-1 specific CD8+ T cells with an effector phenotype and control of viral replication

Most people infected with HIV-1 cannot control viral replication despite the presence of virus-specific CD8+ T cells. It has been postulated that this inability is related to the failure of these cells to mature into fully differentiated effector cells. We tested this hypothesis by comparing the maturation phenotype of virus-specific CD8+ T cells in people who could control viral replication off anti-retroviral therapy with those who could not. In five patients with treated acute HIV-1-infection, structured treatment interruption (STI) induced control of viral replication was associated with expansion of virus-specific CD8+ T cells with a fully differentiated effector phenotype. These effector cells were also expanded in treatment-naive chronically infected individuals who spontaneously controlled viral replication, and augmented expression of perforin was noted in both settings. Our data show that full maturation of virus-specific CD8+ T cells is possible in the context of HIV-1-infection, and suggest that such maturation might be important in viral control.

HIV-1 Antiviral Activity of Recombinant Natural Killer Cell Enhancing Factors, NKEF-A and NKEF-B, Members of the Peroxiredoxin Family*

CD8+ T-cells are a major source for the production of non-cytolytic factors that inhibit HIV-1 replication. In order to characterize further these factors, we analyzed gene expression profiles of activated CD8+ T-cells using a human cDNA expression array containing 588 human cDNAs. mRNA for the chemokine I-309 (CCL1), the cytokines granulocyte-macrophage colony-stimulating factor and interleukin-13, and natural killer cell enhancing factors (NKEF) -A and -B were up-regulated in bulk CD8+ T-cells from HIV-1 seropositive individuals compared with seronegative individuals. Recombinant NKEF-A and NKEF-B inhibited HIV-1 replication when exogenously added to acutely infected T-cells at an ID50 (dose inhibiting HIV-1 replication by 50%) of ∼130 nm (3 μg/ml). Additionally, inhibition against dual-tropic simian immunodeficiency virus and dual-tropic simian-human immunodeficiency virus was found. T-cells transfected with NKEF-A or NKEF-B cDNA were able to inhibit 80–98% HIV-1 replication in vitro. Elevated plasma levels of both NKEF-A and NKEF-B proteins were detected in 23% of HIV-infected non-treated individuals but not in persons treated with highly active antiviral therapy or uninfected persons. These results indicate that the peroxiredoxin family members NKEF-A and NKEF-B are up-regulated in activated CD8+ T-cells in HIV infection, and suggest that these antioxidant proteins contribute to the antiviral activity of CD8+ T-cells.

Differential Immunogenicity of HIV‐1 Clade C Proteins in Eliciting CD8+ and CD4+ Cell Responses

BACKGROUND The relative immunogenicity of human immunodeficiency virus type 1 (HIV-1) proteins for CD8+ and CD4+ cell responses has not been defined. METHODS HIV-1-specific T cell responses were evaluated in 65 chronically HIV-1-infected untreated subjects by interferon- gamma flow cytometry with peptides spanning the clade C consensus sequence. RESULTS The magnitude of HIV-1-specific CD8+ T cell responses correlated significantly with CD4+ cell responses, but the percentage of CD8+ T cells directed against HIV-1 (median, 2.76%) was always greater than that of CD4+ cells (median, 0.24%). Although CD8+ T cell responses were equally distributed among Gag, Pol, and the regulatory and accessory proteins, Gag was the dominant target for CD4+ cell responses. There was no consistent relationship between virus-specific CD8+ or CD4+ cell response and viral load. However, the median viral load in subjects in whom Gag was the dominant CD8+ T cell target was significantly lower than that in subjects in whom non-Gag proteins were the main target (P=.007). CONCLUSIONS Gag-specific responses dominate the CD4+ T cell response to HIV, whereas CD8+ T cell responses are broadly distributed, which indicates differential immunogenicity of these cells against HIV-1. The preferential targeting of Gag by CD8+ T cells is associated with enhanced control of viral load.

Transmission of oral Candida albicans strains between HIV-positive patients

numbers of HIV infections identified as Thai-B and subtype C increased to 11 and 9, respectively. Within each subtype, nucleotide differences of 3-6% for subtype B and 2-6% for subtype C viruses were observed. Although they clustered closely within each subtype, no two viral sequences were identical, ruling out laboratory contamination or sample misidentification. The low nucleotide divergence supports the recent introduction of the two subtypes into the area. Subtype B is one of the two major strains recognised in Thailand. 3 The finding of Thai-B-like strains among intravenous drug users along the border area of Yunnan suggests that Thai-B viruses may be present in several countries in the region including China, Myanmar, and Thailand. Subtype C, on the other hand, has been reported from South Africa and India and lately from Brazil.4&deg;5 It is interesting that subtype C viruses have not yet been found in Thailand, since it is close to China and India. If subtype C is present in Thailand, it may constitute only a very small proportion of HIV infections and may not easily be detected. Further characterisation of epidemiologically representative samples from Yunnan will be necessary to elucidate the complex interactions of viral subtypes, transmission mode, geographic distribution of strains, and timing of the epidemic. Our collaborating colleagues were Dr Xiaoliang Liu, Dr Jun Chen, Dr Daqin Li, Dr Shuquan Qu, and Dr Guiyun Zhang, Institute of Epidemiology and Microbiology, Chinese Academy of Preventive Medicine; and Dr J Richard George, Dr Gerald Schochetman, and Dr Marcia L Kalish, Division of HIV/AIDS, CDC.

Systems Vaccinology Identifies an Early Innate Immune Signature as a Correlate of Antibody Responses to the Ebola Vaccine rVSV-ZEBOV

Summary Predicting vaccine efficacy remains a challenge. We used a systems vaccinology approach to identify early innate immune correlates of antibody induction in humans receiving the Ebola vaccine rVSV-ZEBOV. Blood samples from days 0, 1, 3, 7, and 14 were analyzed for changes in cytokine levels, innate immune cell subsets, and gene expression. Integrative statistical analyses with cross-validation identified a signature of 5 early innate markers correlating with antibody titers on day 28 and beyond. Among those, IP-10 on day 3 and MFI of CXCR6 on NK cells on day 1 were independent correlates. Consistently, we found an early gene expression signature linked to IP-10. This comprehensive characterization of early innate immune responses to the rVSV-ZEBOV vaccine in humans revealed immune signatures linked to IP-10. These results suggest correlates of vaccine-induced antibody induction and provide a rationale to explore strategies for augmenting the effectiveness of vaccines through manipulation of IP-10.

Viren überlisten: Globale Virusinfektionen werden beherrschbar – aber neue Gefahren drohen

Zusammenfassung Infektionen begleiten und beschäftigen die Menschheit seit vielen Jahrhunderten. Derzeit zählen allein fünf von den zehn häufigsten Todesursachen weltweit zu den Infektionskrankheiten. Oft ausbruchsartig haben besonders Viruserkrankungen seit dem Beginn aufgezeichneter Historie viele Todesopfer gefordert, so zum Beispiel die „Spanische Grippe“ 1918 (Influenzavirus), AIDS (Human Immunodeficiency Virus) und erst vor Kurzem in bisher nie gesehenem Ausmaß das Ebolavirus. Warum besonders virale Erreger für die Wissenschaft ein große Herausforderung darstellen und wie virale Erreger das menschliche Immunsystem überlisten, zeigen die folgenden Überlegungen. Das Kapitel beschreibt darüber hinaus an konkreten Beispielen erfolgreiche Gegenmaßnahmen im Kampf gegen Viren.