Characterization of HIV-1 gp120 antibody specificities induced in anogenital secretions of RV144 vaccine recipients after late boost immunizations.

Sexual transmission is the principal driver of the human immunodeficiency virus (HIV) pandemic. Understanding HIV vaccine-induced immune responses at mucosal surfaces can generate hypotheses regarding mechanisms of protection, and may influence vaccine development. The RV144 (ClinicalTrials.gov NCT00223080) efficacy trial showed protection against HIV infections but mucosal samples were not collected, therefore, the contribution of mucosal antibodies to preventing HIV-1 acquisition is unknown. Here, we report the generation, magnitude and persistence of antibody responses to recombinant gp120 envelope and antigens including variable one and two loop scaffold antigens (gp70V1V2) previously shown to correlate with risk in RV144. We evaluated antibody responses to gp120 A244gD and gp70V1V2 92TH023 (both CRF01_AE) and Case A2 (subtype B) in cervico-vaginal mucus (CVM), seminal plasma (SP) and rectal secretions (RS) from HIV-uninfected RV144 vaccine recipients, who were randomized to receive two late boosts of ALVAC-HIV/AIDSVAX®B/E, AIDSVAX®B/E, or ALVAC-HIV alone at 0 and 6 months. Late vaccine boosting increased IgG geometric mean titers (GMT) to gp120 A244gD in AIDSVAX®B/E and ALVAC-HIV/AIDSVAX®B/E CVM (28 and 17 fold, respectively), followed by SP and RS. IgG to gp70V1V2 92TH023 increased in AIDSVAX®B/E and ALVAC-HIV/AIDSVAX®B/E CVM (11-17 fold) and SP (2 fold) two weeks post first boost. IgG to Case A2 was only detected in AIDSVAX®B/E and ALVAC-HIV/AIDSVAX®B/E CVM. Mucosal IgG to gp120 A244gD (CVM, SP, RS), gp70V1V2 92TH023 (CVM, SP), and Case A2 (CVM) correlated with plasma IgG levels (p<0.001). Although the magnitude of IgG responses declined after boosting, anti-gp120 A244gD IgG responses in CVM persisted for 12 months post final vaccination. Further studies in localization, persistence and magnitude of envelope specific antibodies (IgG and dimeric IgA) in anogenital secretions will help determine their role in preventing mucosal HIV acquisition.

Comparison of Antibody Responses Induced by RV144, VAX003, and VAX004 Vaccination Regimens.

The RV144 prime-boost regimen demonstrated efficacy against HIV acquisition while VAX003 and VAX004 did not. Although these trials differed by risk groups, immunization regimens, and immunogens, antibody responses may have contributed to the differences observed in vaccine efficacy. We assessed HIV-specific IgG, both total and subclass, and IgA binding to HIV envelope (Env): gp120 proteins and Cyclic V2 (CycV2) and CycV3 peptides and gp70 V1 V2 scaffolds in these 3 HIV vaccine trials. After two protein immunizations, IgG responses to 92TH023 gp120 (contained in ALVAC-HIV vaccine) were significantly higher in RV144 but responses to other Env were higher in the VAX trials lacking ALVAC-HIV. IgG responses declined significantly between vaccinations. All trials induced antibodies to gp70 V1 V2 but VAX004 responses to 92TH023 gp70 V1 V2 were weak. All CycV2 responses were undetectable in VAX004 while 92TH023 gp70 V1 V2 was detected in both RV144 and VAX003 but MN CycV2 was detected only in VAX003. Multiple protein vaccinations in VAX trials did not improve magnitude or durability of V1 V2 and CycV2 antibodies. Herpes simplex virus glycoprotein D (gD) peptide at the N terminus of AIDSVAX® B/E and B/B gp120 proteins induced antibodies in all trials, although significantly higher in VAX trials. gD peptide induced IgA, IgG1, IgG2, and IgG3 but not IgG4. Multiple protein vaccinations decreased IgG3 and increased IgG4 changing subclass contribution to total IgG. Although confounded by different modes of HIV transmission, higher Env-specific IgA and IgG4 binding antibodies induced in the VAX trials compared to RV144 raises the hypothesis that these differences may have contributed to different vaccine efficacy results.

IgG Antibody Responses to Recombinant gp120 Proteins, gp70V1/V2 Scaffolds, and a CyclicV2 Peptide in Thai Phase I/II Vaccine Trials Using Different Vaccine Regimens.

RV144 correlates of risk analysis showed that IgG antibodies to gp70V1V2 scaffolds inversely correlated with risk of HIV acquisition. We investigated IgG antibody responses in RV135 and RV132, two ALVAC-HIV prime-boost vaccine trials conducted in Thailand prior to RV144. Both trials used ALVAC-HIV (vCP1521) at 0, 1, 3, and 6 months and HIV-1 gp120MNgD and gp120A244gD in alum (RV135) or gp120SF2 and gp120CM235 in MF59 (RV132) at 3 and 6 months. We assessed ELISA binding antibodies to the envelope proteins (Env) 92TH023, A244gD and MNgD, cyclicV2, and gp70V1V2 CaseA2 (subtype B) and 92TH023 (subtype CRF01_AE), and Env-specific IgG1 and IgG3. Antibody responses to gp120 A244gD, MNgD, and gp70V1V2 92TH023 scaffold were significantly higher in RV135 than in RV132. Antibodies to gp70V1V2 CaseA2 were detected only in RV135 vaccine recipients and IgG1 and IgG3 antibody responses to A244gD were significantly higher in RV135. IgG binding to gp70V1V2 CaseA2 and CRF01_AE scaffolds was higher with the AIDSVAX(®)B/E boost but both trials showed similar rates of antibody decline post-vaccination. MF59 did not result in higher IgG antibody responses compared to alum with the antigens tested. However, notable differences in the structure of the recombinant proteins and dosage used for immunizations may have contributed to the magnitude and specificity of IgG induced by the two trials.

Hepatitis C genotype distribution and homology among geographically disparate injecting drug users in Afghanistan.

Hepatitis C virus (HCV) prevalence is high among injecting drug users in Afghanistan, but transmission dynamics are poorly understood. Samples from HCV-infected injecting drug users were sequenced to determine circulating genotypes and potential transmission linkages. Serum samples were obtained from injecting drug user participants in Hirat, Jalalabad, and Mazar-i-Sharif between 2006 and 2008 with reactive anti-HCV rapid tests. Specimens with detected HCV viremia were amplified and underwent sequence analysis. Of 113 samples evaluated, 25 samples (35.2%) were only typeable in NS5B, nine samples (12.7%) were only typeable in CE1, and 37 samples (52.1%) were genotyped in both regions. Of those with typeable HCV, all were Afghan males with a mean age of 31.1 (standard deviation [SD] ± 8.0) years and mean duration of injecting of 3.9 (SD ± 4.3) years. Most reported residence outside Afghanistan in the last decade (90.1%) and prior incarceration (76.8%). HCV genotypes detected were: 1a, (35.2%, n = 25), 3a (62.0%, n = 44), and 1b (2.8%, n = 2). Cluster formation was detected in NS5B and CE1 and were generally from within the same city. All participants within clusters reported being a refugee in Iran compared to 93.5% of those outside clusters. Only 22.2% (4/11) of those within clusters had been refugees in Pakistan and these four individuals had also been refugees in Iran. Predominance of genotype 3a and the association between HCV viremia and having been a refugee in Iran potentially reflects migration between Afghanistan and Iran among IDUs from Mazar-i-Sharif and Hirat and carry implications for harm reduction programs for this migratory population.

Two unique recombinant forms identified in incident HIV type 1 infections in Thai blood donors.

HIV-1 genetic diversity of recently seroconverting (<12 months) Thai repeated blood donors attending the National Blood Centre, Thai Red Cross Society (NBC, TRCS) from September 2007 until March 2008 was assessed. Ten HIV-1 recent seroconvertors (10/239,134 donations) were identified during the study period. The estimated median time to seroconversion was 67.3 days (range: 45.5-102.0 days), and viral load ranged from 307 to 341,805 copies HIV-1 RNA/ml. MHAbce, a real-time-based PCR genotyping assay, identified six CRF01_AE, two CRF01_AE/B recombinants, one subtype B, and one CRF01_AE/B dual infection. Nine samples were further characterized by full genome sequencing, identifying CRF01_AE (N=6), unique CRF01_AE/B recombinants (N=2), and subtype B (N=1). One recombinant contained 13 breakpoints located in gag, pol, vif, vpr, env, and nef while the other recombinant contained 10 breakpoints located in pol, vif, env, and nef. This study found two unique CRF01B recombinants circulating in 10 recent HIV-1-positive subjects from a blood donor population in Thailand.