Frank Msafiri, Agricola Joachim, Said Aboud, Eligius Lyamuya, Patricia Munseri, Britta Wahren, Eric Sandström, Mangala Rao, Charlotta Nilsson, Gunnel Biberfeld

Affiliates

Frank Msafiri[1, 2], Agricola Joachim[1], Said Aboud[1], Eligius Lyamuya[1], Patricia Munseri [3], Britta Wahren[4], Eric Sandström[5], Mangala Rao[6], Charlotta Nilsson[2, 7], Gunnel Biberfeld[8] Muhimbili University of Health and Allied Sciences, Department of Microbiology and Immunology, Dar es Salaam, Tanzania [1] Karolinska Institutet, Department of Laboratory Medicine, Stockholm, Sweden[2] Muhimbili University of Health and Allied Sciences, Department of Internal Medicine, Dar es Salaam, Tanzania [3] Karolinska Institutet, Department of Microbiology, Tumor and Cell Biology, Stockholm, Sweden[4] Karolinska Institutet at Södersjukhuset, Venhälsan, Stockholm, Sweden[5] United States Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA[6] Public Health Agency of Sweden, Department of Microbiology, Solna, Sweden[7] Karolinska Institutet, Department of Public Health Sciences, Stockholm, Sweden[8]

Abstract

Background
Antibodies that target variable regions 1 and 2 (V1/V2) of human immunodeficiency virus -1 (HIV-1) envelope were reported to correlate with reduced risk of infection in the RV144 HIV vaccine efficacy trial. We examined; 1) the capability of a HIV-DNA prime HIV-modified vaccinia virus Ankara (MVA) boost vaccine strategy to elicit antibody responses to the VIV2 domain of the envelope protein and 2) the three-year durability of the induced anti-V1V2 responses.

Method
Healthy Tanzanian vaccinees received three HIV-1 DNA immunizations delivered intradermally using a needle-free device (Bioject) at weeks 0, 4, and 12 and three HIV-MVA immunizations delivered intramuscularly using needle and syringe at months 9, 21 and 57 in the HIVIS03/06 phase II vaccine trial. Plasma samples collected four weeks after the second HIV-MVA boost, three years after the second HIV-MVA immunization, and four weeks after the third HIV-MVA boost were analyzed. IgG antibodies to CRF01_AE (A244), subtype C (CN54) and subtype B (Case A2) scaffolded gp70V1V2 proteins were measured using enzyme-linked immunosorbent assay (ELISA) and to cyclic V2 peptides of A244 and Consensus C using surface plasmon resonance (SPR) assay. Anti-V1V2 IgG subclasses (IgG1-IgG4) to A244 scaffolded gp70V1V2 protein were tested using ELISA.

Results
Four weeks after the second HIV-MVA immunization, IgG responses to the V1V2 regions of A244, CN54, and Case A2, were detected in 19/19 (100%), 9/19 (47%) and 3/19 (16%) of the tested vaccinees respectively. Three years later, at the time of the third HIV-MVA boost, antibody responses to A244 and CN54 were still detectable, but not to Case A2 antigen. Anti-V1V2 A244 IgG responses were present in 15/20 (75%) of vaccine recipients and anti-V1V2 CN54 IgG responses in 2/20 (10%) of vaccinees. IgG1 was the most predominant subclass. Anti-V1V2 A244 IgG1 responses were frequently found four weeks after the second HIV-MVA immunization 17/20 (85%), and declined to 5/20 (25%) after three years. The V1V2 IgG1 response rates to A244 were greatly improved by the third HIV-MVA immunization, increasing to 13/20 (65%), P=0.002. The frequency of IgG3 antibody response to gp70V1V2 proteins of A244 was 3/20 (15%) four weeks post second HIV-MVA vaccination, and undetectable three years later, at the time of the third HIV-MVA boost. Anti-V1V2 A244 IgG3 responses were not substantially increased by the third HIV-MVA immunization. Anti-V1V2 IgG4 antibody responses to A244 were rare, induced in 1/20 (5%) vaccinee only and no anti-V1V2 A244 IgG2 antibody responses were detected.
Four weeks after the second HIV-MVA immunization, the anti-V1V2 IgG antibody titer to A244 was a median of 3200 (interquartile range, (IQR), 1600-12800). The antibody levels fell to a median of 300 (IQR, 50-800) after three years, but increased significantly to a median of 1600 (IQR, 800-3200), after the third HIV-MVA immunization, P<0.0001. The titers of anti-V1V2 CN54 and anti-V1V2 Case A2 IgG responses were low.
SPR/Biacore analysis data supported the ELISA findings.

Conclusion
The HIV-DNA prime HIV-MVA boosting vaccination strategy induced durable VIV2 antibody responses to CRF01_AE in a high proportion of vaccinees.