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. 2015 Aug 12;11(8):e1005101.
doi: 10.1371/journal.ppat.1005101. eCollection 2015 Aug.

Mucosal B Cells Are Associated with Delayed SIV Acquisition in Vaccinated Female but Not Male Rhesus Macaques Following SIVmac251 Rectal Challenge

Iskra Tuero  1 , Venkatramanan Mohanram  1 , Thomas Musich  1 , Leia Miller  1 , Diego A Vargas-Inchaustegui  1 , Thorsten Demberg  1 , David Venzon  2 , Irene Kalisz  3 , V S Kalyanaraman  3 , Ranajit Pal  3 , Maria Grazia Ferrari  3 , Celia LaBranche  4 , David C Montefiori  4 , Mangala Rao  5 , Monica Vaccari  6 , Genoveffa Franchini  6 , Susan W Barnett  7 , Marjorie Robert-Guroff  1
Affiliations

Mucosal B Cells Are Associated with Delayed SIV Acquisition in Vaccinated Female but Not Male Rhesus Macaques Following SIVmac251 Rectal Challenge

Iskra Tuero et al. PLoS Pathog. .

Abstract

Many viral infections, including HIV, exhibit sex-based pathogenic differences. However, few studies have examined vaccine-related sex differences. We compared immunogenicity and protective efficacy of monomeric SIV gp120 with oligomeric SIV gp140 in a pre-clinical rhesus macaque study and explored a subsequent sex bias in vaccine outcome. Each immunization group (16 females, 8 males) was primed twice mucosally with replication-competent Ad-recombinants encoding SIVsmH4env/rev, SIV239gag and SIV239nefΔ1-13 and boosted twice intramuscularly with SIVmac239 monomeric gp120 or oligomeric gp140 in MF59 adjuvant. Controls (7 females, 5 males) received empty Ad and MF59. Up to 9 weekly intrarectal challenges with low-dose SIVmac251 were administered until macaques became infected. We assessed vaccine-induced binding, neutralizing, and non-neutralizing antibodies, Env-specific memory B cells and plasmablasts/plasma cells (PB/PC) in bone marrow and rectal tissue, mucosal Env-specific antibodies, and Env-specific T-cells. Post-challenge, only one macaque (gp140-immunized) remained uninfected. However, SIV acquisition was significantly delayed in vaccinated females but not males, correlated with Env-specific IgA in rectal secretions, rectal Env-specific memory B cells, and PC in rectal tissue. These results extend previous correlations of mucosal antibodies and memory B cells with protective efficacy. The gp140 regimen was more immunogenic, stimulating elevated gp140 and cyclic V2 binding antibodies, ADCC and ADCP activities, bone marrow Env-specific PB/PC, and rectal gp140-specific IgG. However, immunization with gp120, the form of envelope immunogen used in RV144, the only vaccine trial to show some efficacy, provided more significant acquisition delay. Further over 40 weeks of follow-up, no gp120 immunized macaques met euthanasia criteria in contrast to 7 gp140-immunized and 2 control animals. Although males had higher binding antibodies than females, ADCC and ADCP activities were similar. The complex challenge outcomes may reflect differences in IgG subtypes, Fc glycosylation, Fc-R polymorphisms, and/or the microbiome, key areas for future studies. This first demonstration of a sex-difference in SIV vaccine-induced protection emphasizes the need for sex-balancing in vaccine trials. Our results highlight the importance of mucosal immunity and memory B cells at the SIV exposure site for protection.

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Conflict of interest statement

IK, RP and MGF are current employees and VSK is a past employee of Advanced BioScience Laboratories, Inc. SWB was an employee and shareholder of Novartis Vaccines when this work was conducted. She is currently an employee and shareholder of Glaxo Smith Kline, Cambridge, MA, USA. This does not alter our adherence to all PLOS Pathogens policies on sharing data and materials.

Figures

Fig 1
Fig 1. Immunization scheme and delayed acquisition after intrarectal repetitive SIVmac251 low dose challenges.
(A) Immunization and challenge schedule. O = oral; IN = intranasal; IT = intratracheal; IM = intramuscular; IR = intrarectal. Dosages and further details are provided in on-line Methods. (B) No difference in SIV acquisition between all immunized macaques and current controls (n = 12). (C) No difference in SIV acquisition rate in gp120- and gp140-immunized macaques and current controls. (D) Similar acquisition rate in historical (n = 53) and current controls. (E) Delayed SIV acquisition in all immunized macaques compared to combined controls (n = 65). (F) Delayed SIV acquisition in all immunized females (n = 32) compared to combined control females (n = 24) but not (G) in all immunized males (n = 16) compared to combined control males (n = 41). (H) Delayed SIV acquisition in gp120-immunized females compared to combined control females. (I) Trend for delayed SIV acquisition in gp140-immunized females compared to combined control females. No difference in SIV acquisition rate in gp120-immunized males (J) and gp140-immunized males (K) compared to combined control males.
Fig 2
Fig 2. Comparison of immune responses between female and male macaques.
Binding antibody titers to SIVmac239 gp120 and gp140 over the course of immunization and following infection in (A) gp120- and (B) gp140-immunized female and male macaques. (C) Binding antibody titers by sex of combined gp120- and gp140 immunization groups to SIVmac239 gp120 over the course of immunization and 2wkpi. (D) Binding antibody titers to SIVE660 gp120 over the course of immunization in females and males of combined gp120- and gp140-immunization groups. Pre-bleed samples were not tested but binding titers of control macaque samples at all time points were <50. Titers are expressed as geometric means with 95% CL. (E) Serum phagocytic activity (phagocytosis score/background phagocytosis) to gp140 targets 2wkpi in females and males of the gp120- and gp140 immunization groups. (F) Serum ADCC activity of female and male macaques to gp120 and gp140 targets by immunization group at wk 53. (G) Rectal gp120-specific memory B cells (identified by flow cytometry) in female and male macaques of combined gp120- and gp140-immunization groups at 2 wk post-second Env boost (wk 53), 2wkpi, and 8wkpi. Mean values ± SEM are shown in E and G. One gp140-immunized macaque remained uninfected, and is omitted from 2wkpi analyses. In panel G, rectal samples of 15 macaques (6 from each gp120- and gp140-immunization group and 3 controls) are not shown at wk 53 as samples were lost due to a processing error.
Fig 3
Fig 3. Immunological correlates of delayed SIV acquisition.
Influence of rectal Env-specific IgA at wk 55 on the rate of infection in (A) all immunized macaques, (B) in gp120 immunized macaques, and (C) in gp140 immunized macaques. Influence of rectal Env-specific IgA at wk 55 on the rate of infection in (D) all immunized females, (E) in gp120-immunized females, and (F) in gp140-immunized females. gp120 and gp140-immunized macaques were tested against gp120 and gp140 proteins respectively. Control background levels were subtracted prior to analysis. Correlation analysis of Env-specific memory B cells in rectal tissue identified by flow cytometry 2wkpi with number of challenges to become infected in (G) all immunized females, (H) all immunized males, (I) gp120-immunized females, and (J) gp140-immunized females. Correlation analysis of rectal plasma cells identified by flow cytometry 2wkpi with number of challenges to become infected in (K) all immunized females, (L) all immunized males, (M) gp120-immunized females, and (N) gp140-immunized females. One gp140-immunized female remained uninfected and is excluded from the 2wkpi time point in panels G, J, K, and N. In panels K-N, PC were identified following the first challenge using IRF-4 and BCL2 intracellular markers. Subsequently, all data were obtained using the surface marker CD138 and IRF-4. As the two approaches are not comparable, the week one challenge data are omitted.
Fig 4
Fig 4. Viral loads post-infection by immunization group and sex.
(A) Geometric mean plasma viral loads by immunization group. (B-D) Geometric mean plasma viral loads and (E-G) mean CD4 T cell counts in males and females in gp120, gp140, and control macaque groups.
Fig 5
Fig 5. Immunological correlates of viremia control.
Correlation of phagocytic activity (expressed as phagocytosis score/background phagocytosis) of gp140-immunized macaques using gp140 targets 2 weeks post-second Env boost (wk 53) with peak viral load (A). Correlation of phagocytic activity of all macaques 2wkpi with peak viral load (B). Correlation of peripheral EnvsmH4-specific CD8+ TMT cells (% CD8+ TM T cells expressing IL-2, IFN-γ, and TNF-α) in all animals with reduced peak viral load (C) and chronic viremia (median over weeks 8–24) (D). Correlation of EnvsmH4-specific CD8+ TM T cells (% CD8+ TM T cells expressing IL-2, IFN-γ, and TNF-α) 2wkpi in gp140-immunized macaques with (E) peak viral load, (F) acute viral load (geometric mean over weeks 1–6), and (G) chronic viremia (median over weeks 8–24). One gp140-immunized female macaque remained uninfected so is not included in these correlations with viral load. Due to the large number of macaques only half of the macaques in each group were assessed for CD8+ TM T cell SIVsmH4 Env-specificity.
Fig 6
Fig 6. Additional post-infection outcomes by immunization group and sex.
Correlation of the number of challenges required to become infected with peak viremia in all immunized females (A) but not in males (B). (C) Comparison of survival for gp120- and gp140-immunized macaques and control macaques. The overall p value was obtained by a logrank test. All 24 macaques in the gp120 immunization group survived at least 40 weeks, 7 of the 23 infected macaques in the gp140 group were euthanized between weeks 19 and 39, and 2 of 12 controls were euthanized between weeks 36 and 39. (D) Survival of female and male macaques in the gp140 group. Five of the 15 infected females were euthanized between weeks 19 and 39; 2 of 8 males were euthanized between weeks 28 and 39.
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References

    1. Klein SL. Sex influences immune responses to viruses, and efficacy of prophylaxis and treatments for viral diseases. Bioessays. 2012; 34: 1050–1059. 10.1002/bies.201200099 - DOI - PMC - PubMed
    1. Addo MM, Altfeld M. Sex-based differences in HIV type 1 pathogenesis. J Infec Dis. 2014; 209 (Suppl 3): S86–S92. - PMC - PubMed
    1. Farzadegan H, Hoover DR, Astemborski J, Lyles CM, Margolick JB, Markham RB, et al. Sex differences in HIV-1 viral load and progression to AIDS. The Lancet. 1998; 352: 1510–1514. - PubMed
    1. Patterson LJ, Kuate S, Daltabuit-Test M, Li Q, Xiao P, McKinnon K, et al. Replicating adenovirus-simian immunodeficiency virus (SIV) vectors efficiently prime SIV-specific systemic and mucosal immune responses by targeting myeloid dendritic cells and persisting in rectal macrophages, regardless of immunization route. Clin Vac Immunol. 2012; 19: 629–637. - PMC - PubMed
    1. Rerks-Ngarm S, Pitisuttithum P, Nitayaphan S, Kaewkungwal J, Chiu J, Paris R, et al. Vaccination with ALVAC and AIDSVAX to prevent HIV-1 infection in Thailand. N Engl J Med. 2009; 361: 2209–2220. 10.1056/NEJMoa0908492 - DOI - PubMed

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