BackgroundMaternal viral infection during pregnancy is associated with an increase in the incidence of psychiatric disorders with presumed neurodevelopmental origin, including autism spectrum disorders and schizophrenia. The enhanced risk for developing mental illness appears to be caused by deleterious effects of innate immune response-associated factors on the development of the central nervous system, which predispose the offspring to pathological behaviors in adolescence and adulthood. To identify the immune response-associated soluble factors that may affect central nervous system development, we examined the effect of innate immune response activation by polyriboinosinic-polyribocytidylic acid (poly(I:C)), a synthetic analogue of viral double-stranded RNA, on the expression levels of pro- and anti-inflammatory cytokines, chemokines and colony stimulating factors in fetal and postnatal mouse brain 6 h and 24 h after treatment.MethodsC57BL/6J pregnant mice (gestational day 16) or newborn mice (postnatal day 4) received a single intraperitoneal injection of the synthetic analogue of viral double-stranded RNA poly(I:C) (20 mg/kg). Thirty-two immune response-associated soluble factors, including pro- and anti-inflammatory cytokines, chemokines and colony stimulating factors, were assayed 6 h and 24 h after poly(I:C) injection using multiplexed bead-based immunoassay (Milliplex Map) and processed in a Luminex 100 IS instrument.ResultsMaternal exposure to poly(I:C) at gestational day 16 induced a significant increase in cytokines interleukin (IL)-1β, IL-7 and IL-13; chemokines monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein (MIP)-1α, interferon gamma-induced protein (IP)-10 and monokine induced by IFN-gamma (MIG); and in the colony stimulating factor vascular endothelial growth factor (VEGF) in the fetal brain. IL-1β showed the highest concentration levels in fetal brains and was the only cytokine significantly up-regulated 24 h after maternal poly(I:C) injection, suggesting that IL-1β may have a deleterious impact on central nervous system development. In contrast, poly(I:C) treatment of postnatal day 4 pups induced a pronounced rise in chemokines and colony stimulating factors in their brains instead of the pro-inflammatory cytokine IL-1β.ConclusionsThis study identified a significant increase in the concentration levels of the cytokines IL-1β and IL-13, the chemokine MCP-1 and the colony stimulating factor VEGF in the developing central nervous system during activation of an innate immune response, suggesting that these factors are mediators of the noxious effects of maternal immune activation on central nervous system development, with potential long-lasting effects on animal behavior.

Infusion of a simianized anti-αβ mAb (Rh-αβ) just before and following SIV infection protected rhesus macaques from developing AIDS and partially from vaginal SIV acquisition. Recently, short-term treatment with Rh-αβ in combination with cART was found to lead to prolonged viral suppression after withdrawal of all therapeutic interventions. The humanized form of Rh-αβ, vedolizumab, is a highly effective treatment for inflammatory bowel disease. To clarify the mechanism of action of Rh-αβ, naive macaques were infused with Rh-αβ and sampled in blood and tissues before and after treatment to monitor several immune cell subsets. In blood, Rh-αβ increased the CD4 and CD8 T cell counts, but not B cell counts, and preferentially increased CCR6 subsets while decreasing CD103 and CD69 lymphocytes. In mucosal tissues, surprisingly, Rh-αβ did not impact integrin α cells, but decreased the frequencies of CCR6 and CD69 CD4 T cells and, in the gut, Rh-αβ transiently decreased the frequency of memory and IgA B cells. In summary, even in the absence of inflammation, Rh-αβ impacted selected immune cell subsets in different tissues. These data provide new insights into the mechanisms by which Rh-αβ may mediate its effect in SIV-infected macaques with implications for understanding the effect of treatment with vedolizumab in patients with inflammatory bowel disease.

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Prevention of HIV acquisition and replication requires long lasting and effective immunity. Given the state of HIV vaccine development, innovative vectors and immunization strategies are urgently needed to generate safe and efficacious HIV vaccines. Here, we developed a novel lentivirus-based DNA vector that does not integrate in the host genome and undergoes a single-cycle of replication. Viral proteins are constitutively expressed under the control of Tat-independent LTR promoter from goat lentivirus. We immunized six macaques once only with CAL-SHIV-IN− DNA using combined intramuscular and intradermal injections plus electroporation. Antigen-specific T cell responses were monitored for 47 weeks post-immunization (PI). PBMCs were assessed directly ex vivo or after 6 and 12 days of in vitro culture using antigenic and/or homeostatic proliferation. IFN-γ ELISPOT was used to measure immediate cytokine secretion from antigen specific effector cells and from memory precursors with high proliferative capacity (PHPC). The memory phenotype and functions (proliferation, cytokine expression, lytic content) of specific T cells were tested using multiparametric FACS-based assays. All immunized macaques developed lasting peripheral CD8+ and CD4+ T cell responses mainly against Gag and Nef antigens. During the primary expansion phase, immediate effector cells as well as increasing numbers of proliferating cells with limited effector functions were detected which expressed markers of effector (EM) and central (CM) memory phenotypes. These responses contracted but then reemerged later in absence of antigen boost. Strong PHPC responses comprising vaccine-specific CM and EM T cells that readily expanded and acquired immediate effector functions were detected at 40/47 weeks PI. Altogether, our study demonstrated that a single immunization with a replication-limited DNA vaccine elicited persistent vaccine-specific CM and EM CD8+ and CD4+ T cells with immediate and readily inducible effector functions, in the absence of ongoing antigen expression.

VRC01 protects macaques from vaginal SHIV infection after a single high-dose challenge. Infusion of a simianized anti-α 4 β 7 mAb (Rh-α 4 β 7 ) just prior to, and during repeated vaginal exposures to SIVmac251 partially protected macaques from vaginal SIV infection and rescued CD4 + T cells. To investigate the impact of combining VRC01 and Rh-α 4 β 7 on SHIV infection, 3 groups of macaques were treated with a suboptimal dosing of VRC01 alone or in combination with Rh-α 4 β 7 or with control antibodies prior to the initiation of weekly vaginal exposures to a high dose (1000 TCID 50 ) of SHIV AD8-EO . The combination Rh-α 4 β 7 -VRC01 significantly delayed SHIV AD8-EO vaginal infection. Following infection, VRC01-Rh-α 4 β 7 -treated macaques maintained higher CD4 + T cell counts and exhibited lower rectal SIV-DNA loads compared to controls. Interestingly, VRC01-Rh-α 4 β 7 -treated macaques had fewer IL-17-producing cells in the blood and the gut during the acute phase of infection. Moreover, higher T cell responses to the V2-loop of the SHIV AD8-EO envelope in the VRC01-Rh-α 4 β 7 group inversely correlated with set point viremia. The combination of suboptimal amounts of VRC01 and Rh-α 4 β 7 delayed infection, altered antiviral immune responses and minimized CD4 + T cell loss. Further exploration of the effect of combining bNAbs with Rh-α 4 β 7 on SIV/HIV infection and antiviral immune responses is warranted and may lead to novel preventive and therapeutic strategies.

Increasing the safety and the efficacy of existing HIV vaccines is one of the strategies that could help to promote the development of a vaccine for human use. We developed a HIV DNA vaccine (Δ4-SHIVku2) that has been shown to induce potent polyfunctional HIV-specific T cell responses following a single dose immunization of mice and macaques. Δ4-SHIVku2 also induced protection when immunized macaques were challenged with homologous pathogenic viruses. In the present study, our aim was to examine whether a chimeric HIV DNA vaccine (CAL-Δ4-SHIVku2) whose genome is driven by the LTR of the goat lentivirus, caprine arthritis encephalitis (CAEV) expresses efficiently the vaccine antigens and induces potent immune responses in animal models for HIV vaccine. Data of radioimmunoprecipitation assays clearly show that this chimeric genome drives efficient expression of all HIV antigens in the construct. In addition, evaluation of the p24 Gag protein in the supernatant of HEK-293-T cells transfected in parallel with Δ4-SHIVku2 and CAL-Δ4-SHIVku2 showed no difference suggesting that these two LTRs are inducing equally the expression of the viral genes. Immunization of mice and macaques using our single dose immunization regimen resulted in induction of similar IFN-γ ELISPOT responses in Δ4-SHIVku2- and CAL-Δ4-SHIVku2-treated mice. Similar profiles of T cell responses were also detected both in mice and macaques when multiparametric flow cytometry analyses were performed. Since CAEV LTR is not dependent of Tat to drive viral gene expression and is not functional for integration with HIV integrase, this new vector increases the safety and efficacy of our vaccine vectors and vaccination strategy.

Background Although HSV-2 is the major cause of genital lesions, HSV-1 accounts for half of new cases in developed countries. Methods Three healthy SHIV-SF162P3 infected Indian rhesus macaques were inoculated with 4x108 pfu of HSV-1 twice, with the second inoculation performed after the vaginal mucosa was gently abraded with a cytobrush. Results HSV-1 DNA was detected in vaginal swabs 5 days after the 2nd, but not the 1st inoculation in all 3 macaques. An increase in inflammatory cytokines was detected in the vaginal fluids of the animals with no or intermittent shedding. Higher frequency of blood α4β7high CD4+ T cells was measured in the animals with consistent and intermitted shedding, while a decrease in the frequency of CD69+ CD4+ T cells was present in all animals. Conclusions This macaque model of genital HSV-1 could be useful to study the impact of the growing epidemic of genital HSV-1 on HIV infection.

Mucosal HIV-1 transmission is inefficient. However, certain viral and host characteristics may play a role in facilitating HIV acquisition and systemic expansion. Cells expressing high levels of integrin α4β7 have been implicated in favoring the transmission process and the infusion of an anti-α4β7 mAb (RM-Act-1) prior to, and during a repeated low-dose vaginal challenge (RLDC) regimen with SIVmac251 reduced SIV acquisition and protected the gut-associated lymphoid tissues (GALT) in the macaques that acquired SIV. α4β7 expression is required for lymphocyte trafficking to the gut lamina propria and gut inductive sites. Several therapeutic strategies that target α4β7 have been shown to be effective in treating inflammatory conditions of the intestine, such as inflammatory bowel disease (IBD). To determine if blocking α4β7 with ELN, an orally available anti-α4 small molecule, would inhibit SHIV-SF162P3 acquisition, we tested its ability to block MAdCAM-1 (α4β7 natural ligand) and HIV-gp120 binding in vitro. We studied the pharmacokinetic profile of ELN after oral and vaginal delivery in macaques. Twenty-six macaques were divided into 3 groups: 9 animals were treated with ELN orally, 9 orally and vaginally and 8 were used as controls. All animals were challenged intra-vaginally with SHIV-SF162P3 using the RLDC regimen. We found that ELN did not protect macaques from SHIV acquisition although it reduced the SHIV-induced inflammatory status during the acute phase of infection. Notably, integrins can exist in different activation states and, comparing the effect of ELN and the anti-α4β7 mAb RM-Act-1 that reduced susceptibility to SIV infection, we determined that ELN induces the active conformation of α4β7, while RM-Act-1 inhibits its activation through an allosteric mechanism. These results suggest that inhibition of α4β7 activation may be necessary to reduce susceptibility to SIV/SHIV infection and highlight the complexity of anti-integrins therapeutic approach in HIV as well as in IBD and other autoimmune diseases.