Anti-HIV and -SIV immunity in the vagina

Long-term antibody production and viremia in American mink (Neovison vison) challenged with Aleutian mink disease virus

Background

Selecting American mink (Neovison vison) for tolerance to Aleutian mink disease virus (AMDV) has gained popularity in recent years, but data on the outcomes of this activity are scant. The objectives of this study were to determine the long-term changes in viremia, seroconversion and survival in infected mink. Mink were inoculated intranasally with a local isolate of Aleutian mink disease virus (AMDV) over 4 years (n = 1742). The animals had been selected for tolerance to AMDV for more than 20 years (TG100) or were from herds free of AMDV (TG0). The progenies of TG100 and TG0, and their crosses with 25, 50 and 75% tolerance ancestry were also used. Blood samples were collected from each mink up to 14 times until 1211 days post-inoculation (dpi) and were tested for viremia by PCR and for anti-AMDV antibodies by counter-immunoelectrophoresis (CIEP). Viremia and CIEP status were not considered when selecting replacements. Low-performing animals were pelted and the presence of antibodies in their blood and antibody titer were measured by CIEP, and viremia and viral DNA in seven organs (n = 936) were tested by PCR.

Results

The peak incidences of viremia (66.7%) and seropositivity (93.5%) were at 35 dpi. The incidence of viremia decreased over time while the incidence of seroconversion increased. The least-squares means of the incidence of PCR positive of lymph node (0.743) and spleen (0.656) were significantly greater than those of bone marrow, liver, kidneys, lungs and small intestine (0.194 to 0.342). Differences in tolerant ancestry were significant for every trait measured. Incidences of viremia over time, terminal viremia, seropositivity over time, AMDV DNA in organs and antibody titer were highest in the susceptible groups (TG0 or TG25) and lowest in the tolerant groups (TG100 or TG75).

Conclusion

Previous history of selection for tolerance resulted in mink with reduced viral replication and antibody titer. Viremia had a negative effect and antibody production had a positive effect on survival and productivity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03462-7.

A comparison between intraperitoneal injection and intranasal and oral inoculation of mink with Aleutian mink disease virus

Intranasal, with (INS) and without (IN) sedation, and oral inoculation were compared with intraperitoneal (IP) injection for establishing infection with a local isolate of Aleutian mink disease virus (AMDV) in 35 American mink. Blood samples were collected on 0, 21, 36 and 56 day post-inoculation (dpi). Antiviral-antibodies and viral DNA in plasma and tissues were measured by counter-immunoelectrophoresis (CIEP) and PCR, respectively. The presence of AMDV DNA was tested by PCR in saliva, rectal and fecal samples collected on 0, 6, 10, 15, 21, 28, 36 and 56 dpi. Animals were killed at 56 dpi, samples of six organs were tested for antibody and AMDV DNA, and samples of the lungs, liver, kidneys and heart were subjected to histology. Viral DNA was detected in the spleen, lungs and lymph nodes of all inoculated mink on 56 dpi, indicating that all inoculation routes caused infection in mink. Viral DNA and antibodies were detected in plasma of all IP and INS inoculated mink by 36 dpi, but some animals which were inoculated orally or via IN remained seronegative by 56 dpi. It was concluded that INS route was the most effective method for establishing infection in mink without breaking the integrity of the animals' anatomical barriers. Viremia was short-lived in some mink, whereas antibody production persisted in seroconverted animals during the duration of the experiment. Saliva, rectal and fecal samples did not accurately detect infection. Histologic lesions of AD were observed on the four organs of most mink.

Zika virus preferentially replicates in the female reproductive tract after vaginal inoculation of rhesus macaques

Zika virus (ZIKV) is a mosquito-transmitted virus that can cause severe defects in an infected fetus. ZIKV is also transmitted by sexual contact, although the relative importance of sexual transmission is unclear. To better understand the role of sexual transmission in ZIKV pathogenesis, a nonhuman primate (NHP) model of vaginal transmission was developed. ZIKV was readily transmitted to mature cycling female rhesus macaque (RM) by vaginal inoculation with 10⁴–10⁶ plaque-forming units (PFU). However, there was variability in susceptibility between the individual RM with 1–>8 vaginal inoculations required to establish infection. After treatment with Depoprovera, a widely used contraceptive progestin, two RM that initially resisted 8 vaginal ZIKV inoculations became infected after one ZIKV inoculation. Thus, Depoprovera seemed to enhance susceptibility to vaginal ZIKV transmission. Unexpectedly, the kinetics of virus replication and dissemination after intravaginal ZIKV inoculation were markedly different from RM infected with ZIKV by subcutaneous (SQ) virus inoculation. Several groups have reported that after SQ ZIKV inoculation vRNA is rapidly detected in blood plasma with vRNA less common in urine and saliva and only rarely detected in female reproductive tract (FRT) secretions. In contrast, in vaginally inoculated RM, plasma vRNA is delayed for several days and ZIKV replication in, and vRNA shedding from, the FRT was found in all 6 animals. Further, after intravaginal transmission ZIKV RNA shedding from FRT secretions was detected before or simultaneously with plasma vRNA, and persisted for at least as long. Thus, ZIKV replication in the FRT was independent of, and often preceded virus replication in the tissues contributing to plasma vRNA. These results support the conclusion that ZIKV preferentially replicates in the FRT after vaginal transmission, but not after SQ transmission, and raise the possibility that there is enhanced fetal infection and pathology after vaginal ZIKV transmission compared to a mosquito transmitted ZIKV.

Zika virus was introduced to Brazil in 2015 and it rapidly spread to all of tropical America. Although Zika virus infection is usually mild in adults, it can cause severe birth defects in the developing fetus that makes it critical to prevent ZIKV infection in women who are pregnant or who could become pregnant. Although Zika virus is transmitted primarily by mosquito bite, it can also be transmitted by sex. To understand the role of sexual transmission in Zika virus disease, we inoculated rhesus monkeys intravaginally with the virus and monitored virus in blood and reproductive tract secretions. ZIKV was detected in the female reproductive tract before it was detected in plasma and replication levels in the female reproductive tract did not reflect ZIKV levels in other parts of the body. Thus ZIKV prefers the reproductive tract after vaginal transmission suggesting that fetal disease could be more common or severe after vaginal ZIKV transmission compared to a mosquito transmitted ZIKV infection.

Oral Mucosal Immunity and HIV/SIV Infection

Human Immunodeficiency Virus (HIV) transmission through genital and rectal mucosa has led to intensive study of mucosal immune responses to HIV and to the development of a vaccine administered locally. However, HIV transmission through the oral mucosa is a rare event. The oral mucosa represents a physical barrier and contains immunological elements to prevent the invasion of pathogenic organisms. This particular defense differs between micro-compartments represented by the salivary glands, oral mucosa, and palatine tonsils. Secretory immunity of the salivary glands, unique features of cellular structure in the oral mucosa and palatine tonsils, the high rate of oral blood flow, and innate factors in saliva may all contribute to the resistance to HIV/Simian Immunodeficiency Virus (SIV) oral mucosal infection. In the early stage of HIV infection, humoral and cellular immunity and innate immune functions in oral mucosa are maintained. However, these particular immune responses may all be impaired as a result of chronic HIV infection. A better understanding of oral mucosal immune mechanisms should lead to improved prevention of viral and bacterial infections, particularly in immunocompromised persons with Acquired Immune Deficiency Syndrome (AIDS), and to the development of a novel strategy for a mucosal AIDS vaccine, as well as vaccines to combat other oral diseases, such as dental caries and periodontal diseases.

Transcriptional profiling of peripheral CD8+T cell responses to SIVΔnef and SIVmac251 challenge reveals a link between protective immunity and induction of systemic immunoregulatory mechanisms

Immunization of macaques with attenuated simian immunodeficiency virus (SIV) with deletions in nef (SIVΔnef) is shown to elicit protective immunity to infection by pathogenic SIV, yet the mechanisms that orchestrate protection and prevent pathogenesis remains unknown. We utilized whole-genome transcriptional profiling to reveal molecular signatures of protective immunity in circulating CD8+ T cells of rhesus macaques vaccinated with SIVmac239Δnef and challenged with pathogenic SIVmac251. Our findings suggest that protective immunity to pathogenic SIV infection induced by SIVmac239∆nef is associated with balanced induction of T cell activation and immunoregulatory mechanisms and dampened activation of interferon-induced signaling pathways and cytolytic enzyme production as compared with pathogenic SIVmac251 infection of unvaccinated controls. We provide evidence that protective immunity to SIVmac251 correlates with induction of biomarkers of T cell activation, differentiation, signaling, and adhesion that were down regulated in unvaccinated controls. The study highlights potential immunomodulatory networks associated with protective immunity against the virus.

Induction of Potent and Long-Lived Antibody and Cellular Immune Responses in the Genitorectal Mucosa Could be the Critical Determinant of HIV Vaccine Efficacy

The field of HIV prevention has indeed progressed in leaps and bounds, but with major limitations of the current prevention and treatment options, the world remains desperate for an HIV vaccine. Sadly, this continues to be elusive, because more than 30 years since its discovery there is no licensed HIV vaccine. Research aiming to define immunological biomarkers to accurately predict vaccine efficacy have focused mainly on systemic immune responses, and as such, studies defining correlates of protection in the genitorectal mucosa, the primary target site for HIV entry and seeding are sparse. Clearly, difficulties in sampling and analysis of mucosal specimens, as well as their limited size have been a major deterrent in characterizing the type (mucosal antibodies, cytokines, chemokines, or CTL), threshold (magnitude, depth, and breadth) and viral inhibitory capacity of HIV-1-specific immune responses in the genitorectal mucosa, where they are needed to immediately block HIV acquisition and arrest subsequent virus dissemination. Nevertheless, a few studies document the existence of HIV-specific immune responses in the genitorectal mucosa of HIV-infected aviremic and viremic controllers, as well as in highly exposed persistently seronegative (HEPS) individuals with natural resistance to HIV-1. Some of these responses strongly correlate with protection from HIV acquisition and/or disease progression, thus providing significant clues of the ideal components of an efficacious HIV vaccine. In this study, we provide an overview of the key features of protective immune responses found in HEPS, elite and viremic controllers, and discuss how these can be achieved through mucosal immunization. Inevitably, HIV vaccine development research will have to consider strategies that elicit potent antibody and cellular immune responses within the genitorectal mucosa or induction of systemic immune cells with an inherent potential to home and persist at mucosal sites of HIV entry.

Blocking of integrins inhibits HIV-1 infection of human cervical mucosa immune cells with free and complement-opsonized virions

The initial interaction between HIV-1 and the host occurs at the mucosa during sexual intercourse. In cervical mucosa, HIV-1 exists both as free and opsonized virions and this might influence initial infection. We used cervical explants to study HIV-1 transmission, the effects of opsonization on infectivity, and how infection can be prevented. Complement opsonization enhanced HIV-1 infection of dendritic cells (DCs) compared with that by free HIV-1, but this increased infection was not observed with CD4(+) T cells. Blockage of the α4-, β7-, and β1-integrins significantly inhibited HIV-1 infection of both DCs and CD4(+) T cells. We found a greater impairment of HIV-1 infection in DCs for complement-opsonized virions compared with that of free virions when αM/β2- and α4-integrins were blocked. Blocking the C-type lectin receptor macrophage mannose receptor (MMR) inhibited infection of emigrating DCs but had no effect on CD4(+) T-cell infection. We show that blocking of integrins decreases the HIV-1 infection of both mucosal DCs and CD4(+) T cells emigrating from the cervical tissues. These findings may provide the basis of novel microbicidal strategies that may help limit or prevent initial infection of the cervical mucosa, thereby reducing or averting systemic HIV-1 infection.

Antibody responses after intravaginal immunisation with trimeric HIV-1 CN54 clade C gp140 in Carbopol gel are augmented by systemic priming or boosting with an adjuvanted formulation

Optimum strategies to elicit and maintain antibodies at mucosal portals of virus entry are critical for the development of vaccines against human immunodeficiency virus (HIV). Here we show in non-human primates that a novel regimen of repeated intravaginal delivery of a non-adjuvanted, soluble recombinant trimeric HIV-1_CN54 clade C envelope glycoprotein (gp140) administered in Carbopol gel can prime for B-cell responses even in the absence of seroconversion. Following 3 cycles of repeated intravaginal administration, throughout each intermenses interval, 3 of 4 macaques produced or boosted systemic and mucosally-detected antibodies upon intramuscular immunisation with gp140 formulated in AS01 adjuvant. Reciprocally, a single intramuscular immunisation primed 3 of 4 macaques for antibody boosting after a single cycle of intravaginal immunisation. Virus neutralising activity was detected against clade C and clade B HIV-1 envelopes but was restricted to highly neutralisation sensitive pseudoviruses.

Mucosal HIV transmission and vaccination strategies through oral compared with vaginal and rectal routes

IMPORTANCE OF THE FIELD

There are currently over thirty million people infected with HIV and there are no vaccines available to prevent HIV infections or disease. The genitourinary, rectal and oral mucosa are the mucosal HIV transmission routes. An effective vaccine that can induce both systemic and local mucosal immunity is generally accepted as a major means of protection against mucosal HIV transmission and AIDS.

WHAT THE READER WILL GAIN

Structure and cells that comprise the oral, vaginal and rectal mucosa pertaining to HIV transmission and vaccination strategies through each mucosal route to prevent mucosal and systemic infection will be discussed.

AREAS COVERED IN THIS REVIEW

Covering publications from 1980s through 2010, mucosal transmission of HIV and current and previous approaches to vaccinations are discussed.

TAKE HOME MESSAGE

Although oral transmission of HIV is far less common than vaginal and rectal transmissions, infections through this route do occur through oral sex as well as vertically from mother to child. Mucosal vaccination strategies against oral and other mucosal HIV transmissions are under intensive research but the lack of consensus on immune correlates of protection and lack of safe and effective mucosal adjuvants and delivery systems hamper progress towards a licensed vaccine.

gp340 promotes transcytosis of human immunodeficiency virus type 1 in genital tract-derived cell lines and primary endocervical tissue

The human scavenger receptor gp340 has been identified as a binding protein for the human immunodeficiency virus type 1 (HIV-1) envelope that is expressed on the cell surface of female genital tract epithelial cells. This interaction allows such epithelial cells to efficiently transmit infective virus to susceptible targets and maintain viral infectivity for several days. Within the context of vaginal transmission, HIV must first traverse a normally protective mucosa containing a cell barrier to reach the underlying T cells and dendritic cells, which propagate and spread the infection. The mechanism by which HIV-1 can bypass an otherwise healthy cellular barrier remains an important area of study. Here, we demonstrate that genital tract-derived cell lines and primary human endocervical tissue can support direct transcytosis of cell-free virus from the apical to basolateral surfaces. Further, this transport of virus can be blocked through the addition of antibodies or peptides that directly block the interaction of gp340 with the HIV-1 envelope, if added prior to viral pulsing on the apical side of the cell or tissue barrier. Our data support a role for the previously described heparan sulfate moieties in mediating this transcytosis but add gp340 as an important facilitator of HIV-1 transcytosis across genital tract tissue. This study demonstrates that HIV-1 actively traverses the protective barriers of the human genital tract and presents a second mechanism whereby gp340 can promote heterosexual transmission.

Antiviral CD8+ T cells in the genital tract control viral replication and delay progression to AIDS after vaginal SIV challenge in rhesus macaques immunized with virulence attenuated SHIV 89.6

The recently failed clinical efficacy trial of an acquired immunodeficiency syndrome (AIDS) vaccine that elicits antiviral CD8(+) T-cell responses has emphasized the challenge of producing an effective vaccine against human immunodeficiency virus (HIV). In the simian immunodeficiency virus (SIV)/ rhesus monkey model of AIDS, live-attenuated lentivirus 'vaccines' provide the best protection from uncontrolled viral replication and clinical disease after pathogenic SIV challenge. This review summarizes a recent series of studies in which we show that after vaginal SIV challenge of rhesus macaques immunized with an attenuated lentivirus protection from uncontrolled viral replication is primarily mediated by CD8(+) T cells in the vaginal mucosa. Immunization with a chimeric simian/human immunodeficiency virus (SHIV) results in a systemic infection that induces a moderate population of SIV-specific CD8(+) and CD4(+) T cells with cytolytic potential in the vaginal mucosa. Depletion of CD8(+) T cells at the time of SIV challenge completely abrogates the protection mediated by prior infection with attenuated SHIV. Further after vaginal SIV challenge, the only significant expansion of SIV-specific T cells occurs in the vagina in these animals. No significant expansion of T-cell responses was observed in systemic lymphoid tissues. Thus, the presence of SIV-specific CD8(+) T cells in the vagina on the day of vaginal SIV challenge and a modest expansion of local effector T cells is sufficient to stop uncontrolled SIV replication. It seems that T-cell based vaccine strategies that can elicit mucosal effector CD8(+) T-cell populations and avoid inducing systemic T-cell proliferation upon exposure to HIV have the greatest potential for mimicking the success of live-attenuated lentiviral vaccines.

Morphologic and Immunohistochemical Features of the Cynomolgus Macaque Cervix

Female macaques serve as an important model for the study of reproductive diseases in women. Here we summarize characteristics of the macaque cervix, with a particular emphasis on the cynomolgus macaque. Key anatomic features include a stratified squamous exocervix, squamocolumnar junction and transformation zone, and glandular endocervix with prominent colliculi. Endocervical eversion occurs with onset of ovarian cycling and regresses to varying degrees based on age, hormonal status, and individual conformation. The cervical epithelium in macaques is highly responsive to estrogens, which induce marked squamous epithelial maturation and glandular hypertrophy. Progestogen effects include further induction of endocervical secretory activity and release of viscous mucus, which functions in both mucosal immunity and fertility regulation. On immunohistochemistry, the squamous cervix shows strong expression of estrogen receptor α, the proliferation marker Ki67/MIB1, and cytokeratin 14, whereas endocervical epithelium strongly expresses estrogen and progesterone receptors and cytokeratins 18 and 19. These patterns of expression are altered in cervical intraepithelial neoplasia, which is a common spontaneous lesion of the macaque cervix associated with specific types of oncogenic papillomaviruses. This report highlights important similarities with human cervix that should be useful for future studies of genital infection, neoplasia, and immunity in the macaque model.

Competing Interests: This article was sponsored by Covance Inc. and Schering-Plough. The author did not declare any other competing interests.

Selected Background Findings and Interpretation of Common Lesions in the Female Reproductive System in Macaques

The authors describe a selection of normal findings and common naturally occurring lesions in the reproductive system of female macaques, including changes in the ovaries, uterus, cervix, vagina, and mammary glands. Normal features of immature ovaries, uteri, and mammary glands are described. Common non-neoplastic lesions in the ovaries include cortical mineralization, polyovular follicles, cysts, ovarian surface epithelial hyperplasia, and ectopic ovarian tissue. Ovarian neoplasms include granulosa cell tumors, teratomas, and ovarian surface epithelial tumors. Common non-neoplastic uterine findings include loss of features of normal cyclicity, abnormal bleeding, adenomyosis, endometriosis, epithelial plaques, and pregnancy-associated vascular remodeling. Hyperplastic and neoplastic lesions of the uterus include endometrial polyps, leiomyomas, and rarely endometrial hyperplasia and endometrial adenocarcinoma. Vaginitis is common. Cervical lesions include endocervical squamous metaplasia, polyps, and papillomavirus-associated lesions. Lesions in the mammary gland are most often proliferative and range from ductal hyperplasia to invasive carcinoma. Challenges to interpretation include the normal or pathologic absence of menstrual cyclicity and the potential misinterpretation of sporadic lesions, such as epithelial plaques or papillomavirus-associated lesions. Interpretation of normal and pathologic findings is best accomplished with knowledge of the life stage, reproductive history, and hormonal status of the animal.

Protective attenuated lentivirus immunization induces SIV-specific T cells in the genital tract of rhesus monkeys

Live attenuated lentivirus immunization is the only vaccine strategy that elicits consistent protection against intravaginal challenge with pathogenic simian immunodeficiency virus (SIV). To determine the mechanism of protection in rhesus monkeys infected with attenuated simian-human immunodeficiency virus (SHIV)89.6, a detailed analysis of SIV Gag-specific T-cell responses in several tissues including the genital tract was performed. Six months after SHIV infection, antiviral T-cell responses were rare in the cervix; however, polyfunctional, cytokine-secreting, and degranulating SIV Gag-specific CD4(+) T cells were consistently found in the vagina of the immunized macaques. SIV-specific CD8(+) T cells were also detected in the vagina, blood, and genital lymph nodes of most of the animals. Thus, an attenuated SHIV vaccine induces persistent antiviral T cells in tissues, including the vagina, where these effector T-cell responses may mediate the consistent protection from vaginal SIV challenge observed in this model.

Beta7-integrin-independent enhancement of mucosal and systemic anti-HIV antibody responses following combined mucosal and systemic gene delivery

Vaccination strategies that can block or limit heterosexual human immunodeficiency virus (HIV) transmissions to local and systemic tissues are the goal of much research effort. Herein, in a mouse model, we aimed to determine whether the enhancement of antibody responses through mucosal and systemic immunizations, previously observed with protein-based vaccines, applies to immunizations with DNA- or RNA-based vectors. Intranasal (i.n.) followed by intramuscular (i.m.) immunizations (i.n./i.m.) with polylactide-coglycolide (PLG)-DNA microparticles encoding HIV-gag (PLG-DNA-gag) significantly enhanced serum antibody responses, compared with i.m., i.n. or i.m. followed by i.n. (i.m./i.n.) immunizations. Moreover, while i.n./i.m., i.n. or i.m./i.n. immunizations with PLG-DNA-gag resulted in genital tract antibody responses, i.m. immunizations alone failed to do so. Importantly, beta7-deficient mice developed local and systemic antibody responses following i.n./i.m. immunization, or immunization via any other route, similar to those of wild-type mice. To compare the DNA with an RNA delivery system, immunizations were performed with VEE/SIN-gag replicon particles, composed of Venezuelan equine encephalitis virus (VEE) replicon RNA and Sindbis surface structure (SIN). i.n./i.m., compared with any other immunizations, i.n./i.m. immunization with VEE/SIN-gag resulted in enhanced genital tract but not serum antibody responses. These data show for the first time that mucosal followed by systemic immunizations with gene delivery systems enhance B-cell responses independent of the mucosal homing receptors alpha4beta7 and alphaEbeta7.

Efficient repeated low-dose intravaginal infection with X4 and R5 SHIVs in rhesus macaque: implications for HIV-1 transmission in humans

We examined the effect of inoculum dose on SHIV transmission and infection. We found that repeated low-dose intravaginal exposure with either R5-SHIV(SF162P3) or X4-SHIV(SF33A) results in infections that are blunted and rapidly controlled. Interestingly, although the transmission rate after all repeated exposures is comparable for the two viruses, the probability of low-dose vaginal transmission is greater for the X4 than R5 virus. Furthermore, X4-SHIV(SF33A) replication predominates in low-dose dually-exposed macaques, suggesting that it is better at establishing a systemic infection following transmission. However, X4-SHIV(SF33A) advantage in transmission and infection is not observed in macaques inoculated intravenously with low-dose mixed inoculum. The finding that although matched in tissue culture infectious dose, the X4 inoculum is more complex leads us to hypothesize that the greater genetic heterogeneity of the X4 virus population may have rendered it less susceptible to the severe bottleneck effects imposed by IVAG inoculation with small doses, allowing for greater probability of transmission and establishment of a generalized infection. These data have implications for HIV-1 transmission and infection in humans.

Perils at mucosal front lines for HIV and SIV and their hosts

HIV-1 and simian immunodeficiency virus (SIV), as well as their hosts, face perils at mucosal front lines in early infection. At these sites, 'resting' CD4+ memory T cells fuel infection (because they are hosts for virus), depleting CD4+ memory T cells throughout the lymphoid tissues, particularly in the gut, and eliciting an immunosuppressive regulatory T-cell response that impairs host defence. But HIV-1 and SIV also risk elimination at the earliest stage of infection, at the mucosal point of entry, if founder populations of infected cells do not expand sufficiently to establish a self-propagating infection. Microbicides and vaccines could increase these viral vulnerabilities at mucosal front lines.

Characterization of human immunodeficiency virus Gag-specific gamma interferon-expressing cells following protective mucosal immunization with alphavirus replicon particles

A safe, replication-defective viral vector that can induce mucosal and systemic immune responses and confer protection against many infectious pathogens, such as human immunodeficiency virus type 1 (HIV-1), may be an ideal vaccine platform. Accordingly, we have generated and tested alphavirus replicon particles encoding HIV-1 Gag from Sindbis virus (SIN-Gag) and Venezuelan equine encephalitis virus (VEE-Gag), as well as chimeras between the two (VEE/SIN-Gag). Following intramuscular (i.m.), intranasal (i.n.), or intravaginal (IVAG) immunization with VEE/SIN-Gag and an IVAG challenge with vaccinia virus encoding HIV Gag (VV-Gag), a larger number of Gag-specific CD8+ intracellular gamma interferon-expressing cells (iIFNEC) were detected in iliac lymph nodes (ILN), which drain the vaginal/uterine mucosa (VUM), than were observed after immunizations with SIN-Gag. Moreover, a single i.n. or IVAG immunization with VEE/SIN-Gag induced a larger number of cells expressing HIV Gag in ILN, and immunizations with VEE/SIN-Gag through any route induced better protective responses than immunizations with SIN-Gag. In VUM, a larger percentage of iIFNEC expressed alpha4beta7 or alpha(Ebeta)7 integrin than expressed CD62L integrin. However, in spleens (SP), a larger percentage of iIFNEC expressed alpha4beta7 or CD62L than expressed alpha(Ebeta)7. Moreover, a larger percentage of iIFNEC expressed the chemokine receptor CCR5 in VUM and ILN than in SP. These results demonstrate a better induction of cellular and protective responses following immunizations with VEE/SIN-Gag than that following immunizations with SIN-Gag and also indicate a differential expression of homing and chemokine receptors on iIFNEC in mucosal effector and inductive sites versus systemic lymphoid tissues.

Mucosal and systemic anti-HIV responses in rhesus macaques following combinations of intranasal and parenteral immunizations

There is an urgent need to develop vaccines that can elicit immunological memory responses against HIV. Using the rhesus macaque model and a combination of intranasal (IN) and parenteral immunizations with DNA or protein adsorbed to microparticles or mixed with mucosal adjuvants we sought to induce anti-HIV memory-type immune responses in both the mucosal and systemic compartments. Prime/boost immunizations were performed through five IN immunizations alone with HIV-env oligomeric gp140 (Ogp140) or HIV-gag-p24 mixed with Escherichia coli heat labile-derived mutant adjuvants or two parenteral immunizations with DNA encoding HIV-env or -gag adsorbed to microparticles followed by three IN immunizations with p24 gag protein and the mutant adjuvants. Both modes of immunizations induced anti-gp140 plasma and vaginal IgG and IgA as well as interferon (IFN)-gamma secreting peripheral blood mononuclear cells (PBMC) after HIV-env and -gag peptide restimulation. After a resting period of 4 months, when the levels of humoral and cellular responses had decreased, intramuscular (IM) booster immunizations with p55-gag protein adsorbed to microparticles and Ogp140 in MF59 oil in water emulsion significantly enhanced anti-HIV plasma and vaginal antibody, as well as peripheral blood IFN-gamma responses in all groups of vaccinated macaques. Importantly, plasma neutralization activity against both homologous and heterologous HIV strains was observed in all groups following the IM booster immunizations with protein. These findings show that IN priming alone or combinations of parenteral and IN immunizations followed by IM booster immunizations hold promise to significantly enhance mucosal and systemic memory-type immune responses against HIV-1 antigens.