Women, HIV, and mucosal immunity

Interactions of the female hormonal environment, susceptibility to viral infections, and disease progression

Sex hormones influence susceptibility and disease predisposition for many genital tract infections. This review describes the mechanisms by which sex steroids affect mucosal immunity, with particular reference to human immunodeficiency virus (HIV) and genital herpes, and the stage-specific effects of hormonal contraception on human papillomavirus (HPV) infection. Estrogen's role is important in the early stages of several infections as it stimulates antibody- and cell-mediated immune responses. There is increased expression of some cytokines in peripheral blood and vaginal fluids during the follicular phase of the menstrual cycle and with use of hormonal contraception. Whether estrogen exerts a protective or deleterious influence depends on the infecting organism and stage of infection or disease. Estrogen apparently reduces susceptibility to primary HPV infection but in the event of persistent HPV infection, sex steroid hormones (estrogen and/or progesterone) are associated with progression to cervical cancer. It is important that these stage-specific effects are better described because most vaccines will try to prevent either infection or disease. Clinicians with patients at high risk of sexually transmitted infections, especially HIV, require better information on the risks associated with different hormonal contraceptive regimes.

Systemic and mucosal immune responses in mice after rectal and vaginal immunization with HIV-DNA vaccine

We examined the feasibility of inducing local and systemic human immunodeficiency virus (HIV)-specific immune responses by rectal and vaginal application of an HIV-DNA vaccine. Mice were immunized with an HIV-DNA vaccine preparation via a rectal or vaginal route. After several applications, HIV-specific antibodies were detected in sera, fecal extract solutions, and vaginal washes, and these antibodies were potent in inhibiting the syncytium formation of a CD4-positive human T cell line by a cell line capable of inducing HIV-1 infection. Spleen cells from rectally and vaginally immunized mice showed antigen-mediated IFN-gamma-inducing activity. In addition, with rectal immunization, mononuclear cells from both the spleen and the regional lymph nodes of the rectal region were found to be potent at inducing a cytotoxic T lymphocyte response. These humoral and cell-mediated immune responses were enhanced by augmenting the vaccine with granulocyte-macrophage colony-stimulating factor-expressing plasmids or IL-12-expressing plasmid. Our results demonstrated that both rectal and vaginal immunization could induce systemic and mucosal immunity and that these responses were enhanced by the addition of the above cytokine-expressing plasmids.

A Phase I safety and immunogenicity trial of UBI microparticulate monovalent HIV-1 MN oral peptide immunogen with parenteral boost in HIV-1 seronegative human subjects

Thirty-three HIV-seronegative adults were recruited into a Phase I safety and immunogenicity HIV-1 vaccine trial. The immunogens were as follows: a synthetic, monovalent, octameric HIV-1 MN V3 peptide in aluminum hydroxide (alum) adjuvant administered by intramuscular delivery; and a similar product encapsulated in biodegradable micro-spheres composed of co-polymers of lactic and glycolic acids, administered by the oral route. These were administered in three sequential oral doses, followed by a parenteral boost. No serious adverse experiences were observed. Oral administration of this vaccine, alone or in combination with parenteral boosting, resulted in no significant humoral, cellular, or mucosal immune responses.

Women and HIV--revisited ten years on

This article compares how women and their relationship to HIV has changed since the original publication of this article in 1990. The number of women infected with HIV has continued to rise, but, in contrast, there have been few changes in their management. We review transmission risks and manifestations of the infection, and also discuss the issues faced by women with HIV.

IgG subclass distribution in serum and various mucosal fluids of HIV type 1-infected subjects

We measured total IgG1, IgG2, IgG3, and IgG4 concentrations by ELISA in serum (S), total saliva (TS), cervicovaginal secretions (CVS), seminal secretions (SPE), and rectal secretions (RS) from either CDC II/III HIV-1-infected subjects or healthy volunteers. Human serum albumin was measured in parallel to calculate the relative coefficient of excretion (RCE). Levels of IgG1 and IgG3 directed against gp120 MN also were measured by ELISA in all samples, and the specific activity (SA) calculated. HIV-1-specific IgG2 and IgG4 were not compared, as total IgG2 and total IgG4 levels in HIV-1-infected subjects were found to be lower than in the healthy controls. Despite substantial interindividual variability, total IgG1 and IgG3 concentrations in all fluids were greater in the HIV-1-infected subjects than in the healthy controls. Calculations of RCE indicated predominantly a transudative origin for IgG subclasses in the different mucosal fluids, except for CVS, in which IgG1, IgG2, and IgG4 was produced locally. The transduction behavior of IgG3 in secretions appears to be different from that of other IgG subclasses. HIV-1-infected subjects were considered positive for IgG1 and IgG3 antibodies against gp120 MN if their antibody levels exceeded the maximum titer measured in the control group. Positive levels of anti-gp120 MN IgG1 were detected for 100% of HIV-1-infected individuals in S, CVS, and SPE, 97% in TS, and 75% in RS. Fewer subjects had positive levels of IgG3 to gp120 MN in their secretions (maximum 67% in CVS). Despite the low concentrations of total IgG3, mean SA values for IgG3 to gp120 MN were greater in secretions than in serum. No significant difference in the SA values for IgG1 to gp120 MN was observed between the different fluids. Only CVS had a local production of HIV-specific IgG1 Our results highlight the importance of an HIV-specific IgG1 and IgG3 immune response in mucosal fluids from HIV-1-infected subjects.

Rectal and vaginal immunization with a macromolecular multicomponent peptide vaccine candidate for HIV-1 infection induces HIV-specific protective immune responses

An effective vaccine for human immunodeficiency virus (HIV) is needed to stimulate the immune response of the genital mucus to prevent mucosal transmission of the virus. We have developed a macromolecular multicomponent peptide vaccine candidate, VC1. Both rectal and vaginal immunization of VC1 mixed with cholera toxin (CT) induced HIV-1-specific IgA antibody in mouse fecal extract solution and vaginal wash. These antibody productions were enhanced by the combination with IL-4 or GM-CSF expressing plasmids. Either fecal extract or vaginal wash solution from immunized mice inhibited production of HIV-1IIIB p24 protein. The mononuclear cells from spleen, intestinal lymph nodes, or Peyer's patches from VC1- and CT-immunized mice released IFN-gamma or IL-4, when these cells were co-cultured with VC1 antigen. In addition, the regional lymphoid cells from rectal and vaginal region of mice immunized with VC1 and CT also elicited a substantial level of HIV-1-specific cytotoxic T cell (CTL) response. This CTL response was enhanced by the addition of IL-12 expressing plasmid. Our results clearly demonstrated that both rectal and vaginal immunization could induce systemic and mucosal immunities specific for HIV-1.

Antibody responses to a mucosally delivered HIV-1 gp120-derived C4/V3 peptide

T1-SP10MN(A) is a synthetic peptide containing a T-helper (Th), cytotoxic T cell (CTL) and a B-cell epitope derived from the HIV-1 gp120 envelope protein. This peptide can elicit both systemic and mucosal antibody responses following nasal immunization in various species. In the present study, three different mucosal immunization strategies were performed in rabbits to determine which induced a more vigorous antibody response to T1-SP10MN(A). Nasal immunization followed by nasal boosting was found to be superior at inducing both serum IgG and vaginal secretory IgA (S-IgA) when compared to nasal followed by vaginal boosting. Conversely, vaginal priming followed by vaginal boosting elicited minimal serum IgG and vaginal S-IgA responses to T1-SP10MN(A), but moderate levels of vaginal IgG were detected. This study further demonstrates that vaginal immune responses can be elicited by immunization at distant and local mucosal sites.

Immunoglobulin concentrations and antigen-specific antibody levels in cervicovaginal lavages of rhesus macaques are influenced by the stage of the menstrual cycle

The levels of antigen-specific antibodies (Abs) and immunoglobulins in the cervical mucus of women vary with the menstrual cycle; the highest levels occur during menses, and the lowest occur during the periovulatory period. The rhesus macaque is a widely used animal model of female genital tract immunity. We sought to determine whether rhesus macaques have a cyclical pattern of changing cervicovaginal Ab and immunoglobulin levels that is similar to that of the human female. This study examined the relationship of the stages of the menstrual cycle to genital mucosal and systemic immunoglobulin concentrations and Ab levels in rhesus macaques. In all seven rhesus macaques studied, the immunoglobulins G and A and some antibodies in cervicovaginal lavages varied with the stages of the menstrual cycle, and in many cases this variation reached the level of statistical significance. In a pattern similar to that of women, the highest levels of Abs and immunoglobulins occurred during menses, and the lowest levels occurred around the time of ovulation. However, the Ab and immunoglobulin levels in serum and rectal lavages did not change with the menstrual cycle stage. The results of this study are consistent with the hypothesis that the ovarian hormones that drive the menstrual cycle influence genital tract immunity in female primates.

Comparison of the distribution of IgG and IgA antibodies in serum and various mucosal fluids of HIV type 1-infected subjects

We compared IgG and IgA distribution in serum, three different salivary samples, two different rectal secretion samples, cervicovaginal secretions, and seminal secretions from asymptomatic CDC stage II/III HIV-1-infected subjects (n = 44) and from HIV-1-seronegative volunteers (n = 52). In-house ELISAs were used to measure total IgG and total IgA levels, as well as HIV-specific anti-gp120 MN and anti-p24 LAI IgG and IgA. Human serum albumin was titrated in parallel to calculate the relative coefficient of excretion (RCE). In spite of substantial interindividual variability, total IgG concentrations in all fluids were found to be significantly greater in the HIV-1-infected group than in the seronegative subjects. Calculation of RCE values revealed three different types of mucosal secretion: secretions with no local Ig production, such as sperm; secretions with local production of IgA and transudative origin of IgG, such as salivary and rectal samples; and secretions with local production of both IgG and IgA, such as in cervicovaginal secretions. For all mucosal specimens from HIV-1-infected subjects, the response to HIV-1 was predominantly IgG, with highest titers observed in cervicovaginal secretions (although these were lower than serum levels). In contrast, the specific IgA response appeared weaker in the mucosa than in serum.

Assessment of mucosal immune response in genitourinary tract using urine

A novel method to assess mucosal immune response in the genitourinary mucosa after immunization with a mucosal vaccine has been developed. In this method, secretory IgA antibody is measured by a highly sensitive enzyme immunoassay (immune-complex transfer enzyme immunoassay) using urine as a specimen. The urinary IgA antibody response could be detected by the immune-complex transfer enzyme immunoassay. In contrast, a conventional enzyme immunoassay (enzyme-linked immunosorbent assay (ELISA)) could not detect this response because of its low sensitivity. Because urine samples can be collected easily and nontraumatically, not only from experimental animals but also from humans, both males and females, the present method may be applicable for assessing the protective efficacy of candidates for mucosal vaccines against sexually transmitted microorganisms, such as human immunodeficiency virus. Furthermore, the usefulness of this method for novel mucosal vaccine formulae was shown for a model in which vaccine antigen and Bordetella pertussis adjuvant were adsorbed onto CaCO, and enclosed in enteric coated capsules.

HIV-1 Neutralizing Antibodies in the Genital and Respiratory Tracts of Mice Intranasally Immunized with Oligomeric gp160

Because mucosal surfaces are a primary route of HIV-1 infection, we evaluated the mucosal immunogenicity of a candidate HIV-1 vaccine, oligomeric gp160 (o-gp160). In prior studies, parenteral immunization of rabbits with o-gp160 elicited broad neutralizing serum Ab responses against both T cell line-adapted HIV-1 and some primary HIV-1 isolates. In this study, nasal immunization of mice with o-gp160, formulated with liposomes containing monophosphoryl lipid A (MPL), MPL-AF, proteosomes, emulsomes, or proteosomes with emulsomes elicited strong gp160-specific IgG and IgA responses in serum as well as vaginal, lung, and intestinal washes and fecal pellets. The genital, respiratory, and intestinal Abs were determined to be locally produced. No mucosal immune responses were measurable when the immunogen was given s.c. Abs from sera and from vaginal and lung washes preferentially recognized native forms of monomeric gp120, suggesting no substantial loss in protein tertiary conformation after vaccine formulation and mucosal administration. Inhibition of HIV-1MN infection of H9 cells was found in sera from mice immunized intranasally with o-gp160 formulated with liposomes plus MPL, proteosomes, and proteosomes plus emulsomes. Formulations of o-gp160 with MPL-AF, proteosomes, emulsomes, or proteosomes plus emulsomes elicited HIV-1MN-neutralizing Ab in lung wash, and formulations with proteosomes, emulsomes, or proteosomes plus emulsomes elicited HIV-1MN-neutralizing Ab in vaginal wash. These data demonstrate the feasibility of inducing both systemic and mucosal HIV-1-neutralizing Ab by intranasal immunization with an oligomeric gp160 protein.

Attitudes about human immunodeficiency virus immunization: the influence of health beliefs and vaccine characteristics

BACKGROUND AND OBJECTIVES

The development of a vaccine to prevent human immunodeficiency virus (HIV) infection is a highly desirable goal. However, there may be a number of psychosocial barriers to HIV vaccine acceptance. The purpose of this study was to begin to examine some factors that might influence attitudes about HIV immunization.

GOAL

To evaluate the relationship of health beliefs and vaccine characteristics to acceptability of hypothetical HIV immunization.

STUDY DESIGN

The subjects were 222 college students who completed self-administered questionnaires that addressed health beliefs, vaccine characteristics, and acceptability of hypothetical HIV vaccines.

RESULTS

Health beliefs independently predictive of HIV vaccine acceptability included perceived susceptibility to HIV, perceived nonmembership in a traditionally defined acquired immune deficiency syndrome (AIDS) risk group, and fear of the vaccine causing AIDS. Of the vaccine characteristics, efficacy influenced vaccine acceptability most strongly, followed by type of vaccine.

CONCLUSION

These results suggest that universal HIV vaccine acceptance cannot be assumed and that vaccine characteristics and individuals' health beliefs are likely to influence decisions regarding HIV immunization.

Gynecology and family planning care for the woman infected with HIV

This article reviews the interactions between HIV infection and a variety of gynecologic conditions, including lower genital tract neoplasia, pelvic inflammatory disease, menstrual disorders, sexually transmitted diseases, and vaginitis. Important considerations in choosing a family planning method for women infected with HIV-infected women will respond to standard therapy, but require multiple courses of treatment or use of innovative treatment methods. All HIV-infected women deserve careful evaluation for and treatment of gynecologic diseases.

IgA immunity in HIV type 1-infected chimpanzees. II. Mucosal immunity

Vaginal wash fluids from chimpanzees cervically infected with HIV-1 and saliva from intravenously and cervically infected chimpanzees were analyzed for total IgA, IgA1, IgA2, IgG, and albumin concentrations and for reactivity against HIV-1. No overt abnormalities were detected in salivary immunoglobulin or albumin concentrations in either group of animals. Anti-HIV IgA and IgA subclass antibodies were demonstrated in saliva from five of six intravenously infected chimpanzees and in two of four cervically infected animals, with titers ranging from 1:5 to 1:20. HIV-specific IgG antibodies could be detected in saliva from half of the systemically infected group, the highest titer being 1:2560, whereas the highest anti-HIV IgG titer in the mucosally infected group was 1:20. Western blot analyses of the first saliva samples obtained after initial virus exposure revealed IgG, IgA, and IgA subclass antibodies directed at the env, gag, or pol gene products in both groups of chimpanzees. Examination of IgG, IgA, IgA1, and IgA2 concentrations in vaginal washes from cervically infected animals showed that IgG levels were highest, but IgA and IgA subclass reactivities against HIV-1 were more prominent than that of IgG. These results demonstrate that systemic infection of chimpanzees with HIV-1 elicits mucosal responses specific for HIV, and vaginal infection of chimpanzees induces a common mucosal immune response reminiscent of that in humans.

Toward a poliovirus-based simian immunodeficiency virus vaccine: correlation between genetic stability and immunogenicity

Recombinant polioviruses expressing foreign antigens may provide a convenient vaccine vector to engender mucosal immunity. Replication-competent chimeric viruses can be constructed by fusing foreign antigenic sequences to several positions within the poliovirus polyprotein. Artificial cleavage sites ensure appropriate proteolytic processing of the recombinant polyprotein, yielding mature and functional viral proteins. To study the effect of the position of insertion, two different recombinant polioviruses were examined. A small amino-terminus insertion delayed virus maturation and produced a thermosensitive particle. In contrast, insertion at the junction between the P1 and P2 regions yielded a chimeric poliovirus that replicated like the wild type. Eight different chimeras were constructed by inserting simian immunodeficiency virus (SIV) sequences at the P1/P2 junction. All recombinant viruses replicated with near-wild-type efficiency in tissue culture cells and expressed high levels of the SIV antigens. One of the inserted fragments corresponding to gp41 envelope protein was N-glycosylated but was not secreted. Inserted sequences were only partially retained after few rounds of replication in HeLa cells. This problem could be remedied to some extent by altering the sequences flanking the insertion point. Reducing the homology of the direct repeats by 37% decrease the propensity of the recombinant viruses to delete the insert. To determine the immunogenic potential of the recombinants, mice susceptible to poliovirus infection were inoculated intraperitoneally. The antibody titers elicited against Gag p17 depended on the viral doses and the number of inoculations. In addition, recombinants which display higher genetic stability were more effective in inducing an immune response against the SIV antigens, and inoculation with a mix of recombinants carrying different SIV antigens (a cocktail of recombinants) elicited humoral responses against each of the individual SIV sequences.

Mucosal immune response to an HIV C4/V3 peptide following nasal or intestinal immunization of rabbits

The HIV env-encoded synthetic peptide T1-SP10MN(A) contains immunodominant epitopes of the C4/V3 regions of gp120. The mucosal immunogenicity of this peptide in various vaccine preparations was first tested in rabbits using chronically isolated Thiry-Vella (T-V) ileal loops. Intestinal and serum samples collected from rabbits immunized via T-V loops demonstrated secretory IgA (S-IgA) and IgG anti-T1-SP10MN(A), respectively, when assayed by ELISA. Intranasal delivery of the peptide supplemented with cholera toxin (CT) resulted in serum IgG and S-IgA anti-T1-SP10MN(A) in vaginal and nasal secretions. This study further demonstrates the utility of rabbits as a convenient animal model for HIV vaccine research and the relationship between nasal immunization and vaginal immunity.

Salivary binding antibodies induced by human immunodeficiency virus type 1 recombinant gp120 vaccine. The NIAID AIDS Vaccine Evaluation Group

Salivary binding antibodies induced by candidate human immunodeficiency virus type 1 (HIV-1) vaccines in healthy, HIV-1 uninfected volunteers were assessed in a clinical trial evaluating intramuscularly injected HIV-1MN recombinant gp120 (rgp120) vaccine alone or with HIV-1IIIB rgp120 vaccine. The two rgp120 vaccines induced envelope glycoprotein-specific immunoglobulin G (IgG) and IgA antibodies in whole saliva and serum.

Cervical intra-epithelial neoplasia in women infected with human immunodeficiency virus

OBJECTIVE

To investigate the relationship between human immunodeficiency virus (HIV) and cervical intra-epithelial neoplasia (CIN).

DESIGN

A prospective study to determine the prevalence of cervical intra-epithelial neoplasia in 111 HIV-positive women.

METHODS

In total, 111 HIV + women were enrolled and underwent cervical biopsy and CD4 T-lymphocyte determination. Of the 111 women, 26 (23.4%) had CIN and another 26 (23.4%) had histologic evidence of cervicitis.

RESULTS

No significant difference was found between transmission group, CDC stage of disease, CD4 T-lymphocyte count and pregnancy. There was a significant association with concomitant human papillomavirus (HPV) infection (P < 0.001).

CONCLUSION

Public health measures are needed to provide Papanicolaou smear screening and appropriate clinical follow-up and treatment of women infected with the human immunodeficiency virus.

The impact of recent advances in microbiology and immunology on perinatal and women's health care

Microbiology and immunology have offered important advances in the care of women and newborns. Understanding of the interplay between individuals and the microorganisms associated with them has provided the framework for important changes in practice. An excellent historical example of this idea, well known to nurses, involves puerperal fever. A recent example is knowledge of the relationship of breastfeeding and human immunodeficiency virus. Recent advances in microbiology and immunology that have improved women's health include improved diagnostic tests and a more complete understanding of the vaginal biofilm.

Infection of vaginal and colonic epithelial cells by the human immunodeficiency virus type 1 is neutralized by antibodies raised against conserved epitopes in the envelope glycoprotein gp120

The rectal and genital tract mucosae are considered to be major sites of entry for the human immunodeficiency virus (HIV) during sexual contact. We now demonstrate that vaginal epithelial cells can be infected by HIV type 1 (HIV-1) via a mechanism similar to that described for neuroglial cells and, more recently, for colorectal epithelial cells, involving initial interaction of the HIV-1 envelope glycoprotein gp120 with a cell-surface glycosphingolipid (sulfated lactosylceramide). A hyperimmune serum against gp120 was able to neutralize HIV-1 infection of vaginal epithelial cells. Site-directed immunization was employed to identify sites on gp120 recognized by antibodies neutralizing HIV-1 infection of vaginal and colonic epithelial cells. Hyperimmune sera were raised in monkeys against a series of 40 overlapping synthetic peptides covering the entire sequence of HIV-1 (HTLV-IIIB) gp120. Antisera raised against five synthetic peptides, corresponding to three relatively conserved regions and to the hypervariable region (V3 loop), efficiently neutralized HIV-1 infection of human vaginal epithelial cells in vitro. Similar results were obtained with the colonic cells. Hyperimmune sera to all five peptides have been shown earlier to neutralize HIV-1 infectivity in CD4+ T cells. These results have obvious implications for the design of mucosal subunit vaccines against sexually transmitted HIV-1 infections.

Nucleolar organizer regions and cervical intraepithelial neoplasia among women with human immunodeficiency virus infection

OBJECTIVE

Our purpose was to evaluate the proliferative activity of cervical intraepithelial neoplasia lesions in human immunodeficiency virus-seropositive women.

STUDY DESIGN

The proliferative activity of cervical intraepithelial neoplasia lesions was measured by nucleolar organizer regions-associated proteins count. Twenty-two biopsy specimens of cervical intraepithelial neoplasia lesions from patients positive for human immunodeficiency virus were compared with 22 matched biopsy specimens obtained from controls negative for the virus.

RESULTS

The mean count of nucleolar organizer regions-associated proteins per cell was 9.5 +/- 3.7 (SD) in human immunodeficiency virus-positive patients and 7.6 +/- 2.8 in human immunodeficiency virus-negative controls (p < 0.0001 by Poisson test of heterogeneity of counts). The difference in counts between the two groups, which was confirmed by log-linear analysis, persisted within each severity stratum of cervical intraepithelial neoplasia and was independent of associated human papillomavirus infection. In human immunodeficiency virus-positive patients log-linear analysis showed that high-grade cervical intraepithelial neoplasia, the presence of human papillomavirus infection, and the severity of human immunodeficiency virus disease were independently correlated with increased nucleolar organizer regions-associated protein counts per cell.

CONCLUSION

The results of this study indicate that the proliferative activity of cervical intraepithelial neoplasia lesions of human immunodeficiency virus-positive patients was increased compared with matched lesions from human immunodeficiency virus-negative women. This finding suggests the possibility of an increased oncogenic progression of cervical intraepithelial neoplasia lesions in human immunodeficiency virus-positive patients.

In vitro HIV1 infection of human cervical tissue

Heterosexual intercourse is the major mode of transmission of the human immunodeficiency virus (HIV) worldwide. Heterosexual transmission of HIV is particularly important in Africa and is increasing in the developed world. The mechanism of HIV infection of the female genital tract with HIV and subsequent events leading to clinical infection are not fully understood. In particular, the primary cellular targets of HIV infection in the female genital tract have not been determined. We have established an in vitro model for studying HIV infection of the human adult cervix by HIV. Human cervical mucosal explants were briefly exposed to HIV strains of different tropism and maintained in organ culture for 7 days. HIV infection detected by immunohistochemistry and in situ hybridization was only observed in cervical explants exposed to macrophage tropic strain HIV1Ba-L. HIV-infected cells were located in submucosa and had the morphology and distribution of macrophages. While CD4+/CD3+ T cells were still present at day 7 in the organ culture tissue, no infection of cervical explants was seen with T cell tropic strains even in the presence of phytohaemagglutinin and IL2. This model system will enable study of the dynamics of HIV infection of the human cervix and analysis of possible prophylactic or therapeutic strategies.

Mucosal origin of AIDS

The natural history of AIDS implies sexual and breast-milk transmission of HIV across the mucosal lining of digestive and reproductive organs. Intraepithelial mucosal lymphocytes specialized in handling foods, air-borne, and microbial pathogens crossing the mucosal barrier represent up to 90% of immunocompetent cells in a human body. Enteropathy and respiratory infections, the main symptoms and cause of death in AIDS, are attributed to the failure of mucosal immunity.

A synoptic inventory of needs for research on women and tropical parasitic diseases. I. Application to urinary and intestinal schistosomiasis

The determinants of major parasitic infections in women have never been studied systematically. Much work remains to be done before vital gaps in our knowledge will be filled. The protocol presented here categorizes the determinants of parasitic diseases, and functions as an inventory for research needs and priorities. In this paper, the synoptic inventory is tested by matching it against the scientific knowledge of schistosomiasis that is at hand. Available data and existing lacunae are discussed. We conclude that the environmental, economic, socio-cultural, nutritional, genetic, biological and immunological factors which determine schistosomiasis in women are largely unknown. There is an urgent need for systematic and interdisciplinary investigations before appropriate and sustainable interventions can be initiated.

T- and B-cell functions and epitope expression in nonhuman primates immunized with simian immunodeficiency virus antigen by the rectal route

Transmission of human immunodeficiency virus (HIV) in North America and Europe occurs most commonly through the rectal mucosa during homosexual intercourse. The simian immunodeficiency virus (SIV) macaque model has been used to investigate rectal immunization. The vaccine used was a recombinant SIV gag p27 expressed as hybrid Ty virus-like particles (Ty-VLP). Sequential ororectal (OR) mucosal immunization was compared with i.m. immunization. Whereas both routes of immunization induced serum IgA and IgG p27 antibodies, only OR immunization induced rectal secretory IgA antibodies. Specific CD4+ T-cell proliferative responses to stimulation with p27 were found after i.m. immunization only in the blood and spleen, but after OR immunization they were found in the internal iliac and inferior mesenteric lymph nodes in addition to the blood and spleen. T-cell epitope mapping of the proliferative responses of short-term cell lines (STCLs) grown from peripheral blood or lymphoid cells revealed a major epitope within the polypeptide 121-150 after either route of immunization. Two minor T-cell epitopes were found within peptide 41-80 in STCLs from splenic and circulating cells. B-cell epitope mapping of serum or biliary IgA and IgG antibodies revealed two overlapping or adjacent immunodominant epitopes to the T-cell epitopes within the polypeptides 121-170 and 51-90. The results suggest that rectal augmented by oral immunization with a recombinant particulate antigen in nonhuman primates elicits secretory IgA and to a lesser extent IgG responses in the draining lymph nodes and the rectal mucosa, whereas systemic immunization targets predominantly splenic and circulating T- and B-cell responses. These findings may have important implications in the strategy of designing vaccines in prevention of homosexual transmission of HIV infection.

Human immunodeficiency virus infection in pregnancy

Human immunodeficiency virus (HIV) infection in women is an increasing problem. World wide, at least 25% of all infections occur in adolescent or adult women, most of whom are of child-bearing age. The commonest modes of acquisition of HIV infection are sexual contact with an HIV-infected male and sharing needles during injecting drug use. Vertical transmission is the major route of HIV infection in infants and children and can occur in utero, intrapartum, through exposure to infected blood or secretions, or post partum, via breast milk. HIV infection has not been demonstrated to affect fertility, or to influence the outcome of pregnancy unless there is evidence of significant immune dysfunction, with CD4 counts below 400/mm3. Though data are limited, pregnancy does not appear to affect the course of HIV infection. Low CD4 counts predispose women to the opportunistic infectious complications of HIV. Pathogens include Candida sp., Mycobacterium tuberculosis, Pneumocystis carinii, Toxoplasma gondii, Cryptococcus neoformans and Cryptosporidium. These pathogens require early recognition and diagnosis if optimal treatment and outcome are to be attained. Treatment with zidovudine and prophylaxis against Pneumocystis carinii are appropriate when CD4 counts are less than 200/mm3, though the safety of zidovudine in early pregnancy is not known. Similarly it is not known whether zidovudine treatment of the mother prevents transmission of HIV infection to her baby. Caesarean section does not prevent peripartum transmission of HIV and should be undertaken only for other appropriate indications. The utility of antenatal screening for HIV depends upon the seroprevalence in the population. Such programmes must be supported by comprehensive clinical care as well as sensitive and non-judgemental counselling.

The prevalence of human retroviral infections in female patients attending a central London sexually transmitted disease clinic: 1985-1990

OBJECTIVES

To determine the prevalence of infection with HIV-1, HIV2, HTLV-1 and HTLV-2 in female attenders at a central London sexually transmitted disease clinic in an 8 week period in 1989-1990, and compare it with similar samples studied between 1985 and 1987.

DESIGN

Anonymous testing of serum samples from consecutive female patients having routine serological investigation for syphilis. Testing was for clinically important retroviruses, Hepatitis B core antibodies (anti-HBc), and p24 and reverse transcriptase (RT) antigens. Age (in 5 year bands), nationality (in broad geographical zones), diagnosis on the day of presentation, and history of intravenous drug usage were recorded for each patient. Annual gonorrhoea rates were analysed from 1981 to 1990.

SETTING

Outpatients of the department of genitourinary medicine.

PATIENTS

A total of 850 females attending consecutively and having routine syphilis serology.

MAIN RESULTS

The prevalence of anti-HIV-1 in female attenders in 1989-1990 was 0.35% (3/850). Prevalence in the same clinic has remained statistically unchanged since the first female cases were identified in 1986. No cases of HIV-2, HTLV-1 or HTLV-2 were identified, and no early HIV-1 infection evidenced by the presence of p24 or RT antigenaemia was found. Female gonorrhoea rates continued to decline but other STD monthly/annual rates have remained unchanged.

CONCLUSIONS

Over the last 5 years prevalence of HIV-1 infection in females in our clinic has remained unchanged and other retroviral infections have remained absent. However, the unaltered rates of other genital infections, their potential role in the heterosexual spread of HIV-1 infection, and the lack of evidence for any major changes in female sexual behaviour suggests there is a need to remain vigilant. This work complements the MRC multicentre, unlinked, genitourinary medicine clinic, anonymous testing programme, and our group will continue to apply this simple methodology to specimens from female attenders to contribute to the surveillance of the evolving HIV-1 epidemic.

Expression and gene transcript of Fc receptors for IgG, HLA class II antigens and Langerhans cells in human cervico-vaginal epithelium

The mechanism of transmission of HIV from the male to the female genital tract or in the reverse order is not clear. CD4 glycoprotein is the receptor for HIV and Langerhans cells and the related dendritic cells could play a role in the initial transmission of HIV. Fc receptors (FcR) for IgG might be involved in antibody-mediated binding of HIV. We carried out an immunohistological study of normal human cervical and vaginal epithelia for the presence of CD4 glycoprotein, Langerhans cells and FcR to IgG. CD4+ glycoprotein was not found in the vaginal or cervical epithelium, with the exception of a few endocervical epithelial cells. A small number of CD4+ mononuclear cells were found in the endocervical epithelium of a third of the specimens but a large number of CD4+ cells was found in the submucosa of most of the cervical and vaginal specimens. Langerhans cells expressing CD4, HLA class II, Fc gamma R2 and Fc gamma R3 were detected in most vaginal, ectocervical and transformation zone epithelia and in 9/14 endocervical tissues. Fc gamma R3 was detected in about two-thirds of the columnar endocervical epithelium and the transformation zone. A smaller number of specimens expressed Fc gamma R2 in these epithelia, but Fc gamma R1 was not detected. We then demonstrated mRNA for Fc gamma R3 in the columnar endocervical epithelial cells and transformation zone by in situ hybridization, using a CD16-RNA probe. Fc gamma R3 and Fc gamma R2 gene transcripts were also found in fetal cervical tissue by applying the polymerase chain reaction to amplify portions of the Fc gamma R3 and Fc gamma R2 coding sequences in cDNA prepared from fetal RNA. HLA-DR was found in the endocervical cells, transformation zone and in Langerhans cells of all specimens. The presence of Langerhans cells, Fc gamma receptors and HLA class II antigen offers three potential mechanisms for cervico-vaginal HIV transmission: (i) direct HIV infection of Langerhans cells, (ii) binding of HIV antibody complexes to cervical epithelial Fc gamma receptors and (iii) binding of HIV infected CD4+ cells to cervical HLA class II antigen which may infect these or the adjacent CD4+ cells.

Boosted mucosal immune responsiveness in the rat intestine by actively transported hexose

Anaphylaxis-mediated intestinal fluid secretion was measured in Trichinella spiralis- or ovalbumin-immunized rats challenged intraduodenally with T. spiralis somatic antigen (1 mg protein/0.5 mL saline) or ovalbumin (1 mg/0.5 mL saline), respectively. Intestinal fluid volume was measured 30 minutes after challenge as an index of net secretion. Challenge with the antigenic bolus containing 40 mmol/L D-glucose induced twice the fluid secretion as that induced by either antigen alone. L-Glucose was an ineffective substitute for D-glucose. The enhancement of secretion by D-glucose was dependent on prior immunologic sensitization, was diminished in the presence of phlorizin, and was mimicked by beta-methyl glucoside. Results indicate that the active transport of D-glucose augments the antigen-mediated fluid secretion, possibly by enhancing permeation of the intestinal epithelium to antigen, thereby providing greater access to the mucosal immune system.

Association between HIV1 infection and sexually transmitted disease among men in Central Africa

In Africa, heterosexual contact is the major route of transmission of the human immunodeficiency virus (HIV). Previous studies have strongly suggested that other sexually transmitted diseases (STD) may facilitate HIV transmission. However, the association of HIV infection with other STD may simply be a marker of sexual promiscuity. Thus, we compared the association of different STD, HIV status, and sexual behaviour of 160 STD patients and 95 STD-free control individuals. Results showed that STD patients differed from controls in most of the sociological and behavioural parameters, as well as in HIV serological status. Within the STD group, people with genital ulcer disease (GUD) (n = 62) were more likely to be HIV-seropositive (21%) than people with urethritis (n = 98, 11.2%). Meanwhile, there was almost no difference in the sociological and behavioural parameters between the GUD and the urethritis group. Thus, our results reinforce the specific role of mucosal breakage (i.e. genital ulcers) in the transmission of HIV.

Prospects for human mucosal vaccines

The selective induction of antibodies in external secretions and mucosal T cell-mediated immunity are desirable for the prevention of various systemic as well as predominantly mucosa-restricted infections. An enormous surface area of mucosal membranes is protected primarily by antibodies that belong, in many species, to the IgA isotype. Such antibodies are produced locally by large numbers of IgA-containing plasma cells distributed in subepithelial spaces of mucosal membranes and in the stroma of secretory glands. In humans and in some animal species, plasma-derived IgA antibodies do not enter external secretions in significant quantities and systemically administered preformed IgA antibodies would be of little use for passive immunization. Systemic administration of microbial antigens may boost an effective S-IgA immune response only in a situation whereby an immunized individual had previously encountered the same antigen by the mucosal route. Immunization routes that involve ingestion or possibly inhalation of antigens lead to the induction of not only local but also generalized immune responses, manifested by the parallel appearance of S-IgA antibodies to ingested or inhaled antigens in secretions of glands distant from the site of immunization. Convincing evidence is available that antigen-sensitized and IgA-committed precursors of plasma cells and T cells from IgA inductive sites (e.g., BALT, GALT, and tonsils) are disseminated to the gut, other mucosa-associated tissues, and exocrine glands. However, due to the limited absorption of desired antigens from the gut lumen of orally immunized individuals, repeated large doses of antigens are required for an effective S-IgA response. Novel antigen delivery systems for the stimulation of such responses has been briefly reviewed here. These, of course, include genetically engineered bacteria and viruses, CT/CFB, liposomes and microspheres. Live attenuated or genetically manipulated bacteria expressing other microbial antigens have been used for selective colonization of GALT. Unique antigen packaging and the use of adjuvants suitable for oral administration hold promise for an efficient antigen delivery to critical tissues in the intestine and deserve extensive exploration. The oral immunization route appears to have many advantages over systemic immunization; however, one must consider alternate IgA inductive sites and compartmentalization within the Common Mucosal Immune System. In addition to providing immunity on mucosal surfaces, which are the most common sites of entry of infectious agents, the mucosal routes of administration are more acceptable and do not require stringent criteria applicable for injectable vaccines, storage problems may be simplified, and large populations of individuals can be immunized simultaneously without the assistance of highly trained health personnel.

Impediments, imponderables and alternatives in the attempt to develop an effective vaccine against AIDS

A personal view is presented that current successful vaccines against 'ordinary' viruses do not provide the guidelines needed for development of effective vaccines against the 'extraordinary' viruses that cause AIDS. Present 'candidate' AIDS vaccines fail to recognize the special attributes that are needed to make them successful. There is an urgent need for intensive studies of pathogenesis to seek and find the clues needed for vaccine attack that are at present unknown. Also needed is a targeted Research and Development organization comprising a cadre of capable scientists of requisite disciplines in adequate facilities, dedicated solely to the development of a vaccine against AIDS. The urgency imposed by the AIDS pandemic merits a new dedication to targeted basic research discovery and an effectively concentrated and coordinated applied research initiative.