Decreased helper T lymphocytes in homosexual men. II. Sexual practices

Differential Immunodominance Hierarchy of CD8+ T-Cell Responses in HLA-B*27:05- and -B*27:02-Mediated Control of HIV-1 Infection

The well-characterized association between HLA-B*27:05 and protection against HIV disease progression has been linked to immunodominant HLA-B*27:05-restricted CD8+ T-cell responses toward the conserved Gag KK10 (residues 263 to 272) and polymerase (Pol) KY9 (residues 901 to 909) epitopes. We studied the impact of the 3 amino acid differences between HLA-B*27:05 and the closely related HLA-B*27:02 on the HIV-specific CD8+ T-cell response hierarchy and on immune control of HIV. Genetic epidemiological data indicate that both HLA-B*27:02 and HLA-B*27:05 are associated with slower disease progression and lower viral loads. The effect of HLA-B*27:02 appeared to be consistently stronger than that of HLA-B*27:05. In contrast to HLA-B*27:05, the immunodominant HIV-specific HLA-B*27:02-restricted CD8+ T-cell response is to a Nef epitope (residues 142 to 150 [VW9]), with Pol KY9 subdominant and Gag KK10 further subdominant. This selection was driven by structural differences in the F pocket, mediated by a polymorphism between these two HLA alleles at position 81. Analysis of autologous virus sequences showed that in HLA-B*27:02-positive subjects, all three of these CD8+ T-cell responses impose selection pressure on the virus, whereas in HLA-B*27:05-positive subjects, there is no Nef VW9-mediated selection pressure. These studies demonstrate that HLA-B*27:02 mediates protection against HIV disease progression that is at least as strong as or stronger than that mediated by HLA-B*27:05. In combination with the protective Gag KK10 and Pol KY9 CD8+ T-cell responses that dominate HIV-specific CD8+ T-cell activity in HLA-B*27:05-positive subjects, a Nef VW9-specific response is additionally present and immunodominant in HLA-B*27:02-positive subjects, mediated through a polymorphism at residue 81 in the F pocket, that contributes to selection pressure against HIV.IMPORTANCE CD8+ T cells play a central role in successful control of HIV infection and have the potential also to mediate the eradication of viral reservoirs of infection. The principal means by which protective HLA class I molecules, such as HLA-B*27:05 and HLA-B*57:01, slow HIV disease progression is believed to be via the particular HIV-specific CD8+ T cell responses restricted by those alleles. We focus here on HLA-B*27:05, one of the best-characterized protective HLA molecules, and the closely related HLA-B*27:02, which differs by only 3 amino acids and which has not been well studied in relation to control of HIV infection. We show that HLA-B*27:02 is also protective against HIV disease progression, but the CD8+ T-cell immunodominance hierarchy of HLA-B*27:02 differs strikingly from that of HLA-B*27:05. These findings indicate that the immunodominant HLA-B*27:02-restricted Nef response adds to protection mediated by the Gag and Pol specificities that dominate anti-HIV CD8+ T-cell activity in HLA-B*27:05-positive subjects.

Anal microbiota profiles in HIV-positive and HIV-negative MSM

OBJECTIVE

Because differences in anal microbial populations (microbiota) could affect acquisition of HIV or other conditions, especially among MSM, we profiled the microbiota of the anal canal, assessed its stability, and investigated associations with diversity and composition.

DESIGN

Microbiota profiles in anal swabs collected from 76 MSM (52 in 1989, swab-1; 66 1-5 years later, swab-2) were compared by HIV status (25 HIV-positive), T-cell subsets, and questionnaire data.

METHODS

Bacterial 16S rRNA genes were amplified, sequenced (Illumina MiSeq), and clustered into species-level operational taxonomic units (QIIME and Greengenes). Regression models and Wilcoxon tests were used for associations with alpha diversity (unique operational taxonomic units, Shannon's index). Composition was compared by Adonis (QIIME).

RESULTS

Most anal bacteria were Firmicutes (mean 60.6%, range 21.1-91.1%) or Bacteroidetes (29.4%, 4.1-70.8%). Alpha diversity did not change between the two swabs (N = 42 pairs). In swab-2, HIV-positives had lower alpha diversity (P ≤ 0.04) and altered composition, with fewer Firmicutes and more Fusobacteria taxa (P ≤ 0.03), not completely attributable to very low CD4(+) cell count (median 232 cells/μl), prior AIDS clinical diagnosis (N = 17), or trimethoprim-sulfamethoxazole use (N = 6). Similar but weaker differences were observed in swab-1 (HIV-positive median 580 CD4(+) cells/μl; no trimethoprim-sulfamethoxazole). Associations with T-cell subsets, smoking, and sexual practices were null or inconsistent.

CONCLUSIONS

The anal microbiota of MSM was relatively stable over 1-5 years. However, with uncontrolled, advanced HIV infection, the microbiota had altered composition and reduced diversity partially attributable to antibiotics. Investigations of microbial community associations with other immune perturbations and clinical abnormalities are needed.

Greater risk for HIV infection of black men who have sex with men: a critical literature review

HIV rates are disproportionately higher for Black men who have sex with men (MSM) than for other MSM. We reviewed the literature to examine 12 hypotheses that might explain this disparity. We found that high rates of HIV infection for Black MSM were partly attributable to a high prevalence of sexually transmitted diseases that facilitate HIV transmission and to undetected or late diagnosis of HIV infection; they were not attributable to a higher frequency of risky sexual behavior, nongay identity, or sexual nondisclosure, or to reported use of alcohol or illicit substances. Evidence was insufficient to evaluate the remaining hypotheses.Future studies must address these hypotheses to provide additional explanations for the greater prevalence of HIV infection among Black MSM.

Distribution of chemokine receptor CCR2 and CCR5 genotypes and their relative contribution to human immunodeficiency virus type 1 (HIV-1) seroconversion, early HIV-1 RNA concentration in plasma, and later disease progression

At the CC (beta) chemokine receptor 2 (CCR2) and CCR5 loci, combinations of common single-nucleotide polymorphisms (SNPs) and a 32-bp deletion (Delta32) form nine stable haplotypes (designated A through G*2). The distribution of these CCR2-CCR5 haplotypes was examined among 703 participants in the Multicenter AIDS Cohort Study (MACS), the District of Columbia Gay (DCG) Study, and the San Francisco Men's Health Study (SFMHS). Highly exposed and persistently seronegative (HEPS; n = 90) Caucasian men from MACS more frequently carried heterozygous G*2 (Delta32) genotypes (especially A/G*2) and less frequently carried the homozygous E/E genotype compared with 469 Caucasian seroconverters (SCs) from the same cohort (P = 0.004 to 0.042). Among 341 MACS Caucasian SCs with 6- to 12-month human immunodeficiency virus type 1 (HIV-1) seroconversion intervals and no potent antiretroviral therapy, mean plasma HIV-1 RNA level during the initial 42 months after seroconversion was higher in carriers of the E/E genotype and lower in those with the 64I-bearing haplotype F*2 or the Delta32-bearing haplotype G*2 (and especially genotypes A/G*2 and F*2/G*2). A multivariable model containing these CCR markers showed significant composite effects on HIV-1 RNA at each of four postconversion intervals (P = 0.0004 to 0.050). In other models using time to AIDS as the endpoint, the same markers showed more modest contributions (P = 0.08 to 0.24) to differential outcome during 11.5 years of follow-up. Broadly consistent findings in the larger MACS Caucasian SCs and the smaller groups of MACS African-American SCs and the DCG and SFMHS Caucasian SCs indicate that specific CCR2-CCR5 haplotypes or genotypes mediate initial acquisition of HIV-1 infection, early host-virus equilibration, and subsequent pathogenesis.

Diagnosis and treatment of sexually acquired proctitis and proctocolitis: an update

Sexually transmitted gastrointestinal syndromes include proctitis, proctocolitis, and enteritis. These syndromes can be caused by one or multiple pathogens. Routes of sexual transmission and acquisition include unprotected anal intercourse and oral-fecal contact. Evaluation should include appropriate diagnostic procedures such as anoscopy or sigmoidoscopy, stool examination, and culture. When laboratory diagnostic capabilities are sufficient, treatment should be based on specific diagnosis. Empirical therapy for acute proctitis in persons who have recently practiced receptive anal intercourse should be chosen to treat Neisseria gonorrhoeae and Chlamydia trachomatis infections. In individuals infected with human immunodeficiency virus (HIV), other infections that are not usually sexually acquired may occur, and recurrent herpes simplex virus infections are common. The approach to gastrointestinal syndromes among HIV-infected patients, therefore, can be more comprehensive and will not be discussed in this article.

Group sex in gay men: its meaning and HIV prevention implications

HIV/AIDS continues to pose a serious health hazard for gay men. Large numbers of men continue to become HIV infected each year, despite access to knowledge concerning how HIV is transmitted. Although gay men changed their sexual practices early in the epidemic, there is growing concern that there is a resurgence of risky sexual activities occurring in this group. Of particular concern is the resurgence of group sex activities. The purpose of this study was to explore the experiences of group sex in gay men to gain insight into the meaning of group sex to these men, the context in which it occurs, and men's views of how group sexual encounters relate to HIV transmission. The study used a qualitative approach to data collection. Ten self-identified gay men who reported engaging in group sex activities were interviewed concerning their experiences. Men reported that the most likely place for them to engage in group sex activities was in sex clubs, and a majority of their discussions centered on these clubs. Study data were analyzed using content analysis. Two overall categories of responses emerged from men's descriptions of their group sex experience: sexual desire and HIV/STD risk behaviors. Four themes--access to sex, sexual excitement or stimulation, sexual options, and control and sexual freedom--comprised the category of Sexual Desire. The themes identified within the category of HIV/STD risk behaviors included reframing risk, rejection of safer sex, and alcohol and drug use. The findings of the study suggest that sex in group settings such as sex clubs is a reality that must be addressed by HIV prevention efforts. Additionally, results indicate that current HIV prevention messages are being rejected by many gay men and need to be reevaluated for relevance two decades into the HIV/AIDS epidemic.

Dave Byar's contribution to epidemiology

Some of Dave Byar's personal qualities and his scientific approach are described. His work on substantive epidemiologic projects is mentioned briefly. There follows a review of his work on theoretical issues, including extentions of the Mantel-Haenszel procedure and other contingency table methods, confounding, and estimation of attributable and absolute risk from case-control data.

Effect of sexual practices on T cell subsets and delayed hypersensitivity in transsexuals and female sex workers

To determine whether ano-receptive unprotected sexual intercourse (SI) practised by transsexuals produces immunological abnormalities we compared delayed hypersensitivity skin tests (DTH) and T cell helper (CD4) and suppressor (CD8) subsets in 57 transsexuals and 69 female sex worker controls. The populations were matched for age, duration of prostitution, number of clients and previous use of antibiotics. Heterosexual males and females and transsexuals who practised protected SI, were also included as controls. All were HIV negative. There were significantly increased absolute CD4 and CD8 counts and decreased DTH and CD4/CD8 ratios in those who practised unprotected ano-receptive SI. These changes were unlikely to be due to any of the microbial agents tested. We conclude that ano-receptive sexual intercourse results in increased immunological abnormalities in these sex workers possibly as a result of rectal exposure to seminal alloantigens. These abnormalities could play an important role as co-factors in disease transmission.

Prognostic markers for AIDS

Human immunodeficiency virus (HIV) infection causes a number of clinical syndromes and many laboratory abnormalities, often heralding the development of the life-threatening opportunistic infections or malignancies that are known as the acquired immunodeficiency syndrome (AIDS). Drawing heavily on the results of prospective cohort studies, particularly those that my colleagues at the National Cancer Institute and I have conducted, this paper reviews the relationship of AIDS to clinical signs and symptoms, immunologic measures, and viral assays. The risk of AIDS in the next 3 years is at least 25 to 50% for HIV-infected subjects who have oral candidiasis, unexplained fever, unexplained weight loss, a CD4+ lymphocyte count below 200 cells/microliter, or combinations of these. Elevated serum levels of beta 2 microglobulin and neopterin also appear to be strong predictive markers of AIDS, but further work is needed in diverse HIV-infected populations, such as intravenous drug users and persons in pattern II countries, such as Haiti and central Africa. Elevated levels of interferon or HIV-p24 antigen in the serum are insensitive but highly specific AIDS markers that may have predictive value independent of CD4 lymphocyte levels. Several potentially valuable immunologic (immunoglobulin levels, tumor necrosis factor, soluble interleukin 2) and virologic (HIV viremia) assays remain to be thoroughly evaluated or technically simplified. Data from prospective cohort studies have provided clinical and laboratory markers of AIDS risk that have proved essential for therapeutic trials and other clinical decisions. As effective treatments for HIV infection and its complications begin to emerge, these marker data will also prove invaluable for mathematic modeling of the scope, course, and public health response to the epidemic.

Interaction of human immunodeficiency and papilloma viruses: association with anal epithelial abnormality in homosexual men

During the 7th annual follow-up of our cohort of homosexual men in 1989, we tested the hypotheses that infection with human immunodeficiency virus (HIV) may enhance the expression of human papilloma virus (HPV) and that the development of anal epithelial abnormality is related to a biologic interaction between these two viruses. Overall, 41 (39%) of the 105 men had anal swabs positive for one or more genotypes of HPV 6/11, 16/18 or 31/33/35. Twenty-three (53%) of the 43 HIV-positive subjects harbored HPV compared to 18 (29%) of the 64 HIV-negative subjects (p = 0.012), including higher prevalence rates for HPV genotypes 16/18 (p = 0.01), 6/11 (p = 0.007), and 31/33/35 (p = 0.07). Multivariate logistic regression analysis of the HIV-positive subjects showed low CD4+ cell counts to be an independent risk factor for detection of HPV (p = 0.04) and in particular for HPV genotypes 31/33/35 (p = 0.02) and 6/11 (p = 0.07). In contrast, similar analysis of the HIV-negative subset showed that a positive antibody test for syphilis was associated with HPV (p = 0.03). Anal epithelial abnormalities were found in 13 (14%) of 92 technically adequate cytologic smears and were strongly associated with detection of any HPV genotypes by the dot-blot method (p = 0.01), and in particular with HPV genotypes 6/11 (p = 0.001). None of 15 subjects with HPV detected only by PCR had anal epithelial abnormality. We propose a viral interaction model, in which HIV-related immune deficiency allows reactivation of HPV, with a subsequent or concomitant appearance of epithelial abnormality.

Urinary neopterin concentrations and T-cell subset data in HIV-1 infection

We investigated the ability of urinary neopterin concentrations and T-cell subset data, and their ratios to discriminate between anti-HIV-1 seronegatives, seropositives, and AIDS cases. Using receiver-operated-characteristics curves, neopterin levels were shown to provide the best discrimination. Of the ratios derived from the single variables, neopterin per CD4+ cell counts and neopterin per CD4+/CD8+ cell ratio were superior to the CD4+/CD8+ cell ratio. Multivariate analyses were performed using a generalized likelihood ratio approach as well as linear discriminant analysis. The combination of neopterin concentration and CD4+ T-cell count is well suited to discriminate between various stages of HIV-1 infection and, therefore, we recommend using more than one assay to evaluate disease progression.

Factors distinguishing homosexual males practicing risky and safer sex

A longitudinal study of patterns of sexual behavior among asymptomatic, homosexual males in New York City was conducted. Participants were interviewed at two time points, 6 months apart. Based on their reports of sexual behavior during a recent 'typical' month, respondents were classified at each time point as engaging in safer (or low-risk) sexual practices versus high-risk sexual behaviors. Discriminant analysis was employed to distinguish the 53 males classified as risky at both time 1 and time 2 from the 47 males classified as safer in both periods. Statistically significant discrimination was achieved with 10 psychosocial predictor variables, four of which were significant while controlling for all other variables in the model. Of these predictors, drug use within sexual contexts was particularly noteworthy, since it provided the greatest relative contribution to the discriminant function and appears to be an important candidate for educational intervention. Other significant variables included perceived adequacy of emotional support, number of years engaged in regular sexual intercourse with other males, and perceived difficulty in modifying sexual behavior. Self-esteem and alcohol consumption approached significance.

Risk factors for A.I.D.S. among homosexual men in France

To identify risk factors for A.I.D.S. among homosexual men in France, a high-risk group in a moderate-incidence area, we undertook a case-control study in Paris and its suburbs. Fifty-three cases were compared to 99 controls from a venereal disease clinic and 79 controls from the staff of an amateur gay broadcasting station. In our univariate analysis, cases were more likely than controls to belong to upper socio-economical classes, to have used local corticosteroids, to have regularly inhaled nitrites, to report history of syphilis and of herpes infections, to have higher level of promiscuity with occasional partners ("one night stands"), and to have had sexual encounters in the U.S.A. In the multivariate analysis, history of syphilis and promiscuity with occasional partners appeared to be the main risk factors, as well as the use of local corticosteroids, especially during the prodrome period. The correlation between promiscuity and disease risk was weak in our study when we did not discriminate between occasional and regular sex partners, contrary to that found in epidemiological studies of A.I.D.S. and H.I.V.-seropositivity in high-incidence areas. In association with the history of syphilis, the development of the syndrome in our moderate-incidence country is more correlated to the contact with "one-night-stand" partners rather than to the total number of the sex partners. The public health policies in our area should be adapted to these findings. Otherwise they may be less efficient than hoped.

Behavioral risk factors for HIV infection among homosexual men at a Boston community health center

Social and behavioral factors associated with human immunodeficiency virus (HIV) infection were analyzed using cross-sectional data from homosexual and bisexual male clients of a Boston community health center. Partners from California, and a previous period of greater sexual activity (a "high period"), were independently associated with positive HIV antibody status, as were the frequency of receptive anogenital contact, both during the "high period" and during the last six months.

What is safe sex? Suggested standards linked to testing for human immunodeficiency virus

Because of the lethality of the HIV epidemic, rational and scientifically defined standards of sex that preclude the spread of sexually transmitted diseases are required. In the context of an HIV-antibody test that has been documented to be extremely sensitive and specific, standards for truly safe sex can be defined. HIV testing can be used as a powerful tool for defining a series of standards for sexual partners that eliminates, with reasonable certainty, the further spread of HIV. Such standards provide a defined benchmark for future research aimed at evaluating the effectiveness of public health measures in arresting the spread of the virus. The fact that at least 10 million American blood donors and some 2 million Americans applying for or in the armed forces have been tested demonstrates that the adverse consequences of testing can be limited. Now is the time to minimize the fear and eliminate the risk of transmitting HIV to loved ones by urging widespread voluntary testing of sexually active adults and by developing standards for safe sex.

The genesis of fear: AIDS and the public's response to science

The AIDS (acquired immunodeficiency syndrome) crisis has aroused scientists to major research efforts and the public at times to near-hysteria. The media and their audience eagerly await the latest scientific reports, yet the public seems to respond selectively, embracing the most frightening interpretation of the data and discounting attempts to place those data in perspective. One might be tempted to conclude that questions of public health policy are best dealt with by expert judgment unsullied by lay opinion. Yet such an attitude supposes scientists to be governed by pure reason and to be beyond influence by narrow self-interest or by political or moralistic considerations, a self-serving assumption belied by an examination of the record. The erosion of public confidence in science has indeed bedeviled health authorities in their efforts to generate consensus on the policies they wish to implement, but the public response—including the response of scientists to AIDS—is a far more complex phenomenon.

Transmission of human immunodeficiency virus (HIV/HTLV-III/LAV): a review

The literature on the transmission of human immunodeficiency virus (HIV/HTLV-III/LAV) is reviewed. HIV spreads by vertical transmission and by iatrogenic transmission (transfer of blood or blood-containing products), by infected needles among i.v. drug users and, more rarely, among health care workers, but mainly by sexual contact. In Western countries the virus is mainly spread by passive anal intercourse among homosexuals and seldom by heterosexual intercourse. In African countries, however, the virus is mainly spread by heterosexual intercourse, probably because of other, concurring sexually transmitted diseases. Some preventive measures are discussed.

Three-year incidence of AIDS in five cohorts of HTLV-III-infected risk group members

The incidence of the acquired immune deficiency syndrome (AIDS) among persons infected with human T-lymphotropic virus type III (HTLV-III) was evaluated prospectively among 725 persons who were at high risk of AIDS and had enrolled before October 1982 in cohort studies of homosexual men, parenteral drug users, and hemophiliacs. A total of 276 (38.1 percent) of the subjects were either HTLV-III seropositive at enrollment or developed HTLV-III antibodies subsequently. AIDS had developed in 28 (10.1 percent) of the seropositive subjects before August 1985. By actuarial survival calculations, the 3-year incidence of AIDS among all HTLV-III seropositive subjects was 34.2 percent in the cohort of homosexual men in Manhattan, New York, and 14.9 percent (range 8.0 to 17.2 percent) in the four other cohorts. Out of 117 subjects followed for a mean of 31 months after documented seroconversion, five (all hemophiliacs) developed AIDS 28 to 62 months after the estimated date of seroconversion, supporting the hypothesis that there is a long latency between acquisition of viral infection and the development of clinical AIDS. This long latency could account for the significantly higher AIDS incidence in the New York cohort compared with other cohorts if the virus entered the New York homosexual population before it entered the populations from which the other cohorts were drawn. However, risk of AIDS development in different populations may also depend on the presence of as yet unidentified cofactors.

Determinants of retrovirus (HTLV-III) antibody and immunodeficiency conditions in homosexual men

A cohort of homosexual men at high risk of the acquired immunodeficiency syndrome (AIDS) was monitored to examine the relation between lifestyle, clinical conditions, T-lymphocyte subsets, and antibody to the AIDS-associated human retrovirus, human T-cell leukaemia virus III (HTLV-III). HTLV-III antibodies were present in 35 (53%) of the 66 subjects tested in June, 1982. 4 of the seronegative subjects had HTLV-III antibodies when re-tested one year later, a seroconversion rate of 1.2% per month. In the HTLV-III seropositive subjects, AIDS developed at a rate of 6.9% per year (minimum incidence of AIDS = 4.6% per year) and other clinical signs of immunodeficiency (lesser AIDS) at 13.1% per year. All 6 of the AIDS cases and at least 8 of the 10 lesser AIDS cases had detectable HTLV-III antibodies 1 week to 21 months before diagnosis. Of 24 other subjects with stable lymphadenopathy, 19 (79%) had or acquired HTLV-III antibodies. Lower helper T-cell counts were very closely related to HTLV-III seropositivity (r = -0.53, p = 0.0001), even in the 26 healthy subjects with no clinical abnormalities (r = -0.37, p = 0.07). In both univariate and multivariate analyses, the lifestyle risk factors for HTLV-III seropositivity were large number of homosexual partners (p less than or equal to 0.03) and receptive anal intercourse (p less than or equal to 0.03), with an apparent synergistic interaction between these two activities (chi 2 = 8.71, p = 0.003). These data suggest that frequent receptive anal intercourse with many homosexual partners predisposes to HTLV-III infection with the consequent emergence of lymphadenopathy and the various manifestations of lesser and fully fledged AIDS.