A community-based study of human immunodeficiency virus type 2 provirus load in rural village in West Africa

Prevalence and density of malaria parasitaemia amongst HIV Individuals in Warri, Nigeria

Background

Malaria parasite has been observed to be a common infection in Human Immunodeficiency virus (HIV), an increase malaria infection in adults.

Objective

This experimental study is sets to determine the prevalence and density of malaria parasitaemia in Warri community, South-Southern Nigeria.

Methods and Results

A total of 600 participants were screened for Human immunodeficiency virus and malaria parasite using WHO systems two and Geimsa staining technique for thick and thin blood films and absolute parasite counts done respectively. The prevalence rate of 38% and 39% were obtained for malaria parasite infection among HIVSP and HIV/span>SN respectively. The difference in malaria parasite infection was not statistically significant (P>0.05) between HIVSP and HIVSN. However, the mean parasite density in HIVSP was significant (P<0.05) when compared with HIVSN. The mean parasite densities of 2384 ± 747 and 1883 ± 645 were recorded for HIVSP and HIVSN respectively. The mean parasite densities of 2385 ± 782 and 2383 ± 717 observed for males and females respectively showed no statistical significant difference (P<0.05).

Conclusion

This study has shown a high prevalence of malaria parasite among the HIV infected subjects.

Quantification of HIV-2 DNA in Whole Blood

Time to AIDS infection is longer with HIV-2, compared to HIV-1, but without antiretroviral therapy both infections will cause AIDS-related mortality. In HIV-2 infection, monitoring of antiretroviral treatment (ART) efficacy is challenging since a large proportion of HIV-2-infected individuals displays low or undetectable plasma RNA levels. Hence, quantification of cellular DNA load may constitute an alternative method for monitoring ART efficacy. Moreover, sensitive HIV-2 DNA quantification protocols are also important for the characterization of the HIV-2 reservoirs, and ultimately for the development of HIV-2 cure strategies. We have developed a sensitive and robust HIV-2 DNA quantification protocol based on whole blood as DNA source, including normalization of leukocyte cell numbers using parallel quantification of the single copy porphobilinogen deaminase gene. The specificity and sensitivity of the assay was 100%. The limit of detection was 1 copy and limit of quantification was 5 copies. When applying this protocol to HIV-2 infected, it was found that HIV-2 viral DNA was detectable in individuals in whom viral RNA was undetectable or under quantification level. Thus, this method provides a sensitive approach to HIV-2 DNA viral quantification from whole blood of HIV-2 infected patients.

The presence of prolines in the flanking region of an immunodominant HIV-2 gag epitope influences the quality and quantity of the epitope generated

Both the recognition of HIV‐infected cells and the immunogenicity of candidate CTL vaccines depend on the presentation of a peptide epitope at the cell surface, which in turn depends on intracellular antigen processing. Differential antigen processing maybe responsible for the differences in both the quality and the quantity of epitopes produced, influencing the immunodominance hierarchy of viral epitopes. Previously, we showed that the magnitude of the HIV‐2 gag‐specific T‐cell response is inversely correlated with plasma viral load, particularly when responses are directed against an epitope, ₁₆₅DRFYKSLRA₁₇₃, within the highly conserved Major Homology Region of gag‐p26. We also showed that the presence of three proline residues, at positions 119, 159 and 178 of gag‐p26, was significantly correlated with low viral load. Since this proline motif was also associated with stronger gag‐specific CTL responses, we investigated the impact of these prolines on proteasomal processing of the protective ₁₆₅DRFYKSLRA₁₇₃ epitope. Our data demonstrate that the ₁₆₅DRFYKSLRA₁₇₃ epitope is most efficiently processed from precursors that contain two flanking proline residues, found naturally in low viral‐load patients. Superior antigen processing and enhanced presentation may account for the link between infection with HIV‐2 encoding the “PPP‐gag” sequence and both strong gag‐specific CTL responses as well as lower viral load.

Frequent intratype neutralization by plasma immunoglobulin a identified in HIV type 2 infection

Human immunodeficiency virus type 2 (HIV-2) is less transmissible and less pathogenic compared to HIV-1 and, when matched for CD4(+) T cell count, the plasma viral load in HIV-2-infected individuals is approximately one log lower than in HIV-1-infected individuals. The explanation for these observations is elusive, but differences in virus controlling immunity generated in the two infections may be contributing factors. In the present study, we investigated neutralization by immunoglobulin A (IgA), in parallel with IgG, purified from plasma of HIV-1, HIV-2, and HIV-1/HIV-2 dually (HIV-D) infected individuals. Neutralization was analyzed against HIV-1 and HIV-2 isolates using a plaque reduction assay. In HIV-2 infection, intratype-specific neutralization by IgA was frequently detected, although at a lesser magnitude then the corresponding IgG neutralizing titers. In contrast, neutralization by IgA could rarely be demonstrated in HIV-1 infection despite similar plasma IgA levels in both infections. In addition, IgA and IgG of HIV-D plasma neutralized the HIV-2 isolate more potently than the HIV-1 isolate, suggesting that the difference between neutralizing activity of plasma IgA and IgG depends on the virus itself. Taken together, these findings suggest that both IgA and IgG add to the potent intratype neutralizing activity detected in HIV-2 plasma, which may contribute to virus control in HIV-2 infection.

Population dynamics of HIV-2 in rural West Africa: comparison with HIV-1 and ongoing transmission at the heart of the epidemic

OBJECTIVES

To compare the population dynamics of HIV-2 and HIV-1, and to characterize ongoing HIV-2 transmission in rural Guinea-Bissau.

DESIGN

Phylogenetic and phylodynamic analyses using HIV-2 gag and env, and HIV-1 env sequences, combined with epidemiological data from a community cohort.

METHODS

Samples were obtained from surveys in 1989-1991, 1996-1997, 2003 and 2006-2007. Phylogenies were reconstructed using sequences from 103 HIV-2-infected and 56 HIV-1-infected patients using Bayesian Evolutionary Analysis by Sampling Trees (BEAST), a relaxed molecular clock and a Bayesian skyline coalescent model.

RESULTS

Bayesian skyline plots showed a strong increase in the 1990s of the HIV-1 effective population size (Ne) in the same period that the Ne of HIV-2 came into a plateau phase. The population dynamics of both viruses were remarkably similar following initial introduction. Incident infections were found more often in HIV-2 transmission clusters, with 55-58% of all individuals contributing to ongoing transmission. Some phylogenetically linked sexual partners had discordant viral loads (undetectable vs. detectable), suggesting host factors dictate the risk of disease progression in HIV-2. Multiple HIV-2 introductions into the cohort are evident, but ongoing transmission has occurred predominantly within the community.

CONCLUSION

Comparison of HIV-1 and HIV-2 phylodynamics in the same community suggests both viruses followed similar growth patterns following introduction, and is consistent with the hypothesis that HIV-1 may have played a role in the decline of HIV-2 via competitive exclusion. The source of ongoing HIV-2 transmission in the cohort appears to be new HIV-2 cases, rather than the pool of older infections established during the early growth of HIV-2.

HTLV-1 and HIV-2 infection are associated with increased mortality in a rural West African community

Background

Survival of people with HIV-2 and HTLV-1 infection is better than that of HIV-1 infected people, but long-term follow-up data are rare. We compared mortality rates of HIV-1, HIV-2, and HTLV-1 infected subjects with those of retrovirus-uninfected people in a rural community in Guinea-Bissau.

Methods

In 1990, 1997 and 2007, adult residents (aged ≥15 years) were interviewed, a blood sample was drawn and retroviral status was determined. An annual census was used to ascertain the vital status of all subjects. Cox regression analysis was used to estimate mortality hazard ratios (HR), comparing retrovirus-infected versus uninfected people.

Results

A total of 5376 subjects were included; 197 with HIV-1, 424 with HIV-2 and 325 with HTLV-1 infection. The median follow-up time was 10.9 years (range 0.0–20.3). The crude mortality rates were 9.6 per 100 person-years of observation (95% confidence interval 7.1-12.9) for HIV-1, 4.1 (3.4–5.0) for HIV-2, 3.6 (2.9–4.6) for HTLV-1, and 1.6 (1.5–1.8) for retrovirus-negative subjects. The HR comparing the mortality rate of infected to that of uninfected subjects varied significantly with age. The adjusted HR for HIV-1 infection varied from 4.0 in the oldest age group (≥60 years) to 12.7 in the youngest (15–29 years). The HR for HIV-2 infection varied from 1.2 (oldest) to 9.1 (youngest), and for HTLV-1 infection from 1.2 (oldest) to 3.8 (youngest).

Conclusions

HTLV-1 infection is associated with significantly increased mortality. The mortality rate of HIV-2 infection, although lower than that of HIV-1 infection, is also increased, especially among young people.

Potent autologous and heterologous neutralizing antibody responses occur in HIV-2 infection across a broad range of infection outcomes

Few studies have explored the role of neutralizing antibody (NAb) responses in controlling HIV-2 viremia and disease progression. Using a TZM-bl neutralization assay, we assessed heterologous and autologous NAb responses from a community cohort of HIV-2-infected individuals with a broad range of disease outcomes in rural Guinea-Bissau. All subjects (n = 40) displayed exceptionally high heterologous NAb titers (50% inhibitory plasma dilution or 50% inhibitory concentration [IC(50)], 1:7,000 to 1:1,000,000) against 5 novel primary HIV-2 envelopes and HIV-2 7312A, whereas ROD A and 3 primary envelopes were relatively resistant to neutralization. Most individuals also showed high autologous NAb against contemporaneous envelopes (78% of plasma-envelope combinations in 69 envelopes from 21 subjects), with IC(50)s above 1:10,000. No association between heterologous or autologous NAb titer and greater control of HIV-2 was found. A subset of envelopes was found to be more resistant to neutralization (by plasma and HIV-2 monoclonal antibodies). These envelopes were isolated from individuals with greater intrapatient sequence diversity and were associated with changes in potential N-linked glycosylation sites but not CD4 independence or CXCR4 use. Plasma collected from up to 15 years previously was able to potently neutralize recent autologous envelopes, suggesting a lack of escape from NAb and the persistence of neutralization-sensitive variants over time, despite significant NAb pressure. We conclude that despite the presence of broad and potent NAb responses in HIV-2-infected individuals, these are not the primary forces behind the dichotomous outcomes observed but reveal a limited capacity for adaptive selection and escape from host immunity in HIV-2 infection.

Potent intratype neutralizing activity distinguishes human immunodeficiency virus type 2 (HIV-2) from HIV-1

HIV-2 has a lower pathogenicity and transmission rate than HIV-1. Neutralizing antibodies could be contributing to these observations. Here we explored side by side the potency and breadth of intratype and intertype neutralizing activity (NAc) in plasma of 20 HIV-1-, 20 HIV-2-, and 11 dually HIV-1/2 (HIV-D)-seropositive individuals from Guinea-Bissau, West Africa. Panels of primary isolates, five HIV-1 and five HIV-2 isolates, were tested in a plaque reduction assay using U87.CD4-CCR5 cells as targets. Intratype NAc in HIV-2 plasma was found to be considerably more potent and also broader than intratype NAc in HIV-1 plasma. This indicates that HIV-2-infected individuals display potent type-specific neutralizing antibodies, whereas such strong type-specific antibodies are absent in HIV-1 infection. Furthermore, the potency of intratype NAc was positively associated with the viral load of HIV-1 but not HIV-2, suggesting that NAc in HIV-1 infection is more antigen stimulation dependent than in HIV-2 infection, where plasma viral loads typically are at least 10-fold lower than in HIV-1 infection. Intertype NAc of both HIV-1 and HIV-2 infections was, instead, of low potency. HIV-D subjects had NAc to HIV-2 with similar high potency as singly HIV-2-infected individuals, whereas neutralization of HIV-1 remained poor, indicating that the difference in NAc between HIV-1 and HIV-2 infections depends on the virus itself. We suggest that immunogenicity and/or antigenicity, meaning the neutralization phenotype, of HIV-2 is distinct from that of HIV-1 and that HIV-2 may display structures that favor triggering of potent neutralizing antibody responses.

HTLV-1 in rural Guinea-Bissau: prevalence, incidence and a continued association with HIV between 1990 and 2007

Background

HTLV-1 is endemic in Guinea-Bissau, and the highest prevalence in the adult population (5.2%) was observed in a rural area, Caió, in 1990. HIV-1 and HIV-2 are both prevalent in this area as well. Cross-sectional associations have been reported for HTLV-1 with HIV infection, but the trends in prevalence of HTLV-1 and HIV associations are largely unknown, especially in Sub Saharan Africa. In the current study, data from three cross-sectional community surveys performed in 1990, 1997 and 2007, were used to assess changes in HTLV-1 prevalence, incidence and its associations with HIV-1 and HIV-2 and potential risk factors.

Results

HTLV-1 prevalence was 5.2% in 1990, 5.9% in 1997 and 4.6% in 2007. Prevalence was higher among women than men in all 3 surveys and increased with age. The Odds Ratio (OR) of being infected with HTLV-1 was significantly higher for HIV positive subjects in all surveys after adjustment for potential confounding factors. The risk of HTLV-1 infection was higher in subjects with an HTLV-1 positive mother versus an uninfected mother (OR 4.6, CI 2.6-8.0). The HTLV-1 incidence was stable between 1990-1997 (Incidence Rate (IR) 1.8/1,000 pyo) and 1997-2007 (IR 1.6/1,000 pyo) (Incidence Rate Ratio (IRR) 0.9, CI 0.4-1.7). The incidence of HTLV-1 among HIV-positive individuals was higher compared to HIV negative individuals (IRR 2.5, CI 1.0-6.2), while the HIV incidence did not differ by HTLV-1 status (IRR 1.2, CI 0.5-2.7).

Conclusions

To our knowledge, this is the largest community based study that has reported on HTLV-1 prevalence and associations with HIV. HTLV-1 is endemic in this rural community in West Africa with a stable incidence and a high prevalence. The prevalence increases with age and is higher in women than men. HTLV-1 infection is associated with HIV infection, and longitudinal data indicate HIV infection may be a risk factor for acquiring HTLV-1, but not vice versa. Mother to child transmission is likely to contribute to the epidemic.

Dual infection with HIV-1 and HIV-2: double trouble or destructive interference?

HIV-1 and HIV-2 are two related retroviruses and, in regions where both infections are endemic, HIV-1/2 dual infection can occur. Several important questions arise about the interplay between these two viruses in a single host, including: what is the potential for HIV-1–HIV-2 recombinants to form, are there synergistic or inhibitory mechanisms that result in distinct viral replication dynamics when compared with HIV-1 or HIV-2 monoinfected individuals and what are the factors to consider when choosing antiretroviral regimes in HIV-1/2 dual-infected individuals? We summarize the relevant evidence to answer these questions, as well as indentify trends in prevalence and how the natural history of HIV-1/2 dual infection differs from that of HIV-1 or HIV-2 monoinfection. The epidemiological and in vitro evidence pertaining to the question of whether HIV-2 infection may protect against HIV-1 superinfection will also be addressed.

Two distinct epidemics: the rise of HIV-1 and decline of HIV-2 infection between 1990 and 2007 in rural Guinea-Bissau

OBJECTIVES

To assess changes in HIV incidence and prevalence in Caió, a rural area of Guinea-Bissau, between 1990 and 2007.

DESIGN

Three cross-sectional community surveys.

METHODS

In 1990, 1997, and 2007, surveys were conducted among adults. The prevalence of HIV-1 and of HIV-2 was estimated for each survey, and incidence rates were calculated for the first (1990-1997) and second period (1997-2007).

RESULTS

The HIV-1 incidence was approximately 4.5/1000 person-years in the two periods, whereas the HIV-2 incidence decreased from 4.7 (95% confidence interval 3.6-6.2) in the first to 2.0 (95% confidence interval 1.4-3.0) per 1000 person-years in the second period (P < 0.001). HIV-1 prevalence rose from 0.5% in 1990 to 3.6% in 2007, and HIV-2 prevalence decreased from 8.3% in 1990 to 4.7% in 2007. HIV-1 prevalence was less than 2% in 15 to 24 year olds in all surveys and was highest (7.2%) in 2007 among 45 to 54 year olds. The HIV-2 prevalence was fivefold higher in older subjects (> or =45 yr) compared with those less than 45 years in both sexes in 2007.

CONCLUSIONS

HIV-1 incidence is stable, and its prevalence is increasing, whereas HIV-2 incidence and prevalence are both declining. In contrast with what has been observed in other sub-Saharan countries, HIV-1 prevalence is lower in younger age groups than older age groups.

Higher homologous and lower cross-reactive Gag-specific T-cell responses in human immunodeficiency virus type 2 (HIV-2) than in HIV-1 infection

Human immunodeficiency virus type 2 (HIV-2) infection results in slower CD4(+) T-cell decline, lower plasma viral load levels, and hence slower progression of the disease than does HIV-1 infection. Although the reasons for this are not clear, it is possible that HIV-2 replication is more effectively controlled by host responses. We used aligned pools of overlapping HIV-1 and HIV-2 Gag peptides in an enhanced gamma interferon enzyme-linked immunospot assay to compare the levels of homologous and cross-reactive Gag-specific T-cell responses between HIV-1- and HIV-2-infected patients. HIV-2-infected patients showed broader and stronger homologous Gag-specific T-cell responses than HIV-1-infected patients. In contrast, the cross-reactive T-cell responses in HIV-2-infected patients were both narrower and weaker than those in HIV-1-infected patients, in line with overall weaker correlations between homologous and heterologous T-cell responses among HIV-2-infected patients than among HIV-1-infected patients. Cross-reactive responses in HIV-2-infected patients tended to correlate directly with HIV-1/HIV-2 Gag sequence similarities; this was not found in HIV-1-infected patients. The CD4(+) T-cell counts of HIV-2-infected patients correlated directly with homologous responses and inversely with cross-reactive responses; this was not found in HIV-1-infected patients. Our data support a model whereby high-level HIV-2-specific T-cell responses control the replication of HIV-2, thus limiting viral diversification and priming of HIV-1 cross-reactive T-cell responses over time. However, we cannot exclude the possibility that HIV-2 replication is controlled by other host factors and that HIV-2-specific T-cell responses are better maintained in the context of slow viral divergence and a less damaged immune system. Understanding the nature of immune control of HIV-2 infection could be crucial for HIV vaccine design.

Tenets of protection from progression to AIDS: lessons from the immune responses to HIV-2 infection

In the past 25 years, life survival curves of many countries have been remodeled owing to HIV infection. Both HIV-1 and HIV-2 can cause AIDS, yet patients infected with HIV-2 fare much better clinically and most will never experience detrimental effects of the infection. Despite over two decades of comprehensive research into vaccine development, a prophylactic vaccine is not yet realized. An essential missing link in the innovation of a successful vaccine strategy is the description of a favorable immune response that abolishes virus replication. Lessons learned from studying the role of the immune system in the long-term nonprogression characteristic of HIV-2 infection will offer insight into how a balanced immune response can protect from the destruction of the immune system associated with chronic HIV-1 infection.

Polyfunctional T cell responses are a hallmark of HIV-2 infection

HIV-2 is distinguished clinically and immunologically from HIV-1 infection by delayed disease progression and maintenance of HIV-specific CD4(+) T cell help in most infected subjects. Thus, HIV-2 provides a unique natural human model in which to investigate correlates of immune protection against HIV disease progression. Here, we report a detailed assessment of the HIV-2-specific CD4(+) and CD8(+) T cell response compared to HIV-1, using polychromatic flow cytometry to assess the quality of the HIV-specific T cell response by measuring IFN-gamma, IL-2, TNF-alpha, MIP-1beta, and CD107a mobilization (degranulation) simultaneously following Gag peptide stimulation. We find that HIV-2-specific CD4(+) and CD8(+) T cells are more polyfunctional that those specific for HIV-1 and that polyfunctional HIV-2-specific T cells produce more IFN-gamma and TNF-alpha on a per-cell basis than monofunctional T cells. Polyfunctional HIV-2-specific CD4(+) T cells were generally more differentiated and expressed CD57, while there was no association between function and phenotype in the CD8(+) T cell fraction. Polyfunctional HIV-specific T cell responses are a hallmark of non-progressive HIV-2 infection and may be related to good clinical outcome in this setting.

Low CD4 T-cell counts despite low levels of circulating HIV: Insights from the comparison of HIV-1 infected patients with a discordant response to antiretroviral therapy to patients with untreated advanced HIV-2 disease

A significant proportion of HIV-1+ patients with suppression of viremia under antiretroviral therapy fail to recover CD4(+) T-cell counts (ART-Discordants). Similarly, untreated HIV-2+ patients can also exhibit major CD4 depletion in spite of undetectable viremia. We characterize here the immunological disturbances associated with major CD4-lymphopenia in these two scenarios as compared to untreated viremic HIV-1+ patients with similar CD4-lymphopenia and HIV-1+ patients with successful immunological and virological responses under ART. Low CD4 counts were associated with major naive CD4 and CD8 depletion, irrespective of type of infection or ART-exposure. However, ART-Discordants exhibited lower levels of T-cell activation as compared to both untreated HIV-2 and HIV-1 cohorts, and a less marked increase in circulating IL-7 despite similar CD4 depletion. Nevertheless, ART-Discordants showed a preserved Bcl-2 expression, suggesting increased IL-7 consumption, which in conjunction with the relatively lower T-cell activation may contribute to their CD4 count stability and low rate of opportunistic infections.

Vaccinia scars associated with improved survival among adults in rural Guinea-Bissau

BACKGROUND

In urban Guinea-Bissau, adults with a vaccinia scar had better survival but also a higher prevalence of HIV-2 infection. We therefore investigated the association between vaccinia scar and survival and HIV infection in a rural area of Guinea-Bissau.

METHODOLOGY/PRINCIPAL FINDINGS

In connection with a study of HIV in rural Guinea-Bissau, we assessed vaccinia and BCG scars in 193 HIV-1 or HIV-2 infected and 174 uninfected participants. Mortality was assessed after 2(1/2)-3 years of follow-up. The analyses were adjusted for age, sex, village, and HIV status. The prevalence of vaccinia scar was associated with age, village, and HIV-2 status but not with sex and schooling. Compared with individuals without any scar, individuals with a vaccinia scar had better survival (mortality rate ratio (MR) = 0.22 (95% CI 0.08-0.61)), the MR being 0.19 (95% CI 0.06-0.57) for women and 0.40 (95% CI 0.04-3.74) for men. Estimates were similar for HIV-2 infected and HIV-1 and HIV-2 uninfected individuals. The HIV-2 prevalence was higher among individuals with a vaccinia scar compared to individuals without a vaccinia scar (RR = 1.57 (95% CI 1.02-2.36)).

CONCLUSION

The present study supports the hypothesis that vaccinia vaccination may have a non-specific beneficial effect on adult survival.

Protective immunity against HIV infection: lessons from HIV-2 infection

Despite two decades of intensive research, the correlates of protective immunity to HIV-1 infection remain elusive. Much less attention has been paid to the related human virus strain, HIV-2, which can cause AIDS, but does not usually do so in the majority of infected people. What can be learned from HIV-2 infection about how the human host can peacefully coexist with a pathogenic retrovirus?

An adaptation of recombinant vaccinia-based ELISPOT and intracellular cytokine staining for a comparative measurement of cellular immune responses in HIV-1 and HIV-2 infections in West Africa

An efficient and quantitative tool for rapid assessment of human immunodeficiency virus (HIV)-induced cellular immune responses is important for resource-limited settings, such as in sub-Saharan Africa. Modifications are required to previously reported methods for evaluating ex-vivo antigen-specific cellular responses based on direct recombinant vaccinia virus (rVV) stimulation of peripheral blood mononuclear cells (PBMCs) by enzyme linked immunosorbent assay (ELISPOT) and by flow cytometry intracellular cytokine assay (ICA). We made such modifications in order to detect specific responses and compared quantitative cellular immune responses in HIV-1 and HIV-2 infected Gambians. The sensitivity of the rVV-based ELISPOT assay was on average 1.25 interferon (IFN)-gamma spot forming cells (SFC) per 50 000 PBMCs specific for either infection, and 5 IFN-gamma-secreting CD8+ T cells/50 000 in the ICA. The level of IFN-gamma SFC detected by ELISPOT and by ICA were correlated (P < 0.02). ICA detected pol-specific responses in 88% and 67% of HIV-1 and HIV-2 subjects, respectively, and gag-specific responses in more than 80% of both infections. Lower proportions of responders were obtained with ELISPOT, for which pol responses were present in 60% of HIV-1 and 46% of HIV-2 infected patients, and gag responses in 55% and 69%, respectively. The assays did not show any significant difference in cellular immune responses between HIV-1 and HIV-2 infected subjects with CD4% >or= 20%. These outcomes are comparable with results obtained using standard techniques and thus this method is a suitable, rapid and less expensive assessment of cellular immunity.

Increased frequency of circulating CCR5+ CD4+ T cells in human immunodeficiency virus type 2 infection

CCR5 expression determines susceptibility to infection, cell tropism, and the rate of human immunodeficiency virus type 1 (HIV-1) disease progression. CCR5 is also considered the major HIV-2 coreceptor in vivo, in spite of broad coreceptor use in vitro. Here we report a significantly increased proportion of memory-effector CD4 T cells expressing CCR5 in HIV-2-infected patients correlating with CD4 depletion. Moreover, HIV-2 proviral DNA was essentially restricted to memory-effector CD4, suggesting that this is the main target for HIV-2. Similar levels of proviral DNA were found in the two infection categories. Thus, the reduced viremia and slow rate of CD4 decline that characterize HIV-2 infection seem to be unrelated to coreceptor availability.

Maintenance of HIV-specific CD4+ T cell help distinguishes HIV-2 from HIV-1 infection

Unlike HIV-1-infected people, most HIV-2-infected subjects maintain a healthy CD4+ T cell count and a strong HIV-specific CD4+ T cell response. To define the cellular immunological correlates of good prognosis in HIV-2 infection, we conducted a cross-sectional study of HIV Gag-specific T cell function in HIV-1- and HIV-2-infected Gambians. Using cytokine flow cytometry and lymphoproliferation assays, we show that HIV-specific CD4+ T cells from HIV-2-infected individuals maintained proliferative capacity, were not terminally differentiated (CD57-), and more frequently produced IFN-gamma or IL-2 than CD4+ T cells from HIV-1-infected donors. Polyfunctional (IFN-gamma+/IL-2+) HIV-specific CD4+ T cells were found exclusively in HIV-2+ donors. The disparity in CD4+ T cell responses between asymptomatic HIV-1- and HIV-2-infected subjects was not associated with differences in the proliferative capacity of HIV-specific CD8+ T cells. This study demonstrates that HIV-2-infected donors have a well-preserved and functionally heterogeneous HIV-specific memory CD4+ T cell response that is associated with delayed disease progression in the majority of infected people.

Human immunodeficiency virus types 1 and 2 have different replication kinetics in human primary macrophage culture

This study compares the replication of primary isolates of human immunodeficiency virus type 2 (HIV-2) and type 1 (HIV-1) in monocyte-derived macrophages (MDMs). Eleven HIV-2 and five HIV-1 primary isolates that use CCR5, CXCR4 or both coreceptors to enter cells were included. Regardless of coreceptor preference, 10 of 11 HIV-2 viruses could enter, reverse transcribe and produce fully infectious virus in MDMs with efficiency equal to that in peripheral blood mononuclear cells. However, the kinetics of replication of HIV-2 compared with HIV-1 over time were distinct. HIV-2 had a burst of virus replication 2 days after infection that resolved into an apparent 'latent state' at day 3. HIV-1, however, continued to produce infectious virions at a lower, but steady, rate throughout the course of infection. These results may have implications for the lower pathogenesis and viral-load characteristics of HIV-2 infection.

Distinct profile of T cell activation in HIV type 2 compared to HIV type 1 infection: differential mechanism for immunoprotection

The mechanism for the lower rate of disease progression in HIV-2 infection remains undefined. We evaluated T cell activation in a cohort of HIV-infected commercial sex workers in Dakar, Senegal. CD8+ T cell activation was significantly lower in HIV-2- compared to HIV-1-infected volunteers and both groups displayed higher activation levels compared to seronegative individuals. In contrast, CD4+ T cell activation was similar between the HIV-1 and HIV-2 groups and significantly higher compared to the seronegative group. Interestingly, HIV-2-positive volunteers with evidence of Gag-specific CD8+ T cell responses displayed lower CD4+ T cell activation. Our data suggest that the distinct T cell activation profile in HIV-2-positive individuals may reflect on the presence of effective host immune responses in HIV-2 infection.

Factors associated with clinical progression in HIV-2 infected-patients: the French ANRS cohort

OBJECTIVES

To identify factors associated with clinical progression in HIV-2 infected patients.

DESIGN

French prospective cohort initiated in 1994.

METHODS

Follow-up data are collected twice a year; viral load is assessed once a year by cellular viraemia, quantitative proviral DNA and plasma RNA. A Cox proportional-hazards model was used for studying baseline factors associated with clinical progression.

RESULTS

By December 2001, 217 patients had been enrolled. At inclusion, 80%, 6% and 14% were Centers for Disease Control and Prevention (CDC) group A, B and C, respectively. Median CD4 cell count was 436 x 10(6)/l. In the 48% of positive specimens, the median plasma RNA titre was 3.0 log10 copies/ml. Mean follow-up of the 179 patients seen at least twice was 34.4 months. Of these 13 died and nine progressed to group C. Ninety-three (52%) received antiretroviral therapy during a mean of 33 months, including a protease inhibitor in 48%. The probability of remaining AIDS-free was 97% and 95% at 1 and 3 years, respectively. Independent variables associated with clinical progression were age > or = 40 years [hazard ratio (HR), 11; 95% confidence interval (CI), 1.4-91.8; P = 0.03] and plasma RNA (HR, 2.5 per additional log10 copies/ml; 95% CI, 1.3-4.7, P < 0.01). Prior group B symptoms and CD4 cell count < 200 x 10(6)/l were associated with progression to AIDS. AIDS and plasma RNA were predictive of death.

CONCLUSION

Considering the limited progression rate of HIV-2 infection, combined antiretroviral therapy should be discussed in patients with high plasma RNA titres, which threshold value remains to be defined. It is recommended in case of AIDS, CDC group B symptoms or CD4 cell count < 200 x 10(6)/l.

Low level viremia and high CD4% predict normal survival in a cohort of HIV type-2-infected villagers

A community-based study of human immunodeficiency virus type 2 (HIV-2) infection was conducted in a rural village in northern Guinea Bissau, West Africa to assess the relationship between plasma HIV-2 RNA levels, CD4 lymphocyte percentage, and survival over an 8-year period. The cohort of 133 HIV-2-infected individuals and 160 HIV-uninfected controls enrolled in 1991 were followed up at home until 1998. Thirty-one (23%) HIV-2-infected and 24 (16%) HIV-uninfected individuals died over the follow-up period (mortality hazard ratio 1.7, 95% CI 1.0, 2.9; p= 0.06). In HIV-2-infected individuals, the median HIV-2 RNA level was 347 copies/ml and the mean CD4% was 28.6. Both plasma viremia and CD4% were independent predictors of survival, with hazard ratios increasing by 1.6 (95% CI, 1.1, 2.3) for each log(10) increase of plasma viremia and 1.7 (1.1, 2.6) for each 10% decrease of CD4%. Infected subjects with a plasma viral load >or= the median (347 copies/ml) and a CD4% <or= the mean (28.6%) had a mortality hazard ratio of 3.1 (95% CI 1.7, 5.8) compared to uninfected controls, whereas the remaining infected subjects had a mortality rate similar to uninfected controls, the mortality hazard ratio being 1.0 (95% CI, 0.5, 2.1.) In those who survived between 1991 and 1996, HIV-2 RNA levels were unchanged overall and CD4 lymphocyte counts remained high. In conclusion, baseline HIV-2 RNA levels predicted a normal survival for the majority, with low and stable levels of plasma viremia characterizing HIV-2 infections in this rural West African community.

Plasma RNA viral load in human immunodeficiency virus type 2 subtype A and subtype B infections

Human immunodeficiency virus type 2 (HIV-2) is much less pathogenic than HIV-1, and HIV-2 infection is associated with plasma viral loads significantly lower than those found in HIV-1 infection. We have developed a real-time quantitative PCR method for measuring the HIV-2 RNA load that covers the range of genetic diversity of HIV-2 isolates and that detects extremely low viral loads. Samples from 49 patients were studied. Proviral DNA was first detected and quantified. The strains that were detected were then genotyped: 21 patients were infected with HIV-2 subtype A and 15 patients were infected with HIV-2 subtype B; 1 patient was infected with a highly divergent strain. Env PCR failed for the remaining 12 patients, so subtypes could not be determined. For viral RNA quantification, a stock of HIV-2 strain NIHZ, which was counted by electron microscopy, was used as the standard. Several primer sets targeting the highly conserved gag region were evaluated. Various primer combinations failed to amplify subtype B strains. With the final primer pair selected, which detected both subtype A and subtype B strains, the sensitivity of the assay was 100% at a viral load of 250 copies/ml and 66% at a viral load of 125 copies/ml. We found a correlation between the CD4(+)-cell count, the clinical stage, and the plasma HIV-2 RNA level. The median plasma HIV-2 RNA value for the 33 asymptomatic patients was 2.14 log(10), whereas it was 3.1 log(10) for the 16 patients with AIDS (P < 0.01). Proviral DNA was detectable in 18 symptom-free patients with high CD4(+)-cell counts, in whom viral RNA was undetectable.

Increased prevalence of HTLV-1 among HIV-2-infected women but not HIV-2-infected men in rural Guinea-Bissau

OBJECTIVE

To assess the prevalence of HTLV infection and its association with HIV and other potential risk factors.

DESIGN AND SETTING

A cross-sectional survey and a case-control study in a rural community in Guinea-Bissau.

METHODS

A total of 2770 people were included in an HIV and HTLV seroepidemiologic survey. Three hundred of these participants were selected for a case-control study on HIV-2. Sera from both studies were tested for HTLV.

RESULTS

In all, 2501 and 298 subjects in the survey and case-control study, respectively, were tested for HTLV. Overall HTLV-1 prevalence was 5.2% and it was higher in women (odds ratio [OR], 1.36; confidence interval [CI], 0.92-2.02). Apart from an infected spouse, no significant risk factors could be identified for men. In women, HIV-2 infection (adjusted OR, 5.58; CI, 3.09-10.1), having an infected spouse, and area of residence were significantly associated with HTLV-1 infection. The association between HTLV-1 and HIV-2 was significantly different for men and women (test of interaction, p =.002).

CONCLUSIONS

In women, the most important determinant of HTLV-1 seropositivity was HIV-2 infection. Because the pattern was significantly different for men and women, common sexual risk factors may not be sufficient to explain the co-occurrence of HIV-2 and HTLV-1 in women. These observations may have implications in geographic areas where both types of retroviruses are prevalent.

Quantification of proviral load of human immunodeficiency virus type 2 subtypes A and B using real-time PCR

We have developed and evaluated a new method to quantify human immunodeficiency virus type 2 (HIV-2) proviral DNA based on LightCycler real-time PCR. The assay has a detection limit of 5 copies/10(5) peripheral blood mononuclear cells (PBMC) and is insensitive to HIV-2 strain variability: HIV-2 subtypes A and B are both recognized and quantified. The intra- and interassay coefficients of variation range from 16 to 40% for high provirus concentrations (5 x 10(5) copies) and from 41 to 39% for low concentrations (5 copies). We used this method to compare the proviral DNA load and viral RNA load in plasma with clinical and immunological status for 29 patients infected by HIV-2 (subtype A in 17 and subtype B in 12). The proviral load (median, 201 copies/10(5) PBMC) was similar to that reported for HIV-1 infection. The median proviral loads did not correlate with the CD4(+) cell count categories and were as follows for CD4(+) cell counts of >400, 200 to 400, and <200 cells/mm(3), respectively: 121 copies/10(5) PBMC (n = 8; range, <5 to 712 copies/10(5) PBMC); 114 copies/10(5) PBMC (n = 9; range, <5 to 1,907 copies/10(5) PBMC); and 285 copies/10(5) PBMC (n = 12; range, 53 to 2,524 copies/10(5) PBMC). Proviral load did not correlate with plasma HIV-2 RNA positivity. As HIV-2 is considered to replicate less efficiently than HIV-1, these high proviral loads might be explained by the proliferation of infected cells.

A systematic review of the epidemiologic interactions between classic sexually transmitted diseases and HIV: how much really is known?

BACKGROUND

Many studies have explored the role of "classic" sexually transmitted diseases (STDs) in determining the pattern of HIV epidemics. However, the many different STDs may contribute in different ways, at different magnitudes.

GOAL

To review available studies on the bidirectional interactions of HIV and STDs to explore the extent of current knowledge on the different influences of the varied STDs in heterosexual HIV epidemics.

METHODS

Longitudinal studies on susceptibility and controlled studies on infectiousness and duration of disease identified on electronic databases through reference lists and citation indices up to the end of 1999 were systematically reviewed, including meta-analyses assessing the influence of STDs on susceptibility to HIV.

RESULTS

Studies have a clear publication bias with a significant result that hinders robust interpretation. However, genital ulcerative disease appears to have a greater impact than nonulcerative disease, and men are more affected than women by the effects of STDs on susceptibility to HIV. There is evidence that STDs increase the infectiousness of HIV from men to women, whereas the evidence is more equivocal for the infectiousness of women. Few studies identify the impact of different STDs, and there is a marked lack of studies investigating the impact of HIV infection on the transmission of other STDs.

CONCLUSIONS

A large body of work has measured the association between STDs and HIV. However, publication bias and gaps in the focus of studies mean that a detailed, quantitative understanding of the interaction requires much more attention.

Contribution of immune activation to the pathogenesis and transmission of human immunodeficiency virus type 1 infection

The life cycle of human immunodeficiency virus type 1 (HIV-1) is intricately related to the activation state of the host cells supporting viral replication. Although cellular activation is essential to mount an effective host immune response to invading pathogens, paradoxically the marked systemic immune activation that accompanies HIV-1 infection in vivo may play an important role in sustaining phenomenal rates of HIV-1 replication in infected persons. Moreover, by inducing CD4+ cell loss by apoptosis, immune activation may further be central to the increased rate of CD4+ cell turnover and eventual development of CD4+ lymphocytopenia. In addition to HIV-1-induced immune activation, exogenous immune stimuli such as opportunistic infections may further impact the rate of HIV-1 replication systemically or at localized anatomical sites. Such stimuli may also lead to genotypic and phenotypic changes in the virus pool. Together, these various immunological effects on the biology of HIV-1 may potentially enhance disease progression in HIV-infected persons and may ultimately outweigh the beneficial aspects of antiviral immune responses. This may be particularly important for those living in developing countries, where there is little or no access to antiretroviral drugs and where frequent exposure to pathogenic organisms sustains a chronically heightened state of immune activation. Moreover, immune activation associated with sexually transmitted diseases, chorioamnionitis, and mastitis may have important local effects on HIV-1 replication that may increase the risk of sexual or mother-to-child transmission of HIV-1. The aim of this paper is to provide a broad review of the interrelationship between immune activation and the immunopathogenesis, transmission, progression, and treatment of HIV-1 infection in vivo.

Sequence specificity of the human immunodeficiency virus type 2 (hiv-2) long terminal repeat u3 region in vivo allows subtyping of the principal hiv-2 viral subtypes a and b

Sequences from the nef/LTR overlap region of the human immunodeficiency virus type 2 (HIV-2) genome were amplified from uncultured peripheral blood mononuclear cells (PBMCs) from 40 HIV-2-infected individuals in The Gambia, West Africa. Additional sequences from the plasma of three blood donors were also derived. Analysis of HIV-2 U3 LTR transcription factor elements (PuB-1, p-ets, PuB-2, peri-kappa B, and NF-kappa B sites) indicated a relatively high level of conservation in vivo. The region immediately 3' of the nef termination codon, which exhibits clade-dependent specificity, was targeted by PCR to differentiate HIV-2 subtype A from subtype B infections, the two principal clinical HIV-2 subtypes. All clinical samples analyzed (n = 43) from The Gambia were identified as HIV-2 subtype A by a combination of LTR sequence analysis and subtype-specific amplification of subtypes A and B. Differential PCR amplification of the HIV-2 U3 LTR region represents a rapid means of differentiating subtype A from subtype B infections, the two dominant HIV-2 subtypes that are important in human disease.

Development of a real-time quantitative RT-PCR for the detection of HIV-2 RNA in plasma

An assay is described for the quantification of human immunodeficiency virus type 2 (HIV-2) RNA in EDTA plasma based on RT-PCR using the Taqman real-time PCR detection method. As standard, an electron microscopically counted virus stock of HIV-2 strain NIHZ was used. The lower detection limit is 5 # 102 HIV-2 RNA copies per ml of EDTA plasma. The assay is linear within the range required (5 # 102-106 HIV-2 RNA copies/ml of EDTA plasma) with an intra assay variability of 2.5% and an inter-assay variability ranging from 2% at 106 copies to 7.5% at the lower detection limit. Three primer/probe combinations were developed to circumvent false negative samples due to nucleotide variation in the target sequence. Using these primer/probe sets enabled the detection of HIV-2 DNA sequences from all HIV-2 seropositive individuals and two out of five dual human immunodeficiency virus type 1 (HIV-1) and HIV-2 seropositive individuals visiting the University Hospital Rotterdam.

Lower HIV-2 plasma viral loads may explain differences between the natural histories of HIV-1 and HIV-2 infections

To explain the low transmissibility and pathogenicity of HIV-2 infection's plasma viral loads in both HIV-1- and HIV-2-infected persons were compared by using the polymerase chain reaction (PCR)-based Amp-RT assay to measure levels of reverse transcriptase (RT) activity. The study comprised a total of 155 HIV-infected-people including 58 who were infected with HIV-2 with CD4+ cell counts <500 x 106/L (n = 15), CD4+ cell counts >500 x 106/L (n = 26), or with tuberculosis (TB; n = 17), and 97 HIV-1-infected people with CD4+ cell counts <500 x 106/L (n = 32), CD4+ cell counts >500 x 106/L (n = 25), or TB (n = 40). Among persons with CD4+ cell counts <500 x 106/L, 11 (73.3%) of 15 HIV-2-infected persons had detectable plasma RT activity compared with 25 (78.1%) of 32 HIV-1-infected persons (p =.725). However, the median HIV-2 plasma RT activity in this group was significantly lower (2561 x 10-10 U/ml; p =.036; detectable range, 1712-644,868 x 10-10 U/ml) than the RT activity of HIV-1-infected persons with similar CD4+ cell counts (13,241 x 10-10 U/ml; detectable range, 8482-1,478,880 x 10-10 U/ml). Among TB patients, 10 (58.8%) of 17 HIV-2-infected persons had detectable plasma RT activity compared with 30 (75%) of 40 HIV-1-infected persons (p =.342). In contrast, among patients with CD4+ cell counts >500 x 106/L, none of 26 HIV-2-infected persons had detectable RT activity compared with 13 (52%) of 25 HIV-1-infected persons (p <.001). Our data suggest that unlike HIV-1 infection, HIV-2 infections with CD4+ cell counts >500 x 106/L are associated with a low level of viral replication, which may explain the longer clinical latency and lower transmissibility seen in HIV-2 infection.

Plasma RNA viral load predicts the rate of CD4 T cell decline and death in HIV-2-infected patients in West Africa

OBJECTIVE

To examine whether the levels of plasma RNA and DNA provirus predict the rate of CD4 cell decline and patient death.

DESIGN

Retrospective analysis of HIV-2 cohort subjects.

METHODS

Fifty-two subjects were recruited between January 1991 and December 1992. HIV-2 RNA levels in plasma and DNA levels in peripheral blood mononuclear cells (PBMC) were measured using in-house quantitative PCR assays. The annual rate of CD4 cell decline was calculated using the least-squares method. The survival data on 31 December 1997 were used.

RESULTS

The mean percentage of CD4 cells at baseline was 30.7 (SD, 9.5). In a linear regression model, the annual rate of CD4 cell decline was 1.76 CD4% faster for every increase in one log10 RNA copies/ml [95% confidence interval (CI), 0.81-2.7; P = 0.0006; r = 0.46; n = 52] and 1.76 CD4% faster for every increase in log10 DNA copies/10(5) PBMC (95% CI 0.46-3.1; P = 0.01; r = 0.33; n = 42). In a multiple linear regression model, RNA load was related to CD4 decline independently of DNA load (P = 0.02). The overall mortality rate was 7.29/100 person-years. In a Cox regression model, the hazard rate increased by 2.12 for each log10 increase in RNA load (95% CI, 1.3-3.5; P = 0.0023) but only by 1.09 for each log10 increase in DNA load (95% CI, 0.64-1.87; P = 0.8).

CONCLUSION

This longitudinal study shows for the first time that a baseline HIV-2 RNA load predicts the rate of disease progression. HIV-2-infected patients with a high viral load may need to be treated as vigorously as HIV-1 patients.

Low plasma human immunodeficiency virus type 2 viral load is independent of proviral load: low virus production in vivo

Levels of virus in the plasma are closely related to the pathogenicity of human immunodeficiency virus type 1 (HIV-1). HIV-2 is much less pathogenic than HIV-1, and infection with HIV-2 leads to significantly lower plasma viral load. To identify the source of this difference, we measured both viral RNA and proviral DNA in matched samples from 34 HIV-2-infected individuals. Nearly half had undetectable viral RNA loads (<100 copies/ml), but levels of proviral DNA were relatively high and confirmed that quantities of provirus in HIV-1 and HIV-2 infection were similar. Overall, HIV-2 proviral DNA load did not correlate with viral RNA load, and higher viral RNA load was associated with increased production of plasma virus from the proviral template. These results suggest that low viral load in HIV-2 infection is due to decreased rates of viral production, rather than differences in target cell infectivity.

Proviral load and immune function in blood and lymph node during HIV-1 and HIV-2 infection

Proviral load as well as lymphocyte phenotype and function were compared in peripheral blood and lymph node compartments of 17 HIV-1, 12 HIV-2 and three dually infected patients with lymphadenopathy. The mean percentage (95% confidence interval (CI)) of CD4+ cells was higher in lymph node mononuclear cells (LNMC) than in peripheral blood mononuclear cells (PBMC) in both infections, being 26.7% (21. 1%, 32.3%) and 15.3% (10.4%, 20.2%), respectively, for HIV-1-infected patients (P = 0.0001) and 32.3% (22.7%, 41.9%) and 22. 1% (13.6%, 30.6%), respectively, for HIV-2-infected patients (P = 0. 02). In both types of infection, proviral load adjusted for number of CD4+ cells was higher in LNMC than in PBMC: the geometric mean (95% CI) was 8937 (4991; 16 003) and 4384 (2260; 8503), respectively, for HIV-1 patients (P = 0.02) and 1624 (382; 6898) and 551 (147; 2058) DNA copies, respectively, for HIV-2 patients (P = 0.05). Proviral load in both compartments was closely correlated (HIV-1, r = 0.60, P = 0.01; and HIV-2, r = 0.83, P = 0.0003). In both infections, proliferation and interferon-gamma (IFN-gamma) production in response to purified protein derivative (PPD) was lower in LNMC than in PBMC, both of which, in turn, were lower than in healthy controls. These results indicate that in HIV-2 as in HIV-1 infection, infected cells have a tropism for the lymph nodes resulting in higher viral load in this compartment and lower lymphocyte responses to the recall antigen PPD which may increase susceptibility to tuberculosis.

Quantitation of human immunodeficiency virus type 2 DNA in peripheral blood mononuclear cells by using a quantitative-competitive PCR assay

A new quantitative-competitive PCR-based human immunodeficiency virus type 2 (HIV-2) proviral DNA assay (QC-PCR) was developed and used to determine the proviral load in HIV-2-infected individuals. Proviral load varied considerably, with means of 1,831 copies per 10(6) peripheral blood mononuclear cells for asymptomatic subjects (n = 19) and 2,587 for AIDS patients (n = 2). HIV-2 viral and proviral loads also varied significantly over time in asymptomatic patients. These data suggest that a high level of virus replication occurs throughout the asymptomatic phase of HIV-2 infection.

Mortality among human immunodeficiency virus type 2-positive villagers in rural Guinea-Bissau is correlated with viral genotype

We present the results of a 6-year study of 131 human immunodeficiency virus (HIV) type 2 (HIV-2)-infected individuals from a rural population in Guinea-Bissau. Proviral DNA sequences 1.3 kb in length were obtained from each individual and, together with clinical data, including proviral load and CD4 and CD8 levels, were used to assess whether viral genotype influences clinical outcome. With a phylogenetic model, a correlation was found between viral genotype and mortality; this correlation was not due to confounding factors, such as age-specific viral strains or cohabitation of patients. The data provide strong evidence for the involvement of viral genetic factors in determining HIV disease progression in vivo. The pattern of association found suggests that virulence factors are multiple and scattered throughout the HIV-2 genome and can be rapidly gained or lost by the virus through a combination of mutation and recombination. These findings may lead to the identification of viral determinants of HIV disease progression.

Improved detection of HIV-2 proviral DNA in dually seroreactive individuals by PCR

OBJECTIVE

To improve the detection rate of HIV-2 proviral DNA in primary uncultured peripheral blood mononuclear cells (PBMC) of HIV-2-seroreactive and HIV-1-HIV-2 dually seroreactive individuals.

MATERIALS AND METHODS

Two newly designed HIV-2 PCR primer pairs in the long terminal repeat (LTR) gag and gag-pol regions and a previously described env and LTR HIV-2 PCR primer pairs were tested on samples from 66 confirmed HIV-2-seropositive individuals (The Gambia, 40; Côte d'Ivoire, 17; Guinea-Bissau, nine), 209 dually seroreactive individuals (The Gambia, 82; Côte d'Ivoire, 127), 24 genetically characterized isolated HIV-1 strains (group M subtypes A-H and group O), one simian immunodeficiency virus (SIV) strain cpz, 10 HIV-2 isolates (subtype A, B and unidentified), two SIVsm isolates, and 10 seronegative samples.

RESULTS

All HIV-2 primers evaluated showed 100% specificity since there was no amplification observed with 24 HIV-1, one SIVcpz and 10 seronegative samples. One single copy of the HIV-2 genome could be detected with all outer primer pairs as well as all inner primer pairs on one PCR round used. Sensitivity of primers (at least one of the four primer pairs was positive) to HIV-2-seropositive samples was 100% (all nine) in Guinea-Bissau, 71% (12/17) in Côte d'Ivoire, 100% (all 20) in Gambian AIDS patients, and 85% (17/20) in Gambian pregnant women. Doubling the PBMC of dually seroreactive individuals from 7.5 x 10(4) to 1.5 x 10(5) in the PCR revealed the presence of both HIV-1 and 2 proviral DNA in 72% (92/127) in Côte d'Ivoire and 72% (59/82) in The Gambia. By doubling the number of PBMC, HIV-2 detection in dually seroreactive individuals by PCR was increased from 65 to 77% in Côte d'Ivoire and from 67 to 83% in The Gambia.

CONCLUSIONS

The use of 1.5 x 10(5) primary uncultured PBMC and the newly designed HIV-2 primer pairs allowed us to document the highest percentage (72%) ever reported of HIV-1-HIV-2 dual infections amongst HIV-1-HIV-2 dually seroreactive individuals in Côte d'Ivoire and The Gambia. Improved detection of HIV-2 proviral DNA, rather than exposure to both viruses, infection with only one virus, or infection with a unique third virus containing epitopes common to both HIV-1 and HIV-2, contributes to a more accurate monitoring of the prevalence of HIV-1-HIV-2 dual infections.

HIV-2 and T cell recognition

HIV-2 is less pathogenic and less transmissible than HIV-1. Recent research in relation to deletions in the HIV nef gene and to immune cross-reactions between infections by HIV-2, HIV-1 and simian immunodeficiency virus suggests that T cell recognition and the control of viral replication may be more efficient in HIV-2 infection than in HIV-1 infection. These insights may be crucial to the design of effective vaccines.

The compromised traveler

Compromised travelers represent a diverse and challenging group of individuals. They include HIV-infected patients who are at risk for potentially adverse reactions to immunizations, and new exposures to enteric water-borne opportunistic pathogens associated with chronic infections. Such travelers may encounter unfamiliar opportunistic fungi and classical tropical infections, such as leishmaniasis, whose pathogenesis can be enhanced by the presence of prior HIV infection. Other immunocompromised groups include those who are functionally or anatomically asplenic, and patients who are iatrogenically immunosuppressed from medications utilized for solid organ transplantation, chemotherapy, or treatment of malignancies. This population of travelers also includes those with diabetes mellitus who may require adjustments in their dosing, administration, and possibly even the types of insulin used on their trips. These patients are also at greater risk for acquisition of tuberculosis, severe community-acquired pneumonia, urinary tract infections, and pyomyositis. Older travelers present both the infectious disease and travel medicine specialist with issues such events, malignancy-related infections, myocardial infarction, and other forms of cardiopulmonary compromise, which the authors address in this article.

The associations between cervicovaginal HIV shedding, sexually transmitted diseases and immunosuppression in female sex workers in Abidjan, Côte d'Ivoire

OBJECTIVE

To measure the frequency and associated factors of cervicovaginal HIV shedding and to determine the impact of sexually transmitted disease (STD) treatment on HIV shedding.

DESIGN

Cross-sectional study with 1-week follow-up.

SETTING

Confidential clinic for female sex workers in Abidjan, Côte d'Ivoire.

PARTICIPANTS

A total of 1201 female sex workers.

INTERVENTIONS

STD treatment based on clinical signs.

MAIN OUTCOME MEASURES

HIV serostatus; cervicovaginal HIV shedding at enrollment and at 1-week follow-up; STD status at enrollment and at 1-week follow-up.

RESULTS

Cervicovaginal shedding of HIV-1 in HIV-1-seropositive women was more frequent (96 out of 404, 24%) than shedding of HIV-2 in HIV-2-seropositive women [one out of 21, 5%; odds ratio (OR), 6.2; 95% confidence interval (CI), 1.0-261]. Among 609 HIV-1-seropositive or dually seroreactive women, HIV-1 shedding was significantly more frequent in immunosuppressed women [adjusted OR (AOR), 6.3; 95% CI, 3.4-11.9; and AOR, 2.9; 95% CI, 1.6-5.0 for CD4 < 14% and CD4 14-28%, respectively, versus CD4 > 28%], and in women with Neisseria gonorrhoeae (AOR, 1.9; 95% CI, 1.2-3.0), those with Chlamydia trachomatis (AOR, 2.5; 95% CI, 1.1-5.8), and with a cervical or vaginal ulcer (AOR, 3.9; 95% CI, 2.1-7.4). HIV-1 shedding decreased from 42 to 21% (P < 0.005) in women whose STD were cured.

CONCLUSIONS

These data help to explain the difference in transmissibility between HIV-1 and HIV-2 and the increased infectiousness of HIV in the presence of immunosuppression and STD. In addition, they lend biological plausibility to arguments for making STD control an integral part of HIV prevention strategies in Africa.

HIV-2 genetic variation and DNA load in asymptomatic carriers and AIDS cases in Guinea-Bissau

The purpose of this study was to document which genetic subtypes of HIV-2 are present in Guinea-Bissau and to investigate whether asymptomatic HIV-2 carriers and AIDS patients carry distinct genetic variants. A secondary aim was to correlate proviral DNA load to clinical and immunologic status of the patients. Thirty-eight asymptomatic HIV-2 carriers and 11 AIDS patients from Bissau, Guinea-Bissau were included in a cross-sectional study in which HIV-2 env V3 sequences, HIV-2 DNA load, and CD4-positive (CD4+) lymphocyte counts were determined. Phylogenetic analyses showed that all investigated subjects carried subtype A HIV-2 variants and that the sequences from AIDS patients and asymptomatic carriers did not form distinct subclusters in the tree. As expected, patients with AIDS had significantly higher median HIV-2 DNA load than did asymptomatic carriers (4.6 vs. 2.0 log10 HIV-2 DNA copies/10(6) CD4+ lymphocytes). Our study indicates that the HIV-2 epidemic in Guinea-Bissau is almost exclusively caused by subtype A HIV-2 variants and that the HIV-2 infections among the asymptomatic carriers and AIDS cases included in the study do not have distinct epidemiologic histories.

9-year HIV-2-associated mortality in an urban community in Bissau, west Africa

BACKGROUND

Community studies with 1-3 years of follow-up have reported four to five times higher mortality in HIV-2-infected than in uninfected adults. In a cohort study of HIV-1, an increasing difference in mortality rates of HIV-1-infected and uninfected individuals is expected over time, because of rising mortality with advancing HIV-1 infection. We therefore investigated long-term survival of HIV-2-infected adults.

METHODS

Adults enrolled in 1987 in a community study of HIV-2 infection in Guinea-Bissau were followed up with serological surveys in 1989 and 1992. Survival was assessed in 1995, 9 years after enrollment.

FINDINGS

The annual incidence of HIV-2 was 0.7% for adults and tended to be higher for older individuals than for participants aged 15-44 years (relative risk 3.21 [95% CI 0.91-11.37]). With control for age, HIV-2-infected adults had twice as high mortality as uninfected individuals (mortality ratio 2.32 [1.18-4.57]); the mortality ratio was highest in the first year of the study (4.50 [1.31-15.43]). The difference between infected and uninfected individuals was stronger for adults under 45 years of age (mortality ratio 4.72 [1.86-11.97]) than for older people (1.35 [0.51-3.56]). HIV-2-infected individuals living with an infected spouse had significantly higher mortality than HIV-2-infected individuals living with an uninfected spouse (p = 0.027).

INTERPRETATION

HIV-2-associated mortality is not increasing with length of follow-up. Mortality in HIV-2-infected adults is only twice as high as that in uninfected individuals. In the majority of adults, HIV-2 has no effect on survival.

T-lymphocyte subsets in West African children: impact of age, sex, and season

OBJECTIVE

There has been no reference material for T-lymphocyte subsets for normal children in developing countries. We therefore used T-lymphocyte subset determinations among children in three different studies in Guinea-Bissau to construct age-related reference material and to examine possible determinants of T-lymphocyte subset levels.

METHODS

A total of 803 healthy West African children younger than 6 years were included in the three community studies of T-lymphocyte subsets among twins and singletons, after measles infection and after measles immunization. We used the immunoalkaline phosphatase method to determine T-lymphocyte subsets.

RESULTS

We found differences by age, sex, and season, whereas there were no significant differences by birth order, twinning, or ethnic group. The CD4+ percentage declined from birth to age 2 years, at which time it started to increase to higher levels at age 4 to 5 years. The CD8+ percentage increased gradually from early infancy to age 2 to 4 years. The leukocyte count peaked at age 12 to 23 months and declined thereafter, whereas the lymphocyte percentage peaked at age 1 to 5 months and declined gradually thereafter. Compared with dry-season results, the lymphocyte percentage, the absolute lymphocyte count, the absolute CD4+ T-lymphocyte count, and the CD4+/CD8+ ratio were significantly lower during the rainy season, whereas the CD8+ percentage was increased during the rainy season. Girls had higher CD4+/CD8+ ratios and lower CD8+ percentages than did boys.

CONCLUSIONS

Compared with the limited data on T-lymphocyte subsets available from healthy children in developed countries, Guinean children have markedly lower CD4+ percentages and CD4+/CD8+ ratios and higher lymphocyte percentages during the first 2 years of life, when the pressure of infections is particularly high in Africa.