Human immunodeficiency virus type 1 infection in homosexual men who remain seronegative for prolonged periods

Seronegative MSM at high risk of HIV-1 acquisition show an immune quiescent profile with a normal immune response against common antigens

Human immunodeficiency virus (HIV) infection still represents a major public health problem worldwide, and its vaccine remains elusive. The study of HIV-exposed seronegative individuals (HESN) brings important information about the natural resistance to HIV, allows a better understanding of the infection, and opens doors for new preventive and therapeutic strategies. Among HESN groups, there are some men who have sex with men (MSM) with high-risk sexual behaviors, who represent an adequate cohort for HESN study because of their major HIV exposure without infection. This study aimed to compare the immunological profile of Colombian seronegative MSM with different risk sexual behaviors. This study included 60 MSM at high-risk (n = 16) and low-risk (n = 44) of HIV-1 acquisition. No sex worker nor homozygous delta 32 mutation subjects were included. All participants were negative for anti-HIV-1/2 antibodies and HIV-1 proviral DNA. A higher frequency of sexual partners in the last 3 months before the study participation (median, 30 vs. 2), lifetime sexual partners (median, 1,708 vs. 26), and unprotected anal intercourse (median 12.5 vs. 2) was determined in high-risk MSM than low-risk MSM. High-risk MSM also showed a quiescent profile of T cells and natural killer (NK) cells, with a significantly lower percentage of CD4+CD38+, CD4+HLADR-CD38+, CD4+Ki67+ T cells, and NKG2D+ NK cells (CD3-CD16+CD56+), a significantly higher percentage of CD4+HLADR-CD38-, and a tendency to show a higher percentage of CD8+HLADR+CD38- T cells than the low-risk group. Likewise, they showed higher mRNA levels of Serpin A1 from PBMCs. The results suggest that this MSM cohort could be HESN individuals and their resistance would be explained by a quiescent profile of T cells and NK cells and an increased Serpin A1 expression. Further study on MSM at high risk of exposure to HIV-1 is necessary to better understand the natural resistance to HIV.

Sterol metabolism modulates susceptibility to HIV-1 Infection

BACKGROUND

25-hydroxylase (CH25H) is an interferon-stimulated gene (ISG), which catalyzes the synthesis of 25-hydroxycholesterol (25HC). 25HC intervenes in metabolic and infectious processes and controls cholesterol homeostasis and influences viral entry into host cells. We verified whether natural resistance to HIV-1 infection in HIV-1-exposed seronegative (HESN) individuals is at least partially mediated by particularities in sterol biosynthesis.

METHODS

Peripheral blood mononuclear cells (PBMCs) and monocyte-derived macrophages (MDMs) isolated from 15 sexually exposed HESN and 15 healthy controls were in vitro HIV-1-infected and analyzed for: percentage of IFNα-producing plasmacytoid dendritic cells (pDCs); cholesterol signaling and inflammatory response RNA expression; resistance to HIV-1 infection. MDMs from five healthy controls were in vitro HIV-1-infected in the absence/presence of exogenously added 25HC.

RESULTS

IFNα-producing pDCs were augmented in HESN compared with healthy controls both in unstimulated and in in vitro HIV-1-infected PBMCs (P < 0.001). An increased expression of CH25H and of a number of genes involved in cholesterol metabolism (ABCA1, ABCG1, CYP7B1, LXRα, OSBP, PPARγ, SCARB1) was observed as well; this, was associated with a reduced susceptibility to in-vitro HIV-1-infection of PBMCs and MDMs (P < 0.01). Notably, addition of 25HC to MDMs resulted in increased cholesterol efflux and augmented resistance to in-vitro HIV-1-infection.

CONCLUSION

Results herein show that in HESN sterol metabolism might be particularly efficient. This could be related to the activation of the IFNα pathway and results into a reduced susceptibility to in-vitro HIV-1 infection. These results suggest a possible basis for therapeutic interventions to modulate HIV-1 infection.

Genetic and epigenetic regulation of natural resistance to HIV-1 infection: new approaches to unveil the HESN secret

Introduction: Since the identification of HIV, several studies reported the unusual case of small groups of subjects showing natural resistance to HIV infection. These subjects are referred to as HIV-1-exposed seronegative (HESN) individuals and include people located in different areas, with diverse ethnic backgrounds and routes of exposure. The mechanism/s responsible for protection from infection in HESN individuals are basically indefinite and most likely are multifactorial.Areas covered: Host factors, including genetic background as well as natural and acquired immunity, have all been associated with this phenomenon. Recently, epigenetic factors have been investigated as possible determinants of reduced susceptibility to HIV infection. With the advent of the OMICS era, the availability of techniques such as GWAS, RNAseq, and exome-sequencing in both bulk cell populations and single cells will likely lead to great strides in the understanding of the HESN mystery.Expert opinion: The employment of increasingly sophisticated techniques is allowing the gathering of enormous amounts of data. The integration of such information will provide important hints that could lead to the identification of viral and host correlates of protection against HIV infection, allowing the development of more effective preventative and therapeutic regimens.

Genetic and immune determinants of immune activation in HIV-exposed seronegative individuals and their role in protection against HIV infection

Soon thereafter infection is established, hosts strive for an efficient eradication of microorganisms, with as limited tissue damage as possible, and durable immunological protection against re-infection. On the other hand, pathogens have developed countermeasures to escape host surveillance and to warrant diffusion to other hosts. In this molecular arms race the final results relies on multiple variables, including the genetic and immunologic e correlates of protection available for the host. In the field of HIV-infection, natural protection has been repeatedly associated to the presence of an immune activation state, at least in some cohorts of HESN (HIV-exposed seronegative). Indeed, these subjects, who naturally resist HIV-infection despite repeated exposure to the virus, are characterized by an increased expression of activation markers on circulating cells and greater production of immunological effector molecules both in basal condition and upon specific-stimulation. Although these results are not univocally shared, several publications emphasize the existence of a correlation between polymorphisms in genes associated with increased immune activation and the HESN phenotype. In this review, we will describe some of the genetic variants associated with protection against HIV infection. Understanding the basis of HIV resistance in HESN is mandatory to develop new preventative and therapeutic interventions.

Role of Different Subpopulations of CD8+ T Cells during HIV Exposure and Infection

During HIV infection, specific responses exhibited by CD8⁺ T cells are crucial to establish an early, effective, and sustained viral control, preventing severe immune alterations and organ dysfunction. Several CD8⁺ T cells subsets have been identified, exhibiting differences in terms of activation, functional profile, and ability to limit HIV replication. Some of the most important CD8⁺ T cells subsets associated with viral control, production of potent antiviral molecules, and strong polyfunctional responses include Th1-like cytokine pattern and Tc17 cells. In addition, the expression of specific activation markers has been also associated with a more effective response of CD8⁺ T cells, as evidenced in HLA-DR⁺ CD38⁻ cells. CD8⁺ T cells in both, peripheral blood and gut mucosa, are particularly important in individuals with a resistant phenotype, including HIV-exposed seronegative individuals (HESNs), long-term non-progressors (LTNPs) and HIV-controllers. Although the role of CD8⁺ T cells has been extensively explored in the context of an established HIV-1 infection, the presence of HIV-specific cells with effector abilities and a defined functional profile in HESNs, remain poorly understood. Here, we reviewed studies carried out on different subpopulations of CD8⁺ T cells in relation with natural resistance to HIV infection and progression.

Reevaluation of possible outcomes of infections with human immunodeficiency virus

Several lines of evidence indicate that HIV infection can result in several possible incomes, including a very small proportion of individuals whose HIV replication is controlled after treatment interruption (known as HIV posttreatment controllers) or spontaneously without any treatment (known as HIV elite controllers). Both types of individuals are HIV RNA negative but HIV DNA positive, with living virus which can be stimulated ex vivo. A review was conducted to assess the literature on yet rarer cases with detectable integrated HIV DNA without HIV infectious virus in HIV-seropositive or -negative individuals. Three categories of patients were identified: (a) HIV-seropositive individuals with apparent spontaneous cure from their HIV infection, (b) HIV-seronegative children born to HIV-infected mothers and (c) highly exposed seronegative adults. Validity criteria were proposed to assess the presence of integrated HIV DNA as possible or unquestionable in these three categories. Only three articles among the 22 ultimately selected fulfilled these criteria. Among the highly exposed seronegative subjects, some individuals were described as being without integrated HIV DNA, probably because these subjects were not investigated using relevant, highly sensitive methods. Finally, we propose a definition of spontaneous cure of HIV infection based on clinical, immunologic and virologic criteria.

Systems biology of the vervet monkey

Nonhuman primates (NHP) provide crucial biomedical model systems intermediate between rodents and humans. The vervet monkey (also called the African green monkey) is a widely used NHP model that has unique value for genetic and genomic investigations of traits relevant to human diseases. This article describes the phylogeny and population history of the vervet monkey and summarizes the use of both captive and wild vervet monkeys in biomedical research. It also discusses the effort of an international collaboration to develop the vervet monkey as the most comprehensively phenotypically and genomically characterized NHP, a process that will enable the scientific community to employ this model for systems biology investigations.

Regulatory variation in HIV-1 dependency factor ZNRD1 associates with host resistance to HIV-1 acquisition

BACKGROUND

ZNRD1 was identified as a host protein required for the completion of the human immunodeficiency virus (HIV) lifecycle in a genome-wide screen using small interfering RNA gene silencing. Subsequently, a genome-wide association study (GWAS) of host determinants for HIV-1 disease identified an association of single nucleotide polymorphisms (SNPs) in the ZNRD1 region with CD4(+) T-cell depletion.

METHODS

We investigated the effects of SNPs in the ZNRD1 region on human immunodeficiency virus type 1 (HIV-1) infection and progression to clinical outcomes in 5 US-based HIV-1 longitudinal cohorts consisting of men who have sex with men, males with hemophilia, and injection drug users (IDUs) (n = 1865). SNP function was evaluated by electrophoretic mobility shift assay and promoter luciferase assay.

RESULTS

A haplotype in the ZNRD1 gene showed significant association with a 35% decreased risk of HIV-1 acquisition (OR = 0.65, 95% CI, .47-.89), independent of HLA-C rs9264942, in European Americans. The SNP rs3132130 tagging this haplotype, located in the ZNRD1 5' upstream region, caused a loss of nuclear factor binding and decrease in ZNRD1 promoter activity. ZNRD1 variants also affected HIV-1 disease progression in European- and African-American cohorts.

CONCLUSIONS

This study provides novel evidence that ZNRD1 polymorphism may confer host resistance to HIV-1 acquisition.

Mucosal immunology of HIV infection

Recent advances in the immunology, pathogenesis, and prevention of human immunodeficiency virus (HIV) infection continue to reveal clues to the mechanisms involved in the progressive immunodeficiency attributed to infection, but more importantly have shed light on the correlates of immunity to infection and disease progression. HIV selectively infects, eliminates, and/or dysregulates several key cells of the human immune system, thwarting multiple arms of the host immune response, and inflicting severe damage to mucosal barriers, resulting in tissue infiltration of 'symbiotic' intestinal bacteria and viruses that essentially become opportunistic infections promoting systemic immune activation. This leads to activation and recruitment or more target cells for perpetuating HIV infection, resulting in persistent, high-level viral replication in lymphoid tissues, rapid evolution of resistant strains, and continued evasion of immune responses. However, vaccine studies and studies of spontaneous controllers are finally providing correlates of immunity from protection and disease progression, including virus-specific CD4(+) T-cell responses, binding anti-bodies, innate immune responses, and generation of antibodies with potent antibody-dependent cell-mediated cytotoxicity activity. Emerging correlates of immunity indicate that prevention of HIV infection may be possible through effective vaccine strategies that protect and stimulate key regulatory cells and immune responses in susceptible hosts. Furthermore, immune therapies specifically directed toward boosting specific aspects of the immune system may eventually lead to a cure for HIV-infected patients.

Mucosal correlates of protection in HIV-1-exposed sero-negative persons

Resistance to HIV-1 infection in HIV-1-exposed sero-negative (HESN) persons offers a promising opportunity to identify mechanisms of 'natural' protection. Unique features of the mucosa in particular may contribute to this protection. Here, we highlight several key issues pertaining to the mucosal correlates of protection in HESN persons, including humoral immune responses, mechanisms of mucosal HIV-1 neutralization, immune cell activation, and role of the microbiota in mucosal responses. We also discuss mucosal model systems that can be used to investigate the mechanisms of resistance in HESN subjects. A clear understanding of the mucosal correlates of protection against HIV-1 in HESN persons will provide critical new insights for the development of effective vaccine and microbicide strategies for the prevention of HIV-1 transmission.

Screening of HIV infection: role of molecular and immunological assays

Due to technical improvements and new developments of immunological assays, the reliability of serological laboratory diagnosis of HIV infection has improved considerably and the residual risk, due to the diagnostic window for transfusion-transmitted HIV, has been reduced significantly. Through the addition of nucleic acid amplification tests (NAT) to blood donor screening, the residual risk can de further decreased by up to 50%, depending on the sensitivity of the NAT protocol and whether individual or pooled blood donations are screened. In-house and commercially available NAT have been implemented in blood banks as HIV only or multiplexed HIV and hepatitis B or C virus assays. As an alternative to separate antigen and antibody screening, combined fourth-generation assays have been developed in 1997, and have achieved a high degree of sensitivity and specificity. Thus, they can replace stand-alone antigen and third-generation antibody assays. While they are used in the routine diagnostics of HIV infection in many countries throughout the world, they probably represent no alternative for NAT in blood-donor screening in industrialized countries. In the next few years, technical improvements will further simplify NAT screening. While there is still some potential to improve the detection threshold of NAT, the sensitivity of the antigen module of fourth-generation assays (a lowest concentration of 3-5 pg of p24 antigen) is probably very close to its technical limit.

The genetic basis of resistance to HIV infection and disease progression

Susceptibility to HIV infection and the modulation of disease progression are strictly dependent on inter-individual variability, much of which is secondary to host genetic heterogeneity. The study of host factors that control these phenomena relies not only on candidate gene approaches but also on unbiased genome-wide genetic and functional analyses. Additional new insights stem from the study of mechanisms that control the expression of host and viral genes, such as miRNA. The genetic host factors that have been suggested to be associated either with resistance to HIV-1 infection or with absent/delayed progression to AIDS are nevertheless unable to fully justify the phenomenon of differential susceptibility to HIV. Multidisciplinary approaches are needed to further analyze individuals who deviate from the expected response to HIV exposure/infection. Results of these analyses will facilitate the identification of novel targets that could be exploited in the setting up of innovative therapeutic or vaccine approaches.

Biological significance of soluble IL-2 receptor

A NUMBER of receptors for growth factors and differentiation antigens have been found to be secreted or released by cells. Following mononuclear cell (MNC) activation and interleukin-2 receptor (IL-2R) expression, a soluble form of the Alpha;-chain of IL-2R (sIL-2R) is released. The sIL-2R has been shown to be present in the culture supernatants of activated MNCs as well as in normal sera and, in higher amounts, in sera from subjects affected by several diseases including neoplastic, infectious and autoimmune ones, and in sera from transplanted patients suffering allograft rejection. The blood sIL-2R levels depend on the number of producing cells and the number of molecules per cell, so that sIL-2R blood values may represent an index of the number and the functional state of producing cells, both normal and neoplastic. Thus, monitoring of the immune system, mostly T-cells and haematological malignancies might be targets for the measurement of sIL-2R. Since many conditions may influence sIL-2R production, little diagnostic use may result from these measurements. However, since blood sIL-2R levels may correlate with disease progression and/or response to therapy, their measurement may be a useful index of activity and extent of disease. The precise biological role of the soluble form of the IL-2R is still a matter of debate. However, we know that increased sIL-2R levels may be observed in association with several immunological abnormalities and that sIL-2R is able to bind IL-2. It is conceivable then that in these conditions the excess sIL-2R released in vivo by activated lymphoid cells or by neoplastic cells may somehow regulate IL-2-dependent processes. On the other hand, it cannot exclude that sIL-2R is a by-product without biological significance. Finally, it is puzzling that in many conditions in which an increase of blood sIL-2R values has been observed, MNCs display a decreased in vitro capacity to produce sIL-2R. These seemingly contrasting findings are discussed in the light of the data showing that sIL-2R production correlates with IL-2 production.

Genetic correlates influencing immunopathogenesis of HIV infection

Variability to HIV infection, its progression as well as responsiveness to antiretroviral therapy (ART) is observed among individuals including viraemia controllers or exposed uninfected, rapid versus slow progressors and ART responders compared to non responders. This differential responsiveness/vulnerability to HIV-1 is governed by multiple host genetic factors that include HLA, cytokines, chemokines, their receptors and others. This review highlights the influence of these genetic factors on HIV/AIDS outcome; however, in India, the information in this area is very limited and most of these genetic studies have been conducted in Caucasian and South African populations. Considering, the population specific differences in the frequencies of protective or susceptibility favouring alleles and their influence on the disease outcome, it is of utmost importance to strengthen ongoing efforts towards defining largely unknown genetic propensity in Indian population, particularly by recruitment of large cohorts of well categorized exposed uninfected individuals, rapid, long term non progressors and elite viraemic controllers. Multi-parametric analysis of these potentially interactive immunogenetic variables in these cohorts may help to define potential targets for diagnostics and therapy in a population specific manner.

Sensitive and specific target sequences selected from retrotransposons of Schistosoma japonicum for the diagnosis of schistosomiasis

BACKGROUND

Schistosomiasis japonica is a serious debilitating and sometimes fatal disease. Accurate diagnostic tests play a key role in patient management and control of the disease. However, currently available diagnostic methods are not ideal, and the detection of the parasite DNA in blood samples has turned out to be one of the most promising tools for the diagnosis of schistosomiasis. In our previous investigations, a 230-bp sequence from the highly repetitive retrotransposon SjR2 was identified and it showed high sensitivity and specificity for detecting Schistosoma japonicum DNA in the sera of rabbit model and patients. Recently, 29 retrotransposons were found in S. japonicum genome by our group. The present study highlighted the key factors for selecting a new perspective sensitive target DNA sequence for the diagnosis of schistosomiasis, which can serve as example for other parasitic pathogens.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we demonstrated that the key factors based on the bioinformatic analysis for selecting target sequence are the higher genome proportion, repetitive complete copies and partial copies, and active ESTs than the others in the chromosome genome. New primers based on 25 novel retrotransposons and SjR2 were designed and their sensitivity and specificity for detecting S. japonicum DNA were compared. The results showed that a new 303-bp sequence from non-long terminal repeat (LTR) retrotransposon (SjCHGCS19) had high sensitivity and specificity. The 303-bp target sequence was amplified from the sera of rabbit model at 3 d post-infection by nested-PCR and it became negative at 17 weeks post-treatment. Furthermore, the percentage sensitivity of the nested-PCR was 97.67% in 43 serum samples of S. japonicum-infected patients.

CONCLUSIONS/SIGNIFICANCE

Our findings highlighted the key factors based on the bioinformatic analysis for selecting target sequence from S. japonicum genome, which provide basis for establishing powerful molecular diagnostic techniques that can be used for monitoring early infection and therapy efficacy to support schistosomiasis control programs.

The multicenter AIDS Cohort Study, 1983 to …

The Multicenter AIDS Cohort (MACS), initiated in 1983 at the Johns Hopkins School of Public Health, the University of Pittsburgh School of Public Health, Northwestern University School of Medicine, and the UCLA School of Public Health, continues to conduct studies and publish key papers on the natural history of untreated and treated HIV infection in 6972 men-who-have-sex-with-men. Through May 2011, 1,490,995 specimens have been collected, 86,883 person-years of data accrued and 1195 scientific papers published in international journals.

Outcomes of a National Institute of Allergy and Infectious Diseases Workshop on understanding HIV-exposed but seronegative individuals

The fascinating conundrum that some individuals who are exposed to HIV in ways that would make viral transmission highly likely, yet are able to remain uninfected, has been appreciated for many years. As early as the late 1980s, reports of such individuals began appearing in the HIV/AIDS literature. Despite the critical importance of understanding possible mechanisms of natural HIV resistance for developing effective prevention strategies, numerous obstacles have prevented this essential area of scientific exploration from moving forward. The Workshop held on July 8-9, 2010 and supported by the Office of AIDS Research (OAR), the National Institute of Allergy and Infectious Diseases (NIAID), and the National Institute on Drug Abuse (NIDA) at the NIH hosted 200 participants and utilized the expertise of 42 AIDS researchers as invited speakers, session chairs, and discussion leaders for presentations and breakout sessions in an attempt to remove some of those obstacles. Accomplishments of the participants included developing a consensus for a new general term for the field, HIV-exposed seronegative (HESN), while recognizing the necessity to identify and utilize secondary descriptive criteria such as exposure level, risk group, duration of seronegativity, or natural resistance. Three key questions for future research were also identified by the group: (1) What is different in HESN versus those who get infected? (2) What is the immune response in HESN and is it just a marker of exposure or a correlate of protection? (3) What are the HESN host factors that help HESN resist infection? This report briefly summarizes the presentations, and describes future directions for addressing these questions and challenges.

Absence of reproducibly detectable low-level HIV viremia in highly exposed seronegative men and women

OBJECTIVE

Transient HIV infections have been invoked to account for the cellular immune responses detected in highly virus-exposed individuals who have remained HIV-seronegative. We tested for very low levels of HIV RNA in 524 seronegative plasma samples from 311 highly exposed women and men from three longitudinal HIV cohorts.

DESIGN

Two thousand and seventy-three transcription-mediated amplification (TMA) HIV RNA tests were performed for an average of 3.95 TMA assays per plasma sample. Quadruplicate TMA assays, analyzing a total of 2 ml of plasma, provided an estimated sensitivity of 3.5 HIV RNA copies/ml.

RESULTS

Four samples from individuals who did not seroconvert within the following 6 months were positive for HIV RNA. For one sample, human polymorphism DNA analysis indicated a sample mix-up. Borderline HIV RNA detection signals were detected for the other three positive samples but further replicate TMA testing yielded no positive results. Nested PCR assays (n = 254) for HIV proviral DNA in peripheral blood mononuclear cells (PBMCs) from these three individuals were negative.

CONCLUSION

Transient viremia was not reproducibly detected in highly HIV-exposed seronegative men and women. If transient infections do occur, plasma HIV RNA levels may remain below the detection limits of the sensitive assay used here, be of very short duration, or viral replication may be restricted to mucosal surfaces or their draining lymphoid tissues.

Preinfection human immunodeficiency virus (HIV)-specific cytotoxic T lymphocytes failed to prevent HIV type 1 infection from strains genetically unrelated to viruses in long-term exposed partners

Understanding the mechanisms underlying potential altered susceptibility to human immunodeficiency virus type 1 (HIV-1) infection in highly exposed seronegative (ES) individuals and the later clinical consequences of breakthrough infection can provide insight into strategies to control HIV-1 with an effective vaccine. From our Seattle ES cohort, we identified one individual (LSC63) who seroconverted after over 2 years of repeated unprotected sexual contact with his HIV-1-infected partner (P63) and other sexual partners of unknown HIV-1 serostatus. The HIV-1 variants infecting LSC63 were genetically unrelated to those sequenced from P63. This may not be surprising, since viral load measurements in P63 were repeatedly below 50 copies/ml, making him an unlikely transmitter. However, broad HIV-1-specific cytotoxic T-lymphocyte (CTL) responses were detected in LSC63 before seroconversion. Compared to those detected after seroconversion, these responses were of lower magnitude and half of them targeted different regions of the viral proteome. Strong HLA-B27-restricted CTLs, which have been associated with disease control, were detected in LSC63 after but not before seroconversion. Furthermore, for the majority of the protein-coding regions of the HIV-1 variants in LSC63 (except gp41, nef, and the 3' half of pol), the genetic distances between the infecting viruses and the viruses to which he was exposed through P63 (termed the exposed virus) were comparable to the distances between random subtype B HIV-1 sequences and the exposed viruses. These results suggest that broad preinfection immune responses were not able to prevent the acquisition of HIV-1 infection in LSC63, even though the infecting viruses were not particularly distant from the viruses that may have elicited these responses.

The search for protection against HIV infection

More than 25 years after the recognition of AIDS and the isolation of the causative agent, human immunodeficiency virus (HIV), we have been unable to develop a vaccine to protect against infection. The major obstacle to development of a vaccine has been the absence of naturally acquired protective immunity, which is characteristic of most infectious agents. We and others, however, have identified individuals who appear to be resistant to infection. Using a combination of epidemiology, molecular biology, and genetics, we hypothesize that these individuals are able to resist infection by clearing low doses of HIV from their systems. We further hypothesize that they are able to clear the virus through a highly efficient system of processing and presentation of HIV epitopes (antigens) to CD8+ cytotoxic cells, which activate them to remove virally infected cells. Subsequent studies have lent support to this hypothesis.

Serodeconversion of HIV antibody-positive AIDS patients following treatment with V-1 Immunitor

It is extremely rare when HIV seropositive adult patients experience spontaneous loss of antibodies, that is, seroreversion. The disappearance of HIV antibodies was occasionally attributed to iatrogenic intervention—serodeconversion. Such interventions include: HAART; oral interferon; Chinese herbal remedies; and therapeutic AIDS vaccines derived from pooled blood. Oral therapeutic, alloimmune AIDS vaccine, V-1 Immunitor (V1), was administered to 60000 HIV-positive Thai patients. The administration of V1 resulted in serodeconversion among 23 individuals. The patient group consisted of 9 females (39%) and 14 males (61%) including two 2-year-old boys. The age range was 2–58 years with mean/median 29/29.3 years. Patients were tested seropositive for HIV at least once before being enrolled on V1. The duration of treatment until discovery of seronegative status ranged between 2 weeks and 15 months with average/median 7.2/8 months. Time to seronegativity was correlated with baseline disease stage (R = 0.62; P = .002). The seronegative status was positively associated with V1-induced undetectable or low viral load (R = 0.65; P = .0008). The odds ratio analysis comparing the outcome of our study with published surveys of diagnostic accuracy of laboratory tests suggested that the probability of HIV antibody testing error was remote (P < .000001). The possible causes responsible for this unusual phenomenon are discussed.

Early depletion of proliferating B cells of germinal center in rapidly progressive simian immunodeficiency virus infection

Lack of virus specific antibody response is commonly observed in both HIV-1-infected humans and SIV-infected monkeys with rapid disease progression. However, the mechanisms underlying this important observation still remain unclear. In a titration study of a SIVmac239 viral stock, three out of six animals with viral inoculation rapidly progressed to AIDS within 5 months. Unexpectedly, there was no obvious depletion of CD4(+) T cells in both peripheral and lymph node (LN) compartments in these animals. Instead, progressive depletion of proliferating B cells and disruption of the follicular dendritic cell (FDC) network in germinal centers (GC) was evident in the samples collected at as early as 20 days after viral challenge. This coincided with undetectable, or weak and transient, virus-specific antibody responses over the course of infection. In situ hybridization of SIV RNA in the LN samples revealed a high frequency of SIV productively infected cells and large amounts of accumulated viral RNA in the GCs in these animals. Early severe depletion of GC proliferating B cells and disruption of the FDC network may thus result in an inability to mount a virus-specific antibody response in rapid progressors, which has been shown to contribute to accelerated disease progression of SIV infection.

Surveillance of risk profiles among new and repeat blood donors with transfusion-transmissible infections from 1995 through 2003 in the Netherlands

BACKGROUND

To evaluate the effectiveness of blood donor selection, this study reports risk profiles of donors with transfusion-transmissible infections as obtained by ongoing surveillance, 1995 through 2003, in the Netherlands.

STUDY DESIGN AND METHODS

A surveillance program was installed to monitor risk profiles among new and repeat donors infected with human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B virus (HBV), or human T-lymphotropic virus (HTLV), or positive for the presence of syphilis antibodies. At posttest counseling, a physician interviewed donors to clarify possible sources of infection.

RESULTS

A total of 167 repeat donors and 404 new donors were interviewed: 33 with HIV, 123 with HCV, 279 with HBV, 21 with HTLV, and 112 with syphilis antibodies. Most HBV, HCV, and HTLV infections were among new donors (80, 85, and 67%), whereas most HIV infections were among repeat donors (79%). Nearly 25 percent of the donors did not report factors at screening that would have deferred them from donating blood. At posttest interviews, new donors with HCV often reported injecting drug use (19%). Repeat donors with HIV often reported male-to-male sex (8/26, 31%).

CONCLUSION

A significant level of deferrable behavioral risks was found among donors with confirmed transfusion-transmissible infections that persist despite current donor selection. Reporting such behavior at initial donor selection would have eliminated a substantial part of the infections found. This study argues against relaxing the existing donor deferral of persons practicing male-to-male sex, given their significant proportion of HIV infections among repeat donors. Systematic surveillance of risk factors among infected blood donors provides ongoing information about the effectivity of donor selection and is recommended to evaluate and optimize blood policies.

Early detection of Schistosoma mansoni infection by touchdown PCR in a mouse model

A detection assay for Schistosoma mansoni DNA in mouse serum samples based on touchdown PCR was developed and evaluated. The serum samples could be assayed directly without the need to extract DNA. No cross reactions between S. mansoni and related species inducing human schistosomiasis were observed. After the infection, mouse sera and feces were collected for 8 weeks. Anti-worm antigen IgG and anti-soluble egg antigen IgG were detected in the sera at 6 weeks post-infection by ELISA. The parasite's eggs were detected in the feces at 8 weeks. In contrast, S. mansoni DNA was detected in the sera at 2 weeks post-infection. These data suggest that touchdown PCR is a potential tool for the early diagnosis of S. mansoni infection.

Transient or occult HIV infections may occur more frequently than progressive infections: changing the paradigm about HIV persistence

Evidence of transient HIV infections was found in 8 subjects at high-risk for HIV infection among 47 longitudinally studied over 2-5 (average approximately 3.5) years, whereas only two subjects developed progressive infection. All of these subjects developed serum antibodies (Ab) to conformational epitopes of HIV gp41 (termed "early HIV Ab"), but the 8 transiently infected subjects lost this Ab within 4-18 months, and did not seroconvert to positivity in denatured antigen EIA or Western Blot (WB). However, the two progressively infected subjects eventually seroconverted in the EIA and WB tests within one to two months after the appearance of "early HIV Ab". HIV env and nef sequences were directly PCR amplified from the peripheral blood mononuclear cells (PBMCs) of two of the eight transiently infected subjects during the time of "early HIV Ab"-postivity, and these showed significant sequence divergence from the HIV strains in the laboratory, indicating that they were not laboratory contaminants. Genome identity typing ("paternity-typing") of PBMC samples obtained at the time of "early HIV Ab"-positivity, and later when Ab was absent from each of the 8 subjects, showed that blood samples were not mixed-up. This provides further evidence that transient or occult infection with HIV does occur, and perhaps at a greater frequency than do progressive infections.

Global human genetics of HIV-1 infection and China

Genetic polymorphisms in human genes can influence the risk for HIV-1 infection and disease progression, although the reported effects of these alleles have been inconsistent. This review highlights the recent discoveries on global and Chinese genetic polymorphisms and their association with HIV-1 transmission and disease progression.

Topographic and quantitative display of integrated human immunodeficiency virus-1 provirus DNA in human lymph nodes by real-time polymerase chain reaction

In situ polymerase chain reaction (isPCR) has been applied in many fields that require detection of a genomic marker in combination with its topographic localization in tissue. We describe here a novel approach that circumvents the major drawbacks of in situ PCR, ie, low sensitivity, leakage of DNA from cells, and inability to quantify the DNA input. Frozen sections of a lymph node from a human immunodeficiency virus (HIV)-1-infected patient were fixed on glass microscope slides, and the glass was scored into square fragments of 0.5-mm edge length using a diamond cutting device. Slides were then attached to adhesive, elastic plastic foil and finally broken, and the foil was extended to allow sorting of fragments into PCR microtiter plates. The material was tested for HIV-1 proviral DNA by a sensitive real-time PCR protocol. Subjacent sections were stained for follicular dendritic cells to identify follicles. The fragmentation process prevented leakage of amplified DNA to neighboring areas as often experienced with in situ PCR. Provirus was clearly associated with follicular areas, in which provirus-carrying cells represented an average of 0.8% of the total cell population (peak density, 3.1% of all follicular cells). The results of this method suggest that the high density of provirus-containing cells in follicles may be important for the persistence of proviral DNA in infected persons.

Low levels of human immunodeficiency virus type 1 DNA in high-risk seronegative men

We detected human immunodeficiency virus type 1 (HIV-1) DNA at very low levels in sequential peripheral blood mononuclear cell samples of five out of six high-risk, seronegative, homosexual men and five out of five individuals 7.8 to 1.6 years prior to seroconversion. These data indicate a high prevalence of low-level HIV-1 DNA in exposed seronegative individuals.

Assays for HIV with improved sensitivity and specificity

Increased knowledge of the human immunodeficiency virus (HIV) and the infection it causes in humans has resulted in an enormous expansion in the understanding of viral parameters and host changes. HIV is a virus which mutates readily and rapidly, presenting many challenges to assay developers, and monitors of therapy and drug-resistance. Prolific viral replication at all the stages of the disease means that an accurate assessment of viral burden, viral load and changes to immune system markers is essential for effective clinical management and treatment. In the present review we have summarised current opinion on the kinetics of HIV infection and the pathogenesis of the disease it causes, and have provided a background to the evolution of HIV assays. Sensitivities and specificities of assays used for anti-HIV and HIV detection have improved, and new assays have been developed employing novel molecular techniques, which are being applied to meet continually evolving demands for more sensitive measurement of an increasing number of parameters. The future of HIV testing is also considered in the light of new knowledge concerning virus dynamics in vivo, the likelihood of the emergence of new subtypes and the changing approach to therapy. Assays will be, on the whole, used to quantify virus and to measure the host reactions to infection, often in the presence of antivirals. Thus, extreme sensitivity and specificity will be required.

Persistence of low levels of simian immunodeficiency virus in macaques that were transiently viremic by conventional testing

Transient SIV viremia after experimental SIV challenge has been documented. Whether SIV persists in these transiently viremic macaques remains unclear. In the present study, we applied a sensitive PCR and found persistent low levels of SIVmne infection (LLSI) (range: 0.1-5.3 SIV DNA copies/10(6) PBMC) in seven macaques that were transiently positive by conventional assays, which was 10(2)- to 10(6)-fold less than those of SIVmne infected monkeys with typical disease progression. SIV envelope V1 sequences remained homogeneous in these macaques for the 6-year study period, with a mean evolution rate of 0.005% per site per year, which was not different from zero (P = 0.612) and significantly lower than that (0.56-1.18%) in macaques with progressive infection of SIVmne. LLSI macaques have remained free from SIV-associated illness, and are still alive 10 years after virus inoculation. Understanding the mechanisms underlying this outcome may provide valuable insight into therapy and vaccine development.

Persistent alterations in the T-cell repertoires of HIV-1-infected and at-risk uninfected men

OBJECTIVE

We examined the association between immunogenic exposure and T-cell receptor (TCR) diversity to more clearly assess the impact of HIV-1 infection on the T-cell repertoire.

METHODS

: To estimate the extent of T-cell clonality attributable to HIV-1 infection, we evaluated T-cell repertoires in low-risk and at-risk seronegative men and HIV-1 seropositive men by assessment of T-cell receptor beta-chain (TCR beta) complimentary determining region 3 (CDR3) lengths.

RESULTS

The frequency of T-cell clonality in both HIV-1 infected and at-risk uninfected men was elevated in comparison to low-risk uninfected men. Among low-risk and at-risk seronegative, and HIV-1 seropositive men, clonal expansions were present in 3, 8, and 10% of CD4+ CDR3 lengths, and 18, 22, and 28% of CD8+ CDR3 lengths respectively. In addition, the longitudinal conservation of clonal expansions was observed in at-risk seronegative men. Based on comparisons to at-risk seronegative men, we estimate that at-risk seropositive men with chronic HIV-1 infection exhibit a 27% increase in the number of expanded CD8+ CDR3 lengths.

CONCLUSION

These findings provide an approximation of the magnitude of the T-cell response in individuals undergoing chronic HIV-1 infection and demonstrate a significant association between the history of immunogenic challenge and the magnitude of clonality within the T-cell repertoire. In addition, these findings underscore the necessity of selecting controls with similar antigenic exposure histories when investigating T-cell dynamics in HIV-infected individuals.

Persistence of extraordinarily low levels of genetically homogeneous human immunodeficiency virus type 1 in exposed seronegative individuals

Some individuals remain inexplicably seronegative and lack evidence for human immunodeficiency virus type 1 (HIV-1) infection by conventional serologic or virologic testing despite repeated high-risk virus exposures. Here, we examined 10 exposed seronegative (ES) individuals exhibiting HIV-1-specific cytotoxicity for the presence of HIV-1. We discovered HIV-1 DNA in resting CD4(+) T cells (mean, 0.05 +/- 0.01 copies per million cells) at multiple visits spanning 69 to 130 weeks in two ES individuals at levels that were on average 10(4)- to 10(6)-fold lower than those of other HIV-1-infected populations reported. Sequences of HIV-1 envelope and gag genes remained markedly homogeneous, indicating little to undetectable virus replication. These results provide the evidence for HIV-1 infection in ES individuals below the detection limit of standard assays, suggesting that extraordinary control of infection can occur. The two HIV-infected ES individuals remained healthy and were not superinfected with other HIV-1 strains despite continued high-risk sexual exposures to multiple HIV-infected partners. Understanding the mechanisms that confer diminished replicative capacity of HIV-1 in these hosts is paramount to developing strategies for protection against and control of HIV-1 infection.

A new improved method for the concentration of HIV-1 infective particles

Improvement of the sensitivity of detection systems for human immunodeficiency virus-1 (HIV-1) has been carried out. One approach to improve the sensitivity is purification and/or concentration of the virus from a specimen. In this study, a method for concentrating HIV-1 using polyethylene glycol (PEG) has been re-evaluated and the optimal protocol for concentrating the virus from low-titer specimens was determined. That is, to obtain a virus pellet, a mixture of equal volumes of a specimen and 20% PEG 20,000 solution in saline is incubated at 4 degrees C for 16 h and then centrifuged at 17860 x g in a microcentrifuge for 20 min. HIV-1 in the pellet could be detectable by HIV-1 p24 antigen capture assay for viral protein, reverse transcriptase (RT) assay for viral enzyme, reverse transcriptase polymerase chain reaction (RT-PCR) assay for viral RNA and a virus infectivity assay.

Immunologic profile of highly exposed yet HIV type 1-seronegative men

The host immune factors that determine susceptibility to HIV-1 infection are poorly understood. We compared multiple immunologic parameters in three groups of HIV-1-seronegative men: 14 highly exposed (HR10), 7 previously reported possibly to have sustained transient infection (PTI), and a control group of 14 low risk blood bank donors (BB). Virus-specific cellular immune assays were performed for CD4(+) T helper cell responses, CD8(+) cytotoxic T lymphocyte activity, CD8(+) cell chemokine release, and CD8(+) cell-derived antiviral soluble factor activity. General immune parameters evaluated included CCR5 genotype and phenotype, interferon alpha production by PBMCs, leukocyte subset analysis, and detailed T lymphocyte phenotyping. Comparisons revealed no detectable group-specific differences in measures of virus-specific immunity. However, the HR10 group differed from the BB group in several general immune parameters, having higher absolute monocyte counts, higher absolute CD8(+) T cell counts and percentages, lower naive and higher terminal effector CD8(+) cells, and lower levels of CD28(+)CD8(+) cells. These changes were not associated with seropositivity for other chronic viral infections. The PTI men appeared to have normal levels of monocytes and slightly elevated levels of CD8(+) T cells (also with increased effector and decreased naive cells). Although we cannot entirely exclude the contribution of other chronic viral infections, these findings suggest that long-lived systemic cellular antiviral immunity as detected by our assays is not a common mechanism for resistance to infection, and that resistance may be multifactorial. General immune parameters reflected by CD8(+) T cell levels and activation, and monocyte concentrations may affect the risk of infection with HIV-1, and/or serve as markers of exposure.

Chemokine RANTES promoter polymorphism affects risk of both HIV infection and disease progression in the Multicenter AIDS Cohort Study

OBJECTIVE

To examine whether polymorphism in the RANTES gene is associated with HIV disease outcome.

DESIGN

RANTES, a ligand of the major HIV co-receptor, CCR5, is known to block HIV-CCR5 interactions. Recently, two single nucleotide polymorphisms in the RANTES gene promoter region, designated -403G/A and -28C/G, have been described. Both polymorphisms can affect in-vitro promoter activity, and the RANTES -403A, -28G haplotype has been associated with a slower CD4 cell count decline rate in a Japanese cohort.

METHODS

We compared RANTES compound genotype frequencies between HIV-positive and exposed-uninfected participants of the Multicenter AIDS Cohort Study (MACS) and rates of progression to AIDS for MACS seroconverters.

RESULTS

We found that the two most common RANTES promoter compound genotypes, G1 (-403G/G, -28C/C) found in 67% of Caucasians, and G4 (-403G/A, -28C/C) found in 23% of Caucasians, were associated with altered risk of HIV transmission and progression, particularly in individuals who lacked the protective CCR5 mutation, CCR5delta32. In this study, individuals with a G4 compound genotype were more likely to acquire HIV than individuals with a G1 compound genotype (OR 1.72, P = 0.016) and the risk increased when individuals possessing CCR5delta32 were omitted from consideration (OR 2.13, P = 0.005). Among seroconverters lacking CCR5delta32, those who had the G4 compound genotype progressed significantly slower to AIDS-1993 than those with the G1 compound genotype (median time to AIDS 7.6 versus 5.4 years; RH 0.65; P = 0.007).

CONCLUSIONS

These data implicate the RANTES-403A allele as a risk factor for HIV transmission and as a protective factor for HIV progression.

Feline immunodeficiency virus clade C mucosal transmission and disease courses

The transmissibility and pathogenicity of a clade C feline immunodeficiency virus (FIV-C) was examined via the oral-nasal, vaginal, or rectal mucosa. FIV-C was transmissible by all three mucosal routes. Vaginal transmission was most efficient (100%), oral exposure resulted in a 80% infection rate, and rectal transmission was least effective (44%). In contrast to previous intravenous passage studies, a broader range of host-virus relationships was observed after mucosal exposure. Three categories of FIV-C infection were defined: (1) rapidly progressive infection marked by high virus burdens and rapid CD4+ cell depletion (43% of vaginally exposed animals); (2) conventional (typical) infection featuring slowly progressive CD4+ cell decline (61% of all exposed animals); and (3) regressive (transient) infection marked by low and then barely detectable virus burdens and no CD4+ cell alterations (22% of rectally inoculated cats). These disease courses appear to have parallels in mucosal HIV and SIV infections, emphasizing the importance of the virus-mucosa interface in lentiviral pathogenesis.

HIV and the returning expatriate

Worldwide seroprevalence of the Human Immunodeficiency Virus (HIV) was estimated at 29.4 million at the end of 1996 with 75-85% of infections in adults transmitted through sexual intercourse, and by heterosexual intercourse in more then 70%. SubSaharan Africa is currently the area most heavily affected but over the past 5 years rapid spread of the virus has occurred in Asia. No developing country is free of HIV infection and HIV infection acquired abroad now accounts for most of heterosexually acquired HIV infection presenting in the (United Kingdom) UK, accounting for 25% of new HIV cases in the UK in the year to end March 1995 and 18% in the year to end March 1996, and at least 38% of new cases in Scotland in 1996.

Occult systemic infection and persistent simian immunodeficiency virus (SIV)-specific CD4(+)-T-cell proliferative responses in rhesus macaques that were transiently viremic after intravaginal inoculation of SIV

The intact cervicovaginal mucosa is a relative barrier to the sexual transmission of human immunodeficiency virus type 1 (HIV-1). In the simian immunodeficiency virus (SIV) macaque model of HIV infection, seronegative transient viremia (STV; virus isolation positive followed by repeated negative cultures) occurs after intravaginal inoculation of a low dose of pathogenic SIVmac251 (C. J. Miller, M. Marthas, J. Torten, N. Alexander, J. Moore, G. Doncel, and A. Hendrickx, J. Virol. 68:6391-6400, 1994). Thirty-one adult female macaques that had been inoculated intravaginally with pathogenic SIVmac251 became transiently viremic. One monkey that had been culture negative for a year after SIV inoculation became persistently viremic and developed simian AIDS. No other STV monkey developed persistent viremia or disease. Results of very sensitive assays showed that 6 of 31 monkeys had weak SIV-specific antibody responses. SIV-specific antibodies were not detected in the cervicovaginal secretions of 10 STV monkeys examined. Twenty of 26 monkeys had lymphocyte proliferative responses to p55(gag) and/or gp130(env) antigens; 3 of 6 animals, including the monkey that became persistently viremic, had detectable cytotoxic T-lymphocyte (CTL) responses to SIV. At necropsy, lymphoid tissues and vaginal mucosa were virus culture negative, but in 10 of 10 animals, SIV provirus was detected by PCR using gag-specific primer pairs. Fifty percent of the PCR-positive tissue samples were also positive for SIV gag RNA by reverse transcriptase PCR. Thus, transient viremia following intravaginal inoculation of pathogenic SIV is associated with persistent, systemic infection, either latent or very low level productive. Atypical immune responses, characterized by lymphocyte proliferation and some CTL responses in the absence of conventionally detectable antibodies, develop in transiently viremic monkeys.

Evaluation of epidemiological and serological predictors of human immunodeficiency virus type-1 (HIV-1) infection among high risk professional blood donors with western blot indeterminate results

BACKGROUND

Indeterminate pattern of results in Western blot (WBI) for human immunodeficiency virus type-1 (HIV-1) infection may represent early HIV-1 infection or may be non-specific in origin. This issue can be resolved by follow up testing upto at least 6 months resulting in psychological distress as well as in high drop out rates among those undergoing investigation pointing out the need for additional parameters that could help in determining the status of HIV-1 infection at the time of initial testing itself in individuals with WBI pattern.

OBJECTIVE

The objectives of the present study were: (i) to determine the frequency of HIV-1 infected individuals in a group of professional donors showing WBI patterns in initial testing on the basis of follow up serological studies; (ii) to find out if any HIV related epidemiological or serological characteristics recorded at the time of initial testing could be considered as predictor for HIV-1 infection in WBI specimens; and (iii) to evaluate two alternative serodiagnostic strategies for HIV-1 infection viz. multiple EIAs based on different antigen preparations/principles and a line immunoassay (LIA) employing recombinant antigens in resolving status of HIV-1 infection in specimens showing WBI results at initial testing.

STUDY DESIGN

Professional donors with WBI patterns belonging to EIA reactive and EIA nonreactive groups were subjected to study of epidemiological profile, prevalence of sexually transmitted diseases (STD) markers and follow up serological testing for HIV-1 at 6, 12, 24 and 48 weeks intervals to record any seroconversion. The initial and follow up specimens from the donors with initial WBI results were subjected to two EIAs (one based on dot immunoassay using synthetic HIV-1 antigens and other based on microwell EIA using recombinant HIV-1 proteins) as well as to LIA.

RESULTS

Professional donors with initial WBI results, from the EIA reactive group had higher proportion of unmarried individuals (90.3%), with history of heterosexual promiscuity (75%) and visit to STD clinics (36.1%) compared with the WBI donors from the EIA nonreactive group (72.7, 42.4 and 12.1%, respectively, P values < 0.001). Prevalence of antitreponemal antibodies was higher in the former group (16.7%) compared with the later group (1.5%, P value < 0.002). Seroconversion was recorded in 4 (7.3%) out of 55 EIA reactive WBI donors from the EIA reactive group that were characterised by high optical density (OD) values in EIA, 'p24 only' pattern of band in WB and positivity by LIA at the time of initial testing. LIA was found to be more reliable test compared with combination of EIAs to determine status of HIV-1 infection in WBI specimens at the time of initial testing.

CONCLUSION

The present study points out that parameters like history of heterosexual promiscuity, prevalence of STD markers, high OD values in screening EIA, 'p24' only pattern of bands in WB and positivity by LIA could have individual predictive values for HIV-1 infection in specimens showing WBI pattern of results at initial testing.

[Molecular biology and transfusional viral safety]

In this review we present four fields to which viral molecular biology has contributed: the discovery of blood-borne viruses and the knowledge of the natural history of infection by these viruses; the validation of the results of virological assays used in the biological screening of blood donations; the contribution of molecular biology in inquiries into viral transfusional contamination; the interest of molecular biology in viral transfusional epidemiology. We subsequently deal with the parameters of the discussion on the impact and the feasibility of a systematic screening of several viral genomes in blood donations.