Human immunodeficiency virus type 1 bound to B cells: relationship to virus replicating in CD4+ T cells and circulating in plasma

The molecular mechanisms of virus-induced human cancers

Cancer is a serious public health problem globally. Many human cancers are induced by viruses. Understanding of the mechanisms by which oncogenic (tumorigenic) viruses induce cancer is essential in the prevention and control of cancer. This review covers comprehensive characteristics and molecular mechanisms of the main virus-attributed cancers caused by human papillomavirus, hepatitis B virus, hepatitis C virus, Epstein-Barr virus, human herpesvirus type 8, human T-cell lymphotropic virus, human polyomaviruses, Merkel cell polyomavirus, and HIV. Oncogenic viruses employ biological processes to replicate and avoid detection by host cell immune systems. Tumorigenic infectious agents activate oncogenes in a variety of ways, allowing the pathogen to block host tumour suppressor proteins, inhibit apoptosis, enhance cell proliferation, and promote invasion of host cells. Furthermore, this review assesses many pathways of viruses linked to cancer, including host cellular communication perturbation, DNA damage mechanisms, immunity, and microRNA targets that promote the beginning and progression of cancer. The current cancer prevention is primarily focused on non-communicable diseases, but infection-attributable cancer also needs attention to significantly reduce the rising cancer burden and related deaths.

Simian Immunodeficiency Virus Susceptibility, Immunology, and Microbiome in the Female Genital Tract of Adolescent Versus Adult Pigtail Macaques

In Sub-Saharan Africa, young women 15-24 years of age account for nearly 30% of all new HIV infections, however, biological and epidemiological factors underlying this disproportionate infection rate are unclear. In this study, we assessed biological contributors of SIV/HIV susceptibility in the female genital tract (FGT) using adolescent (n = 9) and adult (n = 10) pigtail macaques (PTMs) with weekly low-dose intravaginal challenges of SIV. Immunological variables were captured in vaginal tissue of PTMs by flow cytometry and cytokine assays. Vaginal biopsies were profiled by proteomic analysis. The vaginal microbiome was assessed by 16S rRNA sequencing. We were powered to detect a 2.2-fold increase in infection rates between age groups, however, we identified no significant differences in susceptibility. This model cannot capture epidemiological factors or may not best represent biological differences of HIV susceptibility. No immune cell subsets measured were significantly different between groups. Inflammatory marker MCP-1 was significantly higher (adj p = .02), and sCD40L trended higher (adj p = .06) in vaginal cytobrushes of adults. Proteomic analysis of vaginal biopsies showed no significant (adj p < .05) protein or pathway differences between groups. Vaginal microbiomes were not significantly different between groups. No differences were observed between age groups in this PTM model, however, these animals may not reflect biological factors contributing to HIV risk such as those found in their human counterparts. This model is therefore not appropriate to explore human adolescent differences in HIV risk. Young women remain a key population at risk for HIV infection, and there is still a need for comprehensive assessment and intervention strategies for epidemic control of this uniquely vulnerable population.

Clinical and Molecular Properties of Human Immunodeficiency Virus-Related Diffuse Large B-Cell Lymphoma

Non-Hodgkin lymphoma is the most common malignancy affecting people living with HIV (PLWH). Among its several subtypes, diffuse large B-cell lymphoma (DLBCL) is an important manifestation within the HIV-infected compartment of the population. Since HIV is able to modulate B cells and promote lymphomagenesis through direct and indirect mechanisms, HIV-related DLBCL has specific characteristics. In this review, we address the clinical and molecular properties of DLBCL disease in the context of HIV infection, as well as the mechanisms by which HIV is able to modulate B lymphocytes and induce their transformation into lymphoma.

B cells are the predominant mediators of early systemic viral dissemination during rectal LCMV infection

Determining the magnitude of local immune response during mucosal exposure to viral pathogens is critical to understanding the mechanism of viral pathogenesis. We previously showed that vaginal inoculation of lymphocytic choriomeningitis virus (LCMV) fails to induce a robust innate immune response in the lower female reproductive tract (FRT), allowing high titer viral replication and a delay in T-cell-mediated viral control. Despite this immunological delay, LCMV replication remained confined mainly to the FRT and the draining iliac lymph node. Here, we show that rectal infection with LCMV triggers type I/III interferon responses, followed by innate immune activation and lymphocyte recruitment to the colon. In contrast to vaginal exposure, innate immunity controls LCMV replication in the colon, but virus rapidly disseminates systemically. Virus-induced inflammation promotes the recruitment of LCMV target cells to the colon followed by splenic viral dissemination by infected B cells, and to a lesser extent by CD8 T cells. These findings demonstrate major immunological differences between vaginal and rectal exposure to the same viral pathogen, highlighting unique risks associated with each of these common routes of sexual viral transmission.

Human Immunodeficiency Virus Immune Cell Receptors, Coreceptors, and Cofactors: Implications for Prevention and Treatment

In the last three decades, extensive research on human immunodeficiency virus (HIV) has highlighted its capability to exploit a variety of strategies to enter and infect immune cells. Although CD4(+) T cells are well known as the major HIV target, with infection occurring through the canonical combination of the cluster of differentiation 4 (CD4) receptor and either the C-C chemokine receptor type 5 (CCR5) or C-X-C chemokine receptor type 4 (CXCR4) coreceptors, HIV has also been found to enter other important immune cell types such as macrophages, dendritic cells, Langerhans cells, B cells, and granulocytes. Interestingly, the expression of distinct cellular cofactors partially regulates the rate in which HIV infects each distinct cell type. Furthermore, HIV can benefit from the acquisition of new proteins incorporated into its envelope during budding events. While several publications have investigated details of how HIV manipulates particular cell types or subtypes, an up-to-date comprehensive review on HIV tropism for different immune cells is lacking. Therefore, this review is meant to focus on the different receptors, coreceptors, and cofactors that HIV exploits to enter particular immune cells. Additionally, prophylactic approaches that have targeted particular molecules associated with HIV entry and infection of different immune cells will be discussed. Unveiling the underlying cellular receptors and cofactors that lead to HIV preference for specific immune cell populations is crucial in identifying novel preventative/therapeutic targets for comprehensive strategies to eliminate viral infection.

HIV-1 induces B-cell activation and class switch recombination via spleen tyrosine kinase and c-Jun N-terminal kinase pathways

OBJECTIVE

Patients infected by the HIV type 1 (HIV-1) frequently show a general deregulation of immune system. A direct influence of HIV-1 particles on B-cell activation, proliferation and B-cell phenotype alterations has been recently described. Moreover, expression of activation-induced cytidinedeaminase (AID) mRNA, which is responsible for class switch recombination (CSR) and somatic hypermutation (SHM), was reported to be overexpressed in B cells exposed to HIV-1.

DESIGN

Study of primary human B cells in an in-vitro model.

METHODS

In the current study, we evaluated which signalling pathways are activated in primary B cells after a direct contact with HIV-1 particles in vitro using different kinase inhibitors.

RESULTS

Here, we report that B-cell activation together with the increase of AID mRNA expression and the subsequent class switch recombination (CSR) in HIV-exposed B cells occurred through spleen tyrosine kinase (SYK) and c-Jun N-terminal kinase (JNK) pathways.

CONCLUSION

Therefore, we showed that HIV-1 could directly induce primary B-cell deregulation via SYK/B-cell receptor (BCR) engagement, and that activation was followed by the JNK pathway activation. To our knowledge, these data provide the first evidence that SYK/BCR activation was the first step for B-cell activation and CSR mechanism after HIV-1 stimulation in a T-cell-free context.

Epstein-Barr virus-driven lymphomagenesis in the context of human immunodeficiency virus type 1 infection

Epstein-Barr virus (EBV) is a ubiquitous human γ-herpes virus which establishes a life-long asymptomatic infection in immunocompetent hosts. In human immunodeficiency virus type 1 (HIV-1) infected patients, the impaired immunosurveillance against EBV may favor the development of EBV-related diseases, ranging from lymphoproliferative disorders to B cell non-Hodgkin's lymphomas (NHL). Antiretroviral therapy (ART) has significantly modified the natural course of HIV-1 infection, resulting in decreased HIV-1 plasmaviremia, increased CD4 lymphocytes, and decreased opportunistic infections, indicating a restoration of immune functions. However, the impact of ART appears to be less favorable on EBV-related malignancies than on other AIDS-defining tumors, such as Kaposi's sarcoma, and NHL remains the most common cancer during the ART era. EBV-driven tumors are associated with selective expression of latent oncogenic proteins, but uncontrolled lytic cycle with virus replication and/or reactivation may favor cell transformation, at least in the early phases. Several host's factors may promote EBV reactivation and replication; besides immunodepression, inflammation/chronic immune stimulation may play an important role. Microbial pathogen-associated molecular patterns and endogenous damage-associated molecular patterns, through Toll-like receptors, activate the immune system and may promote EBV reactivation and/or polyclonal expansion of EBV-infected cells. A body of evidence suggests that chronic immune stimulation is a hallmark of HIV-1 pathogenesis and may persist even in ART-treated patients. This review focuses on lymphomagenesis driven by EBV both in the context of the natural history of HIV-1 infection and in ART-treated patients. Understanding the mechanisms involved in the expansion of EBV-infected cells is a premise for the identification of prognostic markers of EBV-associated malignancies.

HIV-1 Trans Infection of CD4(+) T Cells by Professional Antigen Presenting Cells

Since the 1990s we have known of the fascinating ability of a complex set of professional antigen presenting cells (APCs; dendritic cells, monocytes/macrophages, and B lymphocytes) to mediate HIV-1 trans infection of CD4(+) T cells. This results in a burst of virus replication in the T cells that is much greater than that resulting from direct, cis infection of either APC or T cells, or trans infection between T cells. Such APC-to-T cell trans infection first involves a complex set of virus subtype, attachment, entry, and replication patterns that have many similarities among APC, as well as distinct differences related to virus receptors, intracellular trafficking, and productive and nonproductive replication pathways. The end result is that HIV-1 can sequester within the APC for several days and be transmitted via membrane extensions intracellularly and extracellularly to T cells across the virologic synapse. Virus replication requires activated T cells that can develop concurrently with the events of virus transmission. Further research is essential to fill the many gaps in our understanding of these trans infection processes and their role in natural HIV-1 infection.

Direct phenotypical and functional dysregulation of primary human B cells by human immunodeficiency virus (HIV) type 1 in vitro

Background

Human immunodeficiency virus type 1 (HIV-1) induces a general dysregulation of immune system. Dysregulation of B cell compartment is generally thought to be induced by HIV-related immune activation and lymphopenia. However, a direct influence of HIV-1 particles on B cells was recently proposed as the third pathway of B cells dysregulation.

Methods/Principal Findings

We evaluated the direct and specific consequences of HIV-1 contact on activation, survival, proliferation and phenotype of primary B cells in vitro. Moreover, we examined expression of activation-induced cytidine deaminase (AID) mRNA that is responsible for class switch recombination (CSR) and somatic hypermutation (SHM). Here, we report that changes observed in cellular proliferation, phenotypes and activation of B cells could be caused by direct contact between HIV-1 particles and primary B cells in vitro. Finally, direct HIV-1-derived B cells activation led to the increase of AID mRNA expression and its subsequent CSR function was detected in vitro.

Conclusion/Significance

We showed that HIV-1 could directly induce primary B cells dysregulation triggering phenotypical and functional abilities of B cells in vitro that could explain in some extent early B-cell abnormalities in HIV disease.

HIV reservoirs in vivo and new strategies for possible eradication of HIV from the reservoir sites

Even though the treatment of human immunodeficiency virus (HIV)-infected individuals with highly active antiretroviral therapy (HAART) provides a complete control of plasma viremia to below detectable levels (<40 copies/mL plasma), there is an unequal distribution of all antiretroviral drugs across diverse cellular and anatomic compartments in vivo. The main consequence of this is the acquisition of resistance by HIV to all known classes of currently prescribed antiretroviral drugs and the establishment of HIV reservoirs in vivo. HIV has a distinct advantage of surviving in the host via both pre-and postintegration latency. The postintegration latency is caused by inert and metabolically inactive provirus, which cannot be accessed either by the immune system or the therapeutics. This integrated provirus provides HIV with a safe haven in the host where it is incessantly challenged by its immune selection pressure and also by HAART. Thus, the provirus is one of the strategies for viral concealment in the host and the provirus can be rekindled, through unknown stimuli, to create progeny for productive infection of the host. Thus, the reservoir establishment remains the biggest impediment to HIV eradication from the host. This review provides an overview of HIV reservoir sites and discusses both the virtues and problems associated with therapies/strategies targeting these reservoir sites in vivo.

Memory B cell function in HIV-infected children-decreased memory B cells despite ART

B cell dysfunction is a well-studied complication of HIV infection in adults. Data on B cell differentiation in normal and HIV-infected children are lacking. We show the distribution of B cell subsets and immunoglobulin levels in HIV-infected children compared with controls. Furthermore, we observe the long-term B cell reconstitution of vaccine-specific immunity after antiretroviral therapy (ART). Phenotype of B cells (naive, non-switched memory, switched memory) was analyzed in 48 infected children and 62 controls. In nine HIV-infected children, functional reconstitution was quantified by tetanus-specific antibodies and by performing a lymphocyte transformation test (LTT) in a longitudinal approach. Switched memory B cells are significantly reduced in HIV-infected children. Vaccine-specific antibodies and response to LTT increase after initiation of ART. Our data indicate a significant dysfunction in the B cell system, despite effective ART. Partial reconstitution of humoral immunity may have therapeutic implications in a subset of HIV-infected children.

Postinfection passive transfer of KD-247 protects against simian/human immunodeficiency virus-induced CD4+ T-cell loss in macaque lymphoid tissue

BACKGROUND

Preadministration of high-affinity humanized anti-HIV-1 mAb KD-247 by passive transfer provides sterile protection of monkeys from heterologous chimeric simian/human immunodeficiency virus infection.

METHODS

Beginning 1 h, 1 day, or 1 week after simian/human immunodeficiency virus-C2/1 challenge (20 50% tissue culture infective dose), mature, male cynomolgus monkeys received multiple passive transfers of KD-247 (45 mg/kg) on a weekly basis for approximately 2 months. Concentrations and viral loads were measured in peripheral blood, and CD4 T-cell counts were examined in both peripheral blood and various lymphoid tissues.

RESULTS

Pharmacokinetic examination revealed similar plasma maintenance levels ranging from 200 to 500 microg/ml of KD-247 in the three groups. One of the six monkeys given KD-247 could not maintain these concentrations, and elicitation of anti-KD-247 idiotype antibody was suggested. All monkeys given KD-247 exhibited striking postinfection protection against both CD4 T-cell loss in various lymphoid tissues and atrophic changes in organs compared with control group animals treated with normal human immunoglobulin G. The KD-247-treated groups were also partially protected against plasma viral load elevation in peripheral blood samples, although the complete protection previously reported with preadministration of this mAb was not achieved.

CONCLUSION

Postinfection passive transfer of humanized mAb KD-247 with strong neutralizing capacity against challenged virus simian/human immunodeficiency virus-C2/1 protected CD4 T cells in lymphoid organs.

B cells in HIV infection and disease

In recent years, intense research efforts have been dedicated to elucidating the pathogenic mechanisms of HIV-associated disease progression. In addition to the progressive depletion and dysfunction of CD4(+) T cells, HIV infection also leads to extensive defects in the humoral arm of the immune system. The lack of immune control of the virus in almost all infected individuals is a great impediment to the treatment of HIV-associated disease and to the development of a successful HIV vaccine. This Review focuses on advances in our understanding of the mechanisms of B-cell dysfunction in HIV-associated disease and discusses similarities with other diseases that are associated with B-cell dysfunction.

Humoral immunity to HIV-1: neutralisation and antibody effector functions

Several features of HIV have frustrated efforts to develop a vaccine able to induce broadly neutralising antibodies. The enormous genetic diversity of HIV is a major factor, accompanied by the camouflaged nature of the envelope spike, upon which HIV depends for cellular entry and to which antibodies must bind to neutralise. The picture is further complicated by the presence of nonfunctional envelope glycoproteins on the surface of HIV that are immunogenic. Consequently, HIV attracts antibodies that do not directly neutralise the virus but still activate complement and engage Fc receptors, which can both enhance and inhibit infection. The various effects that anti-envelope antibodies have on HIV infection will be reviewed here. Further research is needed to determine if these in vitro-characterised activities have relevance in vivo, and if some of the undesirable effects of non-neutralising antibodies can be avoided or the beneficial effects harnessed.

Pathogenic mechanisms of B-lymphocyte dysfunction in HIV disease

HIV disease is associated with abnormalities in all major lymphocyte populations, including B cells. Aberrancies in the B-cell compartment can be divided into 3 broad categories: changes that arise as a result of HIV-induced immune activation, changes that arise as a result of HIV-induced lymphopenia, and changes that arise independently of these 2 parameters. We review recent developments in all 3 categories of abnormalities and highlight how observations made in the early years of the HIV epidemic are better understood today in large part because of the advent of effective antiretroviral therapy. Insight into the mechanisms of B-cell dysfunction in HIV disease has also been achieved as a result of increased knowledge of the B-cell subpopulations as they exist in healthy individuals, compared with their abnormalities in HIV-infected individuals. A better understanding of the pathogenic mechanisms of B-cell abnormalities in HIV disease can potentially lead to new strategies for improving antibody responses against opportunistic pathogens that afflict HIV-infected individuals and against HIV itself, in the context of both HIV infection and an antibody-based HIV vaccine.

Dynamic analysis of genetic diversity of gag and env regions of HIV-1 CRF07_BC recombinant in intravenous drug users in Xinjiang Uvghur Autonomous Region, China

The aim of this study was to investigate the genetic variation of HIV-1 CRF07_BC, the most prevalent circulating strain in intravenous drug users (IDUs) in China. We studied the diversity in the C2-V5 region of the HIV-1 env gene and in the p17-p24 region of the HIV-1 gag gene from the same samples in 12 IDUs who were divided into two groups according to the length of infection time. Two IDUs were longitudinally monitored from the time of seroconversion for 2-2.5 years. The viral divergence from the founder strain and the viral population diversity between sequential time points were analyzed in two men. The data show that the divergence of the env gene is higher than that of gag in general, while the diversity of the gag gene is sometimes higher than that of env during the course of HIV evolution. In addition, env and gag gene diversity increased over time. The observed patterns and associations may enhance our understanding of HIV-1 evolution.

Role for CD21 in the establishment of an extracellular HIV reservoir in lymphoid tissues

Follicular dendritic cells (FDC) represent a major extracellular reservoir for HIV. A better understanding of the mechanisms of virion attachment to FDC may offer new avenues for reducing viral burdens in infected individuals. We used a murine model to investigate the establishment of extracellular HIV reservoirs in lymph nodes (LN). Consistent with findings in human tissues, CD21 was required for trapping of HIV to LN cells, as evidenced by significantly reduced virion binding when mice were pretreated with a C3 ligand-blocking anti-CD21 mAb and absence of virion trapping in CD21 knockout mice. Also consistent with findings in human tissues, the majority of HIV virions were associated with the FDC-enriched fraction of LN cell preparations. Somewhat surprisingly, HIV-specific Abs were not essential for HIV binding to LN cells, indicating that seeding of the FDC reservoir may begin shortly after infection and before the development of HIV-specific Abs. Finally, the virion-displacing potential for anti-CD21 mAbs was investigated. Treatment of mice with anti-CD21 mAbs several days after injection of HIV significantly reduced HIV bound to LN cells. Our findings demonstrate a critical role for CD21 in HIV trapping by LN cells and suggest a new therapeutic avenue for reducing HIV reservoirs.

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.

HIV and complement: hijacking an immune defense

The complement system is a central player of the innate immune system. Activation of the complement system protects the host against pathogens. However, uncontrolled synthesis can be detrimental to host. This concise review summarizes the current understanding of the mechanism(s) of complement activation, the mechanism of C3 regulation, and the role of complement in human immunodeficiency virus (HIV) pathogenesis with emphasis on the cross-talk between HIV and complement system in NeuroAIDS and HIV-associated nephropathy (HIVAN).

DC-SIGN on B lymphocytes is required for transmission of HIV-1 to T lymphocytes

Infection of T cells by HIV-1 can occur through binding of virus to dendritic cell (DC)-specific ICAM-3 grabbing nonintegrin (DC-SIGN) on dendritic cells and transfer of virus to CD4⁺ T cells. Here we show that a subset of B cells in the blood and tonsils of normal donors expressed DC-SIGN, and that this increased after stimulation in vitro with interleukin 4 and CD40 ligand, with enhanced expression of activation and co-stimulatory molecules CD23, CD58, CD80, and CD86, and CD22. The activated B cells captured and internalized X4 and R5 tropic strains of HIV-1, and mediated trans infection of T cells. Pretreatment of the B cells with anti–DC-SIGN monoclonal antibody blocked trans infection of T cells by both strains of HIV-1. These results indicate that DC-SIGN serves as a portal on B cells for HIV-1 infection of T cells in trans. Transmission of HIV-1 from B cells to T cells through this DC-SIGN pathway could be important in the pathogenesis of HIV-1 infection.

A cell surface molecule, DC-SIGN, is known to bind the AIDS virus, human immunodeficiency virus 1 (HIV-1), on dendritic cells. HIV-1 can then be transferred from these dendritic cells to CD4⁺ T cells, in which the virus replicates and kills the T cells. Here, Rappocciolo and colleagues present their findings that DC-SIGN serves a similar function on a subset of B cells of the peripheral blood and tonsils. Although B cells that express DC-SIGN do not replicate HIV-1, they serve as portals for transfer and enhanced HIV-1 infection of CD4⁺ T cells, the major site of virus replication in the host. This newly described pathway for HIV-1 infection of T cells via B cells could be important in the pathogenesis of the virus infection.

Evolutionary dynamics of HIV-1 and the control of AIDS

Human immunodeficiency viruses (HIV) have exhibited an extraordinary capacity for genetic change, exploring new evolutionary space after each transmission to a new host. This presents a great challenge to the prevention and management of HIV-1 infection. At the same time, the relentless diversification of HIV-1, developing as it does under the constraints imposed by the human immune system and other selective forces, contains within it information useful for understanding HIV epidemiology and pathogenesis. Comparing the sheer mutational potential of HIV with actual data representing viral lineages that can survive selection suggests that HIV does not have unlimited capacity for change. Rather, clinical and bioinformatic data suggest that, even in the most diverse gene of the most highly variable organism, natural selection places severe limits on the portion of amino acid sequence space that ensures viability. This suggests some optimism for those attempting to identify sets of antigens that can generate effective humoral and cellular immune responses against HIV.

Elevated B-cell autoantibodies among HIV+ transplant candidates: crossmatch implications

We report our experience in assessing autoantibodies among HIV+ patients considered for renal transplantation. Autoantibodies against autologous T and B cells were determined by complement-dependent cytotoxicity autocrossmatching (CDC) or flow cytometric autocrossmatching (FCXM) for 28 HIV+ and 72 HIV- men. T-cell CDC was negative among HIV+ and HIV- individuals (0%). In contrast, B-cell CDC was higher among HIV+ than HIV- patients (71% vs 4%, P = .001). However, HIV+ patients also showed unusual sensitivity to complement that potentially invalidated the B-cell CDC. Complement sensitivity was higher among those with positive versus negative HIV RNA (71% vs 25%, P < .01). Alternate use of FCXM showed equivalent T-cell FCXM between HIV+ versus HIV- individuals (5% vs 1%, P = NS). However, B-cell FCXM was more prevalent among HIV+ than HIV- patients (45% vs 2%, P < .01). B-cell FCXM was higher among patients with positive than negative HIV RNA (57% vs 25%, P < .05). Simulated allocrossmatching against unrelated DR-matched donors showed that two out of four HIV+ patients with positive FCXM had positive allocrossmatches that were eliminated when allocrossmatching was repeated using autoabsorbed serum. We conclude that HIV+ patients are more likely to produce B-cell autoantibodies than HIV- individuals, which, if not realized, could cause false-positive allocrossmatches and inappropriate transplant denial.

Diversity, divergence, and evolution of cell-free human immunodeficiency virus type 1 in vaginal secretions and blood of chronically infected women: associations with immune status

Most human immunodeficiency virus type 1 (HIV-1) infections are believed to be the result of exposure to the virus in genital secretions. However, prevention and therapeutic strategies are usually based on characterizations of HIV-1 in blood. To understand better the dynamics between HIV-1 quasispecies in the genital tract and blood, we performed heteroduplex assays on amplified env products from cell-free viral RNA in paired vaginal secretion (VS) and blood plasma (BP) samples of 14 women followed for 1.5 to 3.5 years. Diversity and divergence were less in VS than in BP (P = 0.03 and P < 0.01, respectively), and divergence at both sites was correlated with blood CD4(+) cell levels (VS, P = 0.05; BP, P = 0.01). Evolution of quasispecies was observed in 58% of the women; the loss or gain of quasispecies in VS or BP was always accompanied by such changes at the other site. In addition, sustained compartmentalization of quasispecies in VS was found for four women, even as CD4(+) cell levels decreased to low levels (<50 cells/microl). Quasispecies changes over time were associated with fluctuations in CD4(+) cell levels; concordant increases or decreases in VS and BP divergence had greater CD4(+) cell level changes than intervals with discordant changes (P = 0.05), and women with evolving quasispecies had greater decreases in CD4(+) cell levels compared to that for women who maintained the same quasispecies (P < 0.05). Thus, diversity, divergence, and evolution of cell-free HIV-1 in VS can be different from that in BP, and dynamics between their respective quasispecies are associated with changes in CD4(+) cell levels.

Human immunodeficiency virus type 1 Tat protein modulates cell cycle and apoptosis in Epstein-Barr virus-immortalized B cells

Patients infected with human immunodeficiency virus type 1 (HIV-1) develop a spectrum of B cell lymphoproliferative disorders ranging from polyclonal B cell activation to B cell lymphomas. While a direct role of Epstein-Barr virus (EBV) is well recognized for most of these lesions, recent findings have suggested that transactivator HIV-1 Tat protein might be involved in the pathogenesis of B cell lymphomas. Tat-expressing EBV-positive B cells were generated by transduction with a retroviral Tat-encoding vector. B(Tat+) cells expressed lower levels of anti-apoptotic protein Bcl-2 than parental and control B(Tat-) cells, generated by transduction with an empty retroviral vector, and were more prone to apoptosis upon serum withdrawal, as assessed by analysis of annexin V-stained cells and cleavage of poly-ADP-ribose-polymerase by caspase 3. Nevertheless, in serum starvation, B(Tat-) cells mainly exhibited the Rb hypo-phosphorylated form, underwent cell cycle arrest, and grew in single cell suspension, while B(Tat+) cells displayed the Rb hyper-phoshorylated form, progressed throughout the cell cycle, and retained the ability to grow in small clumps. Finding that B(Tat+) cells maintained proliferative capacity upon serum withdrawal suggests that cells expressing Tat have growth advantages among the EBV-driven cell proliferations and may originate B cell clones with more oncogenic potential.

HIV-1 dynamics in vivo: implications for therapy

The advent of potent combination antiretroviral therapy has been an important breakthrough in the treatment of HIV-1 infection, resulting in marked reductions in HIV-1-related morbidity and mortality. Antiretroviral therapy has also provided researchers with a powerful tool to perturb the equilibrium of viral production and viral clearance, allowing them to dissect the underlying dynamics that control the pathogenesis of AIDS. Here, we review our current understanding of the sources of HIV-1 production, the estimates for the virion and the host-cell half-lives, and the pathways of virion trafficking and clearance. We also discuss the obstacles that result from the ability of HIV-1 to remain dormant for a prolonged period of time in a subset of long-lived cells, despite an apparently effective antiretroviral treatment.

Does AID aid AIDS?

During AIDS, the acquisition of mutations in the HIV-1 gp120 envelope glycoprotein leads to the switch from primary R5 (CCR5-using) to highly cytopathic X4 (CXCR4-using) HIV-1 variants. Based on the already known sequence homology between IgV genes and the gp120-coding region of the env gene, as well as on somatic hypermutation of multiple proto-oncogenes, the somatic hypermutation hypothesis for the mechanism of R5-X4 HIV-1 switching is proposed as follows. This switch takes place in the germinal center (GC) B cells due to the aberrant somatic hypermutation of the gp120-coding part of the HIV-1 env gene. Activation-induced cytidine deaminase (AID) is required for this process. Activation through IL4R and CD40 is required both for infection of GC B cells with HIV-1 and for induction of AID expression in the same cells. B cell infection with R5 HIV-1 variants is the limiting stage in the process of the viral phenotypic switch during the asymptomatic period of AIDS. Overall up-regulation of CXCR4 coreceptor on the GC B cells and the CD4(+) T cells surrounding the GC provides the predominant replication and acquisition of the newly formed X4 HIV-1 variants.

Occurrence and Management of Opportunistic Infections Associated with HIV/AIDS in Asia

Illnesses, diseases and malignancies occur among HIV-infected individuals along a continuum. These are directly correlated with the degree of immune suppression and are caused by common patho gens and opportunistic infections. In decreasing order offrequency, frequent opportunistic infections and malignancies that occur in Asia are: Mycobacterium tuberculosis, Cryptococcus neoformans, Candida spp., Herpes simplex, Cryptosporidium parvum, Pneumocystis carinii, Toxoplasma gondii, non-Hodgkin's lymphoma and Kaposi's sarcoma. The association of morbidityand mortality due to co-infection with HIV and M.tuberculosis has become more evident in the region. Natural history studies conducted in Mumbai and Bangkok have reported incubation periods from infection to AIDS of eight and nine years respectively. Despite the advent of antiretroviral therapy (ART) and improved affordability of the generic drugs, only 30,000 (2 to 3 per cent) of the estimated 1.3 million eligible persons with AIDS in South Asia are presently on AR T. Apparently, the focus of the low-cost care in the region still continues to be of care and management of prevalent opportunistic infections. As care practices start to include ART over the next few years, there will be consequent change in the occurrence of opportunistic infections and need for their prophylaxis.

Importance and detection of virus reservoirs and compartments of HIV infection

Current therapies for treating HIV-1 infection are capable of suppressing virus load in blood to undetectable levels, and result in marked clinical improvement. Despite this suppression, HIV-1 infection persists and virus load quickly rebounds when therapy is interrupted. The origin of the rebounding virus is unknown, but is thought to result from continuing viral replication in anatomic or cellular compartments, and the release of virus from latent infection in reservoirs.