Rapid Decline In CD4 Research Articles

Introduction of Mutant APOBEC3G Into CD4+ T-Cells to Resist HIV-1

Introduction: Human immunodeficiency virus 1 (HIV-1) is a potentially lethal retrovirus with high genetic diversity and replication ability. HIV-1 mainly targets human CD4+ T-cells, causing a rapid decline in CD4+ T-cell count after infection. Apolipoprotein B mRNA Editing Enzyme Catalytic Subunit 3G (APOBEC3G or A3G) is a human anti-viral enzyme that blocks early stages of HIV-1 replication by deaminating the cytosine residues to uracil in the viral minus-strand DNA during reverse transcription. Nevertheless, HIV-1 overcomes A3G anti-viral activity by employing Vif accessory protein to degrade A3G. Due to a proline/aspartate point mutation in residue 129 (P129D), an artificial A3G mutant, also known as A3G-P129D, was found to be resistant against diverse Vif variants, including HIV-1 Vif, thereby shedding light on a potential A3G-mediated gene therapy for HIV-1. Methods: We propose that, using CRISPR-Cas9 tools, the P129D mutation will be introduced into A3G expressed by human hematopoietic stem cells. Engineered stem cells will be transplanted into Non-Obese Diabetic Severe Combined Immunodeficient Gamma (NSG) mice, which will later be infected with HIV-1. Following infection, flow cytometry will be used to compare the CD4+ T-cell count in mice that express A3G-P129D versus control mice transplanted with unmodified human CD4+ T-cells. Results: We expect a notably higher CD4+ T-cell count in mice carrying the P129D mutation than in the control group, which would be attributed to the efficient inhibition of HIV-1 replication by the mutant A3G. Discussion: Transforming human A3G to A3G-P129D will prevent Vif-mediated degradation of A3G, allowing A3G to efficiently target HIV-1. Thus, this treatment would ultimately block HIV-1 replication and prevent CD4+ T-cell depletion. Conclusion: Overall, our novel gene therapy approach could open the door to a potential one-time treatment for HIV-1 infected patients.

Differential Pathogenicity of SHIV KB9 and 89.6 Env Correlates with Bystander Apoptosis Induction in CD4+ T cells.

SHIV variants KB9 and 89.6 show differential pathogenesis in primate models with KB9 causing rapid CD4 decline while 89.6 failing to induce disease. We attempted to determine whether the differential pathogenicity of KB9 versus 89.6 was a result of differential bystander apoptosis inducing potential (AIP) of the Env glycoproteins from these viruses. We find that the KB9 Env was highly potent at inducing bystander apoptosis in CD4+ target cells compared to 89.6 Env. Cell death induction by KB9 showed classical signs of apoptosis including mitochondrial depolarization, caspase activation and PARP cleavage. Inhibiting Env mediated fusion by T20 peptide inhibited KB9 mediated bystander apoptosis. KB9 and 89.6 differed in terms of co-receptor usage with 89.6 preferring CXCR4 while KB9 using both CXCR4 and CCR5 with equal efficiency. Our study suggests that higher bystander AIP of KB9 Env compared to 89.6 may be the basis for the differential pathogenesis of these viruses.

Decreased CD4+CD8low T cells in early HIV infection are associated with rapid disease progression

BackgroundHIV rapid progressors (RPs) present with a rapid decline of CD4+ T cells within a few years of infection. Determining the underlying mechanisms throughout this decline is important to identify prognostic biomarkers and intervention strategies. Determining the numbers of CD4+ and CD8+ T cells is essential for monitoring the immune status of HIV infected patients. There are additional kinds of cell subtypes in T cells, but their relationship to the rapid progression of HIV disease is not well defined. MethodsNineteen RPs and twenty-one chronic progressors (CPs) were enrolled in this study. Based on the intensity of CD4 and CD8 expression, different T cell subtypes were identified, including CD4+CD8+T cells, CD4−CD8− T cells, CD4+CD8low T cells and CD4−CD8low T cells. Alterations in these T cell subtypes in early HIV infection (within 120 days of infection) between RPs and CPs were measured, and the relationships between these subtypes and HIV disease progression were investigated. In addition, expression of IFN-γ in T cell subtypes after PMA stimulation was analyzed by flow cytometry. ResultsWe found that during early HIV infection, CD4+CD8low T cells both significantly decreased in numbers and percentages in RPs compared to CPs. Furthermore, baseline CD4+CD8low T cells positively correlated not only with baseline CD4+T cells but also with CD4+T cells 12 months after infection. Moreover, survival analysis indicated that low levels of baseline CD4+CD8low T cells significantly accelerated the decline in CD4+ T cells as well as increased viral loads. CD4+CD8low T cells secreted significantly more IFN-γ after PMA stimulation compared to CD4+CD8−T cells and CD4−CD8+T cells, which may be beneficial for the prevention of disease progression. ConclusionsOur results identified that in early stage HIV-1 infection, a subtype of T cells, CD4+CD8low, are associated with subsequent disease progression.

Reduced eIF3d accelerates HIV disease progression by attenuating CD8+ T cell function

BackgroundIn human immunodeficiency virus (HIV) infection, 10–15% of individuals exhibit a rapid decline in CD4+ T cells and become rapid progressors (RPs). Overall, understanding the factors affecting rapid disease progression in early HIV infection (EHI) can aid in treatment initiation. Recent studies show that eIF3s, classic scaffold proteins during the translation initiation process, can directly promote or inhibit the translation of mRNA, therefore participating in the regulation of cell function. However, to our knowledge, it has not been addressed whether eIF3s are involved in the diverse prognosis of HIV infection.MethodsExpression of eIF3s in primary cells from early or chronic HIV-infected patients was detected by real-time PCR. To investigate the potential mechanisms of eIF3d in the regulation of CD8+ T cell function, complete transcriptomes of eIF3d-inhibited Jurkat T cells were sequenced by RNA sequencing (RNA-Seq). Additionally, to examine the effect of eIF3d on CD8+ T cell function, eIF3d expression was inhibited alone or in combination with SOCS-7 knockdown by siRNA in isolated CD8+ T cells. CD8+ T cell proliferation, IFN-r secretion and apoptosis were detected by flow cytometry. Moreover, the effect of eIF3d on HIV replication was evaluated in Jurkat cells, peripheral blood mononuclear cells (PBMCs) and CD4+ T cells with eIF3d knockdown using a pNL4-3 pseudotyped virus.ResultsAt approximately 100 days of infection, only eIF3d was markedly decreased in RPs compared with chronic progressors (CPs). Expression of eIF3d correlated significantly with disease progression in EHI. Based on in vitro analyses, reduced eIF3d expression led to decreased proliferation and IFN-γ secretion and increased apoptosis in CD8+ T cells. Inhibited expression of eIF3d caused enhanced expression of SOCS-7, and inhibiting SOCS-7 expression by siRNA rescued the attenuated CD8+ T cell function caused by eIF3d. Finally, when eIF3d was inhibited in Jurkat cells, PBMCs and CD4+ T cells, pNL4-3-VSV-G virus replication was enhanced.ConclusionsThe current data highlight the importance of eIF3d in HIV infection by inhibiting CD8+ T cell function and promoting viral replication. Our study provides potential targets for improved immune intervention.

Rapid CD4 decline prior to antiretroviral therapy predicts subsequent failure to reconstitute despite HIV viral suppression.

HIV-1 infection is characterized by loss of CD4T cells, leading to immunodeficiency. Initiation of antiretroviral therapy (ART) results in suppression of the viral load and increased CD4 counts. Both viral and host factors determine CD4 cell responses to ART with approximately 15-30% of individuals having suboptimal increase of CD4T cell count, most commonly due to lack of compliance to ART. A smaller fraction of patients will have immune reconstitution failure and suboptimal CD4 increase despite suppression of HIV replication, and these individuals are at risk for adverse health outcomes. We sought to characterize the factors associated with decreased immunological response among Manitoba's HIV patient population. This retrospective case-control study included HIV patients with immune reconstitution failure despite suppression of HIV replication by ART. The immune reconstitution failure was defined by CD4 cell count increase from baseline of less than 100 CD4 cells/mm3 or lack of increase to above 200 CD4 cells/mm3 within one year of viral load suppression. Age and nadir CD4 cell counts are known risk factors associated with immune reconstitution failure. We chose controls (Patients with immune reconstitution success) of similar age and CD4 nadir cell with cases (Patients with immune reconstitution failure). We explored the potential effects of gender, HLA type, presence of co-infection, ethnicity, ART type, and rate of pre-treatment CD4 decline among cases and controls. Of more than 550 patients followed by our HIV clinic, 42 individuals met our definition of immune reconstitution failure and they were assigned to the cases group. 31 patients, comprising a range of ages and CD4 nadirs similar to those of the cases, were assigned to the control group. Our primary analysis was a regression model, predicting post-ART change in CD4 over time. After controlling for age and nadir CD4 cell counts, the only potential predictor that appears consistently associated with the rate of post-ART rise in CD4 over time in our cohort, regardless of the other variables that we have controlled for, is the rate of decline in CD4 pre-ART initiation. Several factors have been variably correlated with immune reconstitution failure of CD4 T cell count. Age and low CD4 nadir are factors previously shown to correlate with immune reconstitution failure; and we have controlled for them in our study. Another possible predictor is the rate of decline in CD4 pre-ART, which can serve as an additional marker of reconstitution failure and necessitate prioritizing individuals to ART initiation or identification of a subset of individuals that may be targeted for future adjunct strategies to improve immune recovery.

Transmission of survival signals through Delta-like 1 on activated CD4+ T cells.

Notch expressed on CD4+ T cells transduces signals that mediate their effector functions and survival. Although Notch signaling is known to be cis-inhibited by Notch ligands expressed on the same cells, the role of Notch ligands on T cells remains unclear. In this report we demonstrate that the CD4+ T cell Notch ligand Dll1 transduces signals required for their survival. Co-transfer of CD4+ T cells from Dll1−/− and control mice into recipient mice followed by immunization revealed a rapid decline of CD4+ T cells from Dll1−/− mice compared with control cells. Dll1−/− mice exhibited lower clinical scores of experimental autoimmune encephalitis than control mice. The expression of Notch target genes in CD4+ T cells from Dll1−/− mice was not affected, suggesting that Dll1 deficiency in T cells does not affect cis Notch signaling. Overexpression of the intracellular domain of Dll1 in Dll1-deficient CD4+ T cells partially rescued impaired survival. Our data demonstrate that Dll1 is an independent regulator of Notch-signaling important for the survival of activated CD4+ T cells, and provide new insight into the physiological roles of Notch ligands as well as a regulatory mechanism important for maintaining adaptive immune responses.

Rate of CD4 Decline and Factors Associated with Rapid CD4 Decline in Asymptomatic HIV-Infected Patients.

The accurate marker to assess the risk of disease progression in HIV disease is CD4 count. CD4 decline to <200 cells/mm3 prompts the patients to have risk of opportunistic infections. A retrospective cohort study was conducted in asymptomatic HIV-infected patients who had CD4 count>200 cell/mm3, were antiretroviral naive, and had ≥1-year follow-up. Eighty patients, with mean age of 36.4 (standard deviation [SD]=9.1) years and 58.8% females, were analyzed. The mean (SD) baseline CD4 count was 423 (119) cells/mm3. During the median (IQR) time of 29.0 (14.1-49.6) months, 26.3% had CD4 declined to <200 cells/mm3. From Cox proportional hazard model, only baseline CD4 count<350 cells/mm3 was significantly associated with rapid decline in CD4 count (HR 4.208; 95%CI, 1.428-12.397; P=.009). Age, gender, comorbid disease, risk of HIV infection, duration of HIV diagnosis, and body weight were not associated with rapid CD4 decline. This indicates that asymptomatic patients with CD4 count<350 cells/mm3 are at priority for antiretroviral therapy in resource-limited settings.

Rapid human immunodeficiency virus disease progression is associated with human leukocyte antigen-B homozygocity and human leukocyte antigen-B51 in a cohort from Manitoba, Canada

Background: Human immunodeficiency virus type 1 (HIV-1) infection is associated with variable rates of disease progression, influenced by the quality of CD8 T-lymphocyte response, which is determined by human leukocyte antigen (HLA) I alleles. Some individuals progress slowly and maintain viral control, while at the opposite end of the spectrum some individuals endure a faster progression with rapid CD4 decline. We sought to determine the role of HLA-B allele frequency on rapid HIV disease progression. It was hypothesized that rapid progression is associated with the presence of high allele frequency of HLA-B35 and HLA-B homozygocity. Methods: This retrospective cohort study was conducted in the Manitoba HIV Program, Health Sciences Centre, a tertiary care facility in Winnipeg, Manitoba, Canada. We defined a set of new criteria to describe a subset of individuals with the most rapid HIV disease progression, and collected demographic, clinical, laboratory (CD4 count, viral load) and HLA data on a subset of 20 individuals meeting these criteria. Results: Among those individuals who display extreme rapid progression, an overrepresentation of Aboriginal ethnicities, high frequencies of HLA-B35 and significantly higher rates of HLA-B51, as well as a very high rate of homozygocity for HLA-B alleles, were observed. Conclusions: Individuals with the most rapid disease progression have higher rates of HLA-B homozygocity, HLA-B51 alleles and higher viral loads than those with normal progression rates. This group, at the extreme end of the spectrum of progression, should be targeted for early treatment.

AN INVESTIGATION OF SOCIAL AND CLINICAL FACTORS INFLUENCING TRENDS IN CD4 COUNT AMONG HIV-INFECTED PATIENTS IN SASKATOON, CANADA

IntroductionThe province of Saskatchewan has the highest incidence of HIV in Canada, and high AIDS-related morbidity and mortality. The HIV infected population in Saskatchewan is unique in Canada because the...

HIV-1 Clade D Is Associated with Increased Rates of CD4 Decline in a Kenyan Cohort

HIV-1 is grouped phylogenetically into clades, which may impact rates of HIV-1 disease progression. Clade D infection in particular has been shown to be more pathogenic. Here we confirm in a Nairobi-based prospective female sex worker cohort (1985–2004) that Clade D (n = 54) is associated with a more rapid CD4 decline than clade A1 (n = 150, 20.6% vs 13.4% decline per year, 1.53-fold increase, p = 0.015). This was independent of “protective” HLA and country of origin (p = 0.053), which in turn were also independent predictors of the rate of CD4 decline (p = 0.026 and 0.005, respectively). These data confirm that clade D is more pathogenic than clade A1. The precise reason for this difference is currently unclear, and requires further study. This is first study to demonstrate difference in HIV-1 disease progression between clades while controlling for protective HLA alleles.

Association of APOBEC3G genotypes and CD4 decline in Thai and Cambodian HIV-infected children with moderate immune deficiency

IntroductionHuman APOBEC3G is a host defense factor that potently inhibits HIV replication. We hypothesize that HIV-infected children with a genetic variant of APOBEC3G will have a more rapid disease progression.MethodsAntiretroviral therapy (ART)-naïve children, aged 1–12 years old with CD4 15-24% and without severe HIV-related symptoms were enrolled. The children had CD4% and absolute CD4 counts every 12 weeks and HIV-RNA every 24 weeks until 144 weeks. ART was started when CD4% declined to < 15% or AIDS-related events developed.APOBEC3G genetic variants were performed by PCR-based restriction fragment length polymorphism techniques from peripheral blood mononuclear cells. Random-effect linear regression analysis was performed to correlate APOBEC3G genotypes and disease progression.Results147 children, 35% male, with a median (IQR) age of 6.5 (4.3-8.8) years were enrolled. CDC N:A:B were 1:63:36%. Median baseline values were 20% for CD4% 605 cells/mm3 for CD4 count and 4.7 log10copies/mL for HIV-RNA.The frequencies of APOBEC3G genotypes AA (186H/H), AG (186H/R), GG (186R/R) were 86%, 12%, and 2% respectively. The APOBEC3G genotype GG was associated with a significant decline in CD4% -5.1% (−8.9 to −1.2%), p<0.001, and CD4 counts −226 (−415 to −34) cells/mm3, p<0.001 by random-effect liner regression analysis. No significant associations of APOBEC3G genotypes with HIV-RNA changes overtime (p=0.16) or progression to CDC B and C (p=0.49) were observed.ConclusionsAPOBEC3G genotype GG was significantly associated with a more rapid decline in CD4. APOBEC3G’s antiviral effects on HIV disease progression in children should be further explored.

Characterization of a SHIV162P3 variant evolved in an infected rhesus macaque with persistent plasma viremia

Typically plasma viremia is controlled in macaques challenged with R5 tropic SHIV162P3 during the chronic phase of infection. However, in a few infected animals it sustains for a prolonged period. Persistent plasma viremia in two such macaques led to a rapid decline of CD4+ T-cells in blood leading to the induction of AIDS. A viral variant from one of these animals showed sensitivity to soluble CD4 and maraviroc similar to the challenge virus. However, it exhibited reduced sensitivity to anti-gp120 antibody b12 and to sera from SHIV162P3-infected macaques or HIV-1-infected humans. Molecular sequencing of the env gene from this virus revealed multiple mutations clustering on the V1 domain of gp120. These results demonstrate that evolution of the envelope in SHIV-infected macaques may lead to the emergence of a viral variant with altered immunological characteristics.

CCR5 or CXCR4 use influences the relationship between CD4 cell depletion, NKp44L expression and NK cytotoxicity in SHIV-infected macaques

HIV-1 infection is characterized by a progressive decline of CD4 cell count, the underlying mechanisms of which are still debated. We recently found that during HIV-1 infection, CD4 T cells overexpress a ligand of the NK activating receptor NKp44 (NKp44L) and are sensitized to NK cytolytic activity. The expression of NKp44L is triggered by a highly conserved motif of gp41 (3S) and is inhibited by anti-3S antibodies. To assess whether viral tropism can affect NKp44L expression, NK cytotoxicity, and anti-3S antibodies production, 10 macaques were infected either with the CCR5 tropic SHIV162P3 or with a CXCR4/CCR5 dual-tropic SHIV89.6P. In SHIV162P3-infected macaques, expression of NKp44L was inversely correlated with anti-3S antibodies, in relation to CD4 depletion and NK cytotoxicity. By contrast, no such correlation was found in macaques infected with SHIV89.6P which, induced a rapid decline of CD4 T cells. These results highlight the key role played by NK cells in CD4 cell count decline with respect to coreceptor usage, and provided the setting to investigate new strategies for preventive and/or therapeutic immunization to stimulate anti-3S antibodies.

Rapid CD4 decline after interruption of non-nucleoside reverse transcriptase inhibitor-based antiretroviral therapy in a resource-limited setting

BackgroundNon-nucleoside reverse transcriptase inhibitor (NNRTI) with stavudine and lamivudine is widely used as the first-line antiretroviral therapy (ART) in resource-limited settings. Lipodystrophy is common and options for switching ART regimen are limited; this situation can lead to patients' poor adherence and antiretroviral resistance. Treatment interruption (TI) in patients with high CD4 cell counts, lipodystrophy, and limited options may be an alternative in resource-limited settings. This study aimed to determine time to resume ART after TI and predictors for early resumption of ART in a resource-limited setting.MethodsA prospective study was conducted in January 2005 to December 2006 and enrolled HIV-infected patients with HIV-1 RNA <50 copies/mL, CD4 > 350 cells/mm3, and willing to interrupt ART. CD4 cell count, HIV-1 RNA, lipid profile, and lipodystrophy were assessed at baseline and every 3 months. ART was resumed when CD4 declined to <250 cells/mm3 or developed HIV-related symptoms. Patients were grouped based on ART regimens [NNRTI or protease inhibitor (PI)] prior to TI.ResultsThere were 99 patients, 85 in NNRTI group and 14 in PI group. Mean age was 40.6 years; 46% were males. Median duration of ART was 47 months. Median nadir CD4 and baseline CD4 were 151 and 535 cells/mm3, respectively. Median CD4 change at 3 months after TI were -259 (NNRTI) and -105 (PI) cells/mm3 (p = 0.038). At 13-month median follow-up, there was no AIDS-defining illness; 38% (NNRTI) and 29% (PI) of patients developed HIV-related symptoms. ART was resumed in 51% (NNRTI) and 36% (PI) of patients (p = 0.022). By Kaplan-Meier analysis, median time to resume ART was 5.5 (NNRTI) and 14.2 (PI) months (log rank test, p = 0.026). By Cox's regression analysis, NNRTI-based ART (HR 4.9; 95%CI, 1.5–16.3), nadir CD4 <100 cells/mm3 (HR 2.7; 95%CI 1.4–5.3) and baseline CD4 <500 cells/mm3 (HR 1.6; 95%CI, 1.2–3.1) were predictors for early ART resumption.ConclusionTI of NNRTI-based ART leads to rapid CD4 decline and high probability of early ART resumption and should be avoided. It is necessary to scale-up the options for HIV-infected patients with lipodystrophy in resource-limited settings.

Transmitted drug‐resistant HIV‐1 in primary HIV‐1 infection; incidence, evolution and impact on response to antiretroviral therapy

The aim of the study was to determine the incidence and persistence of transmitted drug-resistant HIV-1 in an incident cohort between 2000 and 2004, and to investigate the impact of transmitted drug-resistant HIV-1 on the response to antiretroviral therapy (ART). A prospective, nonrandomized study was carried out on 140 individuals identified with primary HIV-1 infection (PHI). PHI was defined as an HIV-positive antibody test with an HIV antibody-negative result in the prior 6 months (n = 69); positive HIV DNA in the absence of antibody (n = 30); an evolving titre positive HIV antibody test (n = 23), or an incident 'detuned' assay (B clade viruses only) (n = 18). Genotypic resistance testing was performed at baseline, following ART and annually over a 4-year period. The prevalence of transmitted drug-resistant HIV-1 infection between January 2000 and June 2004 was nine in 140 (6.0%) and the annual incidence was stable. Seven of these nine patients had a single point mutation conferring single-class drug resistance and the other two patients had multiple mutations conferring multiclass drug resistance (MDR). In eight of the nine cases, mutations conferring drug resistance persisted for more than 12 months off therapy. In contrast to transmitted MDR HIV-1, the virological response to initial ART and CD4 decline were comparable in those with wild-type virus, virus with 'polymorphisms' (secondary mutations) and virus with single drug-resistance mutations. The incidence of transmitted drug-resistant HIV remained stable and low over a 4-year period. Although MDR remains rare, its presence significantly affects the response to first-line ART, predisposes towards the accumulation of new resistance mutations and is associated with a more rapid CD4 decline.

HIV in central nervous system and behavioral development

To determine which route of inoculation produced consistent and frequent HIV infection in the central nervous system (CNS) and alterations in cognitive and motor development in infant macaques. Infant macaques (Macaca nemestrina) were inoculated with the highly pathogenic strain HIV-2287 intravenously (n = 3) or intrathecally (n = 3). Uninfected infants were evaluated as controls. Disease progression was evaluated by virological assessment of blood and cerebral spinal fluid (CSF), CD4 T cell count in blood, and quinolinic acid levels in CSF (a surrogate marker of neuronal cell damage). The effect of HIV infection on cognitive and motor development in infants was monitored during the 6-month study. Either route of HIV-2287 inoculation produced detectable viral RNA in CSF and productive infection in blood. Detection of virus in CSF paralleled a rise in quinolinic acid levels. All HIV-infected infants experienced a severe and rapid decline in CD4 T cell counts by 10 weeks after viral infection. HIV-infected infants, particularly those infected by the intravenous route, exhibited delays in reaching cognitive and motor milestones, which paralleled neuropathological changes. The HIV-2287 infant model produced a high incidence of viral infection in the CNS regardless of the route of inoculation. Significant alteration in neurobehavioral development was observed in HIV-infected infants, and this measure was significantly impaired particularly in infants infected by the intravenous route. These data, coupled with the ability to detect viral RNA and changes in quinolinic acid levels in CSF, may allow quantitative evaluation of drug and immune candidates for treating neurological effects of AIDS.

Clinical and immunological impact of HIV envelope V3 sequence variation after starting initial triple antiretroviral therapy.

The HIV-1 envelope third variable loop (V3 loop) is an important determinant of viral phenotype and co-receptor usage. We wished to determine the impact of specific V3 genotypes associated with viral phenotype and co-receptor usage on response to initial triple antiretroviral therapy. Pre-therapy plasma samples from the HOMER cohort of 1191 antiretroviral-naive, HIV-infected adults who initiated triple therapy in British Columbia, Canada between August 1996 and September 1999 were genotyped for V3 loop sequence. V3 sequences were dichotomized by the presence or absence of positively charged residues at codons 11 and/or 25 (an '11/25' genotype). Neural network (NN) and Position Specific Scoring Matrix (PSSM) approaches were used as alternative V3 sequence interpretation methods. The association of V3 genotypes with clinical endpoints was assessed over a median of 43 months of follow up. One-hundred and eighteen (10.9%) of the 1085 isolates successfully genotyped for V3 displayed the 11/25 genotype. In multivariate analyses, this genotype was associated with a more rapid CD4 decline [risk ratio, (RR), 1.38; P = 0.012] and earlier mortality (RR, 1.70; P = 0.027), despite comparable viral load suppression below 500 HIV RNA copies/ml. We observed no influence of the 11/25 genotype on time to viral rebound or the development of drug resistance. PSSM-based sequence categories were similarly predictive of outcomes. NN sequence categories were not associated with any endpoints. The 11/25 genotype of the HIV V3 loop is an independent predictor of poor immunological response and more rapid mortality even after starting triple antiretroviral therapy. These results may prove to be useful for the clinical management of HIV-infected individuals.

Higher levels of IL-18 circulate during primary infection of monkeys with a pathogenic SHIV than with a nonpathogenic SHIV

We have monitored kinetics of peripheral blood Interleukin (IL)-18 level, viral RNA load, and CD4 + T cell counts in cynomolgus and rhesus macaques following infections of various simian/human immunodeficiency viruses (SHIVs) causing differential pathogenicity. Infections of cynomolgus and rhesus macaques with pathogenic SHIVs-C2/1 and -89.6PD, respectively, induced high levels of plasma IL-18 (0.1–1 ng/ml) and enhanced apoptosis of peripheral blood T cells during primary viremia, along with a rapid decline of CD4 + T cells and a high level of set point viral load after primary viremia (six of six cases). In contrast, infections of cynomolgus macaques with nonpathogenic SHIVs-TH09V3 and -MD14 did not cause such IL-18 elevation, showing no decline of CD4 + T cells and no or low viral set point level following primary viremia (three of three cases). Thus, the elevation of circulating IL-18 level during primary viral infection can be a good indicator of an active pathogenic viral infection. However, the role of increased IL-18 remains to be elucidated and needs further investigation.

In vivo evolution of human immunodeficiency virus type 1 toward increased pathogenicity through CXCR4-mediated killing of uninfected CD4 T cells.

The destruction of the immune system by progressive loss of CD4 T cells is the hallmark of AIDS. CCR5-dependent (R5) human immunodeficiency virus type 1 (HIV-1) isolates predominate in the early, asymptomatic stages of HIV-1 infection, while CXCR4-dependent (X4) isolates typically emerge at later stages, frequently coinciding with a rapid decline in CD4 T cells. Lymphocyte killing in vivo primarily occurs through apoptosis, but the importance of apoptosis of HIV-1-infected cells relative to apoptosis of uninfected bystander cells is controversial. Here we show that in human lymphoid tissues ex vivo, apoptosis of uninfected bystander CD4 T cells is a major mechanism of lymphocyte depletion caused by X4 HIV-1 strains but is only a minor mechanism of depletion by R5 strains. Further, X4 HIV-1-induced bystander apoptosis requires the interaction of the viral envelope glycoprotein gp120 with the CXCR4 coreceptor on CD4 T cells. These results emphasize the contribution of bystander apoptosis to HIV-1 cytotoxicity and suggest that in association with a coreceptor switch in HIV disease, T-cell killing evolves from an infection-restricted stage to generalized toxicity that involves a high degree of bystander apoptosis.

HIV-1 Infection in Individuals With the CCR5-Δ32/Δ32 Genotype: Acquisition of Syncytium-Inducing Virus at Seroconversion

Homozygosity for the 32 base-pair deletion (Delta32/Delta32) in the CCR5 coreceptor gene is associated with incomplete HIV-1 resistance. Six HIV-1-infected Delta32/Delta32 patients have been reported. We report 2 additional Delta32/Delta32-infected individuals, among 106 seroconverters in a vaccine preparedness study. Like the previous 6, these individuals experienced rapid CD4 decline. However, taken together, the 8 patients have neither uniformly high virus load nor rapid progression to AIDS. We obtained five virus isolates from 1 patient at 5, 6, 7, 10, and 12 months after the estimated time of infection. The earliest isolate exhibits the syncytium-inducing (SI) phenotype and exclusive use of the CXCR4 coreceptor, suggesting acquisition of HIV-1 through this coreceptor. Of the remaining 104 seroconverters, 8 were CCR5-Delta32/+ and 96 were CCR5-+/+. Three CCR5-+/+ seroconverters who showed the uncommon pattern of early SI virus and rapid CD4 decline had uniformly high viral load and more heterogeneous coreceptor usage. These results further support the conclusion that Delta32-mediated resistance is incomplete and is associated with acquisition of exclusively-X4 variants of HIV-1. The pathogenic potential of these viruses may be different from late-stage X4 virus or early X4 virus acquired by individuals with other CCR5 genotypes.