Plasma Viral RNA Levels Research Articles

The HIV Restriction Factor Profile in the Brain Is Associated with the Clinical Status and Viral Quantities.

HIV-encoded DNA, RNA and proteins persist in the brain despite effective antiretroviral therapy (ART), with undetectable plasma and cerebrospinal fluid viral RNA levels, often in association with neurocognitive impairments. Although the determinants of HIV persistence have garnered attention, the expression and regulation of antiretroviral host restriction factors (RFs) in the brain for HIV and SIV remain unknown. We investigated the transcriptomic profile of antiretroviral RF genes by RNA-sequencing with confirmation by qRT-PCR in the cerebral cortex of people who are uninfected (HIV[-]), those who are HIV-infected without pre-mortem brain disease (HIV[+]), those who are HIV-infected with neurocognitive disorders (HIV[+]/HAND) and those with neurocognitive disorders with encephalitis (HIV[+]/HIVE). We observed significant increases in RF expression in the brains of HIV[+]/HIVE in association with the brain viral load. Machine learning techniques identified MAN1B1 as a key gene that distinguished the HIV[+] group from the HIV[+] groups with HAND. Analyses of SIV-associated RFs in brains from SIV-infected Chinese rhesus macaques with different ART regimens revealed diminished RF expression among ART-exposed SIV-infected animals, although ART interruption resulted in an induced expression of several RF genes including OAS3, RNASEL, MX2 and MAN1B1. Thus, the brain displays a distinct expression profile of RFs that is associated with the neurological status as well as the brain viral burden. Moreover, ART interruption can influence the brain's RF profile, which might contribute to disease outcomes.

Functional MAIT Cells Are Associated With Reduced Simian-Human Immunodeficiency Virus Infection.

Mucosa-associated invariant T (MAIT) cells are recently characterized as a novel subset of innate-like T cells that recognize microbial metabolites as presented by the MHC-1b-related protein MR1. The significance of MAIT cells in anti-bacterial defense is well-understood but not clear in viral infections such as SIV/HIV infection. Here we studied the phenotype, distribution, and function of MAIT cells and their association with plasma viral levels during chronic SHIV infection in rhesus macaques (RM). Two groups of healthy and chronic SHIV-infected macaques were characterized for MAIT cells in blood and mucosal tissues. Similar to human, we found a significant fraction of macaque T cells co-expressing MAIT cell markers CD161 and TCRVα-7.2 that correlated directly with macaque MR1 tetramer. These cells displayed memory phenotype and expressed high levels of IL-18R, CCR6, CD28, and CD95. During chronic infection, the frequency of MAIT cells are enriched in the blood but unaltered in the rectum; both blood and rectal MAIT cells displayed higher proliferative and cytotoxic phenotype post-SHIV infection. The frequency of MAIT cells in blood and rectum correlated inversely with plasma viral RNA levels and correlated directly with total CD4 T cells. MAIT cells respond to microbial products during chronic SHIV infection and correlated positively with serum immunoreactivity to flagellin levels. Tissue distribution analysis of MAIT cells during chronic infection showed significant enrichment in the non-lymphoid tissues (lung, rectum, and liver) compared to lymphoid tissues (spleen and LN), with higher levels of tissue-resident markers CD69 and CD103. Exogenous in vitro cytokine treatments during chronic SHIV infection revealed that IL-7 is important for the proliferation of MAIT cells, but IL-12 and IL-18 are important for their cytolytic function. Overall our results demonstrated that MAIT cells are enriched in blood but unaltered in the rectum during chronic SHIV infection, which displayed proliferative and functional phenotype that inversely correlated with SHIV plasma viral RNA levels. Treatment such as combined cytokine treatments could be beneficial for enhancing functional MAIT cells during chronic HIV infection in vivo.

Accumulation of CXCR5+ NK cells during chronic SHIV infection is associated with enhanced viral control

Abstract Natural Killer (NK) cells play an essential role in antiviral immunity, however knowledge pertaining to their function in lymphoid organs during chronic HIV infection is not clearly elucidated. Lymph node (LN) follicles constitute major reservoir sites for HIV persistence. Cure strategies could benefit from the LN CXCR5+ NK cells able to access/eliminate viral reservoirs. Here we studied the phenotype, distribution and function of CXCR5+ NK cells in the LN of SHIV naive and chronic SHIV-infected (>14 weeks PI) rhesus macaques (RM) and its association with plasma viral RNA levels. We found that prior to infection, a significant proportion of NK cells (~15%) expressed CXCR5. Following infection, the frequency of CXCR5+ NK cells was significantly higher in chronic SHIV-infected RM. Phenotypically CXCR5+ NK cells express higher levels of CD32a and CD16 compared to CXCR5− cells, which might be important for ADCC function. RNA expression profiling of sorted CXCR5+ and CXCR5− NK cells from LNs of chronic SHIV-infected RM revealed that CXCR5+ cells are activated and express increased levels of cytolytic markers (perforin, granzyme-B, granulysin and CD107a), suggesting that these cells have a higher capacity to kill. Gene set enrichment analysis showed elevated expression in CXCR5+ cells of transcripts associated with cell activation, TNF-alpha, Interferon signaling and apoptosis. Importantly, the higher frequency of CXCR5+ NK cells was associated with lower SHIV plasma viral RNA levels and lower germinal center Tfh cells. Thus these data suggest that CXCR5+ NK cells could play an important role in controlling chronic SHIV infection. HIV cure strategies should focus on inducing CXCR5+ NK cells that may contribute to sustained viral remission.

Human immunodeficiency virus type 2 (HIV-2) dynamics and whole genome deep sequence analysis in Mauritian-origin cynomolgus macaques (Macaca fascicularis)

Human immunodeficiency virus type 2 (HIV-2) is a pathogenic human retrovirus with a distinct natural history and lineage derivation from pandemic HIV-1. HIV-2 infections in humans are the result of zoonotic transmission from sooty mangabey monkeys naturally infected with SIVsm. Unlike HIV-1, HIV-2 infects other non-human primate species, including baboons and macaques. We determined the infectivity and infection kinetics of a Gambian-origin HIV-2 isolate HIV-2SBL6669 strain in Mauritian-derived cynomolgus macaques (MCM) in the context of a heterologous superinfection resistance study. The ability of HIV-2 to replicate in unvaccinated MCM with limited host genetic MHC and TRIM5 spectrum was determined where the kinetics of plasma HIV-2 RNA mimic the phenotypic response typically observed in HIV-2-infected humans. HIV-2SBL669 replication is not completely restricted in this species and may establish a persistent infection. This is determined by moderate peak viral loads (105–6 log10 HIV-2 RNA copies/ml) controlling to a low level determined by qRT-PCR and detectable in-situ hybridisation signals in lymphoid tissue 20 weeks after challenge. In MCM vaccinated for 20 weeks with an attenuated SIV, we observed high levels of superinfection resistance as determined by virus-specific PCR analysis of tissues and low total plasma viral RNA levels in vaccinates compared to unvaccinated HIV-2 controls. Recovery of whole viral genome and next generation sequence analysis of challenge controls, including low-level breakthrough variants characterises viral challenge and vaccine-escape viruses. HIV-2 in cynomolgus macaques recapitulates many of the features of HIV-2 infections in humans.

The effect of freeze-dried Carica papaya leaf juice treatment on NS1 and viremia levels in dengue fever mice model

BackgroundCarica papaya leaf juice (CPLJ) was well known for its thrombocytosis activity in rodents and dengue patients. However, the effect of CPLJ treatment on other parameters that could contribute to dengue pathogenesis such as nonstructural protein 1 (NS1) production and viremia level have never been highlighted in any clinical and in vivo studies. The aim of this study is to investigate the effect of freeze-dried CPLJ treatment on NS1 and viremia levels of dengue fever mouse model.MethodsThe dengue infection in mouse model was established by inoculation of non-mouse adapted New Guinea C strain dengue virus (DEN-2) in AG129 mice. The freeze-dried CPLJ compounds were identified by Ultra-High Performance Liquid Chromatography High Resolution Accurate Mass Spectrometry analysis. The infected AG129 mice were orally treated with 500 mg/kg/day and 1000 mg/kg/day of freeze-dried CPLJ, starting on day 1 post infection for 3 consecutive days. The blood samples were collected from submandibular vein for plasma NS1 assay and quantitation of viral RNA level by quantitative reverse transcription PCR.ResultsThe AG129 mice infected with dengue virus showed marked increase in the production of plasma NS1, which was detectable on day 1 post infection, peaked on day 3 post-infection and started to decline from day 5 post infection. The infection also caused splenomegaly. Twenty-four compounds were identified in the freeze-dried CPLJ. Oral treatment with 500 mg/kg/day and 1000 mg/kg/day of freeze-dried CPLJ did not affect the plasma NS1 and dengue viral RNA levels. However, the morbidity level of infected AG129 mice were slightly decreased when treated with freeze-dried CPLJ.ConclusionOral treatment of 500 mg/kg/day and 1000 mg/kg/day of freeze-dried CPLJ at the onset of viremia did not affect the plasma NS1 and viral RNA levels in AG129 mice infected with non-mouse adapted New Guinea C strain dengue virus.

MAIT cells (CD8+CD161++TCR7.2++) are functionally impaired during chronic SHIV infection.

Abstract Mucosa-associated invariant T-cells (MAIT) are abundant in humans and recognize bacterial ligands. Here, we have studied the distribution and function of MAIT cells during chronic SHIV infection using rhesus macaques (RM). Two groups of RM, healthy and SHIV infected were studied. lymphocytes from various tissues were analysed for MAIT (TCR7.2++ CD161++) cells using multicolor flow cytometry and characterized for their distribution, phenotype and function during chronic SHIV infection. Similar to human, we found significant fraction of (~2%) RM CD8 T cells co-express MAIT cell markers TCR7.2, CD161, IL-18R, CCR6 and display central memory (CCR7+CD45RA−) phenotype. The frequency of MAIT cells were decreased during chronic SHIV infection and tissue analysis showed a significant enrichment of MAIT cells in liver (~8%) and BAL (3%) than in blood (1%), spleen(0.5%), lymph node(0.13%) and gut (0.2%). Importantly, during chronic SHIV infection more than 80% of MAIT cells expressed T cell exhaustion marker PD-1 in blood and the level of expression was higher (>95%) in tissue resident CD69+MAIT cells. These cells lack proliferating capacity (Ki-67) and cytokine production (IFN- g and IL-17) in the blood, suggesting their functional impairment. The preserved blood and gut MAIT cells correlate inversely with plasma viral RNA levels and associate directly with gut CD4 T cell levels, suggesting that CD4 help maintains MAIT cell frequencies in the gut. These data demonstrate that MAIT cells are decreased in blood and are functionally exhausted during chronic SHIV infection. Future studies focused on blocking the PD-1 pathway to retrive MAIT cell exhaustion during chronic SHIV/HIV infection may yield therapeutic benefit to HIV/SHIV infection.

427. In Vivo Inhibition of HIV-1 in NSG Mice After Transduction of Primary Human T Cells with CXCR4 Conjugated to an HR2 Peptide

Introduction: We previously reported that a 34 a.a. peptide from the C-terminal heptad repeat-2 domain (HR2) of HIV-1 gp41 (C34) when fused to the N-terminus of CXCR4 (C34-X4) inhibits HIV-1 infection in transduced cells in vitro. This construct provided protection irrespective of HIV viral tropism (i.e., C34-X4 could inhibit R5, X4 or dual-tropic isolates).Methods: To assess the ability of C34-conjugated coreceptor to exert transdominant inhibition of R5- and X4-tropic HIV-1 in vivo, C34-X4 was transduced using a lentiviral vector into CD3/CD28-stimulated primary human CD4+ T cells with GFP-transduced T cells serving as a control. Cells were infused in NOD-scid-gamma (NSG) mice either undiluted or mixed (25% of total cells) with untransduced T cells. After 21 days, mice were challenged i.v. with R5 (US1, Clade B) and X4 (CMU02 Clade A/E) tropic HIV-1 and infection assessed by plasma viral RNA levels and by survival of C34-X4-expressing cells.Results: In NSG mice receiving C34-X4 transduced cells, at Day 18 there was significant expansion of the CD4+/CD45+/CXCR4+ T cell population, but not of GFP control cells (p=0.005). Viral loads were significantly lower in mice receiving C34-X4 transduced cells compared to those receiving GFP-transduced cells (p=0.047). At necropsy (Day 28) in splenocytes there was an approximate 2 log increase in the number of CD4 T cells in mice receiving C34-X4 transduced cells (p=0.001).Conclusion: These studies demonstrate that the C34 peptide conjugated CXCR4 confers resistance of CD4 T cells to HIV-1 infection irrespective of viral tropism, providing a proof of concept that targeting an HR2 inhibitory peptide to a coreceptor exerts potent transdominant inhibition of HIV-1 in vivo. This novel genetic approach to confer HIV resistance to CD4 T cells, coupled with high barriers for viral resistance to C34-coreceptors, may provide a novel approach for HIV control in humans.

Drug resistance and plasma viral RNA level after ineffective use of oral pre-exposure prophylaxis in women.

Pre-exposure prophylaxis (PrEP) with daily oral emtricitabine (FTC)/tenofovir disoproxil fumarate may select for drug resistance if there is low adherence. Plasma viral HIV-1 RNA level, CD4+ T-cell counts, and drug resistance were evaluated among seroconverting women in the FEM-PrEP trial (clinicaltrials.gov NCT00625404) using standard clinical tests, allele-specific PCR (ASPCR), and by deep sequencing. Tenofovir, FTC, and their intracellular metabolites were measured in plasma and cells. There was no difference in plasma HIV-1 RNA level or CD4+ cell count among seroconverters in the active arm versus those receiving placebo. Tenofovir resistance was not observed. FTC resistance was detected using clinical assays in five seroconverters (four in the active arm and one in the placebo arm); two in the active arm occurred among women having moderate concentrations of PrEP drugs in the blood. The first evidence of infection occurred at the first postenrollment visit in three of the four with FTC resistance, although none had detectable viral nucleic acids at enrollment. FTC-resistant minor variants were detected in an additional four seroconverters (one in the active arm and three in the placebo arm). Drug resistance detected during ineffective PrEP use had characteristics suggesting transmitted infection or incubating infection prior to starting PrEP.

Cytotoxic capacity of SIV-specific CD8(+) T cells against primary autologous targets correlates with immune control in SIV-infected rhesus macaques.

Although the study of non-human primates has resulted in important advances for understanding HIV-specific immunity, a clear correlate of immune control over simian immunodeficiency virus (SIV) replication has not been found to date. In this study, CD8+ T-cell cytotoxic capacity was examined to determine whether this function is a correlate of immune control in the rhesus macaque (RM) SIV infection model as has been suggested in chronic HIV infection. SIVmac251-infected human reverse transcriptase (hTERT)-transduced CD4+ T-cell clone targets were co-incubated with autologous macaque effector cells to measure infected CD4+ T-cell elimination (ICE). Twenty-three SIV-infected rhesus macaques with widely varying plasma viral RNA levels were evaluated in a blinded fashion. Nineteen of 23 subjects (83%) were correctly classified as long-term nonprogressor/elite controller (LTNP/EC), slow progressor, progressor or SIV-negative rhesus macaques based on measurements of ICE (weighted Kappa 0.75). LTNP/EC had higher median ICE than progressors (67.3% [22.0–91.7%] vs. 23.7% [0.0–58.0%], p = 0.002). In addition, significant correlations between ICE and viral load (r = −0.57, p = 0.01), and between granzyme B delivery and ICE (r = 0.89, p<0.001) were observed. Furthermore, the CD8+ T cells of LTNP/EC exhibited higher per-cell cytotoxic capacity than those of progressors (p = 0.004). These findings support that greater lytic granule loading of virus-specific CD8+ T cells and efficient delivery of active granzyme B to SIV-infected targets are associated with superior control of SIV infection in rhesus macaques, consistent with observations of HIV infection in humans. Therefore, such measurements appear to represent a correlate of control of viral replication in chronic SIV infection and their role as predictors of immunologic control in the vaccine setting should be evaluated.

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Low-Dose Penile SIVmac251 Exposure of Rhesus Macaques Infected with Adenovirus Type 5 (Ad5) and Then Immunized with a Replication-Defective Ad5-Based SIV gag/pol/nef Vaccine Recapitulates the Results of the Phase IIb Step Trial of a Similar HIV-1 Vaccine

The Step Trial showed that the MRKAd5 HIV-1 subtype B Gag/Pol/Nef vaccine did not protect men from HIV infection or reduce setpoint plasma viral RNA (vRNA) levels but, unexpectedly, it did modestly enhance susceptibility to HIV infection in adenovirus type 5 (Ad5)-seropositive, uncircumcised men. As part of the process to understand the results of the Step Trial, we designed a study to determine whether rhesus macaques chronically infected with a host-range mutant Ad5 (Ad5hr) and then immunized with a replication defective Ad5 SIVmac239 Gag/Pol/Nef vaccine were more resistant or susceptible to SIV infection than unimmunized rhesus macaques challenged with a series of escalating dose penile exposures to SIVmac 251. The Ad5 SIV vaccine induced CD8(+) T cell responses in 70% of the monkeys, which is similar to the proportion of humans that responded to the vaccine in the Step Trial. However, the vaccine did not protect vaccinated animals from penile SIV challenge. At the lowest SIV exposure dose (10(3) 50% tissue culture infective doses), 2 of 9 Ad5-seropositive animals immunized with the Ad5 SIV vaccine became infected compared to 0 of 34 animals infected in the other animal groups (naive animals, Ad5-seropositive animals immunized with the empty Ad5 vector, Ad5-seronegative animals immunized with the Ad5 SIV vaccine, and Ad5-seronegative animals immunized with the empty Ad5 vector). Penile exposure to more concentrated virus inocula produced similar rates of infection in all animal groups. Although setpoint viral loads were unaffected in Step vaccinees, the Ad5 SIV-immunized animals had significantly lower acute-phase plasma vRNA levels compared to unimmunized animals. Thus, the results of the nonhuman primate (NHP) study described here recapitulate the lack of protection against HIV acquisition seen in the Step Trial and suggest a greater risk of infection in the Ad5-seropositive animals immunized with the Ad5 SIV vaccine. Further studies are necessary to confirm the enhancement of virus acquisition and to discern associated mechanisms.

Antibody-Dependent Cell-Mediated Cytotoxicity in Simian Immunodeficiency Virus-Infected Rhesus Monkeys

With the recent demonstration in the RV144 Thai trial that a vaccine regimen that does not elicit neutralizing antibodies or cytotoxic T lymphocytes may confer protection against human immunodeficiency virus type 1 (HIV-1) infection, attention has turned to nonneutralizing antibodies as a possible mechanism of vaccine protection. In the current study, we evaluated the kinetics of the antibody-dependent cell-mediated cytotoxicity (ADCC) response during acute and chronic SIVmac251 infection of rhesus monkeys. We first adapted a flow cytometry-based ADCC assay, evaluating the use of different target cells as well as different strategies for quantitation of activated natural killer (NK) cells. We found that the use of SIVmac251 Env gp130-coated target cells facilitates analyses of ADCC activity with a higher degree of sensitivity than the use of simian immunodeficiency virus (SIV)-infected target cells; however, the kinetics of the measured responses were the same using these different target cells. By comparing NK cell expression of CD107a with NK cell expression of other cytokines or chemokine molecules, we found that measuring CD107a expression is sufficient for evaluating the anti-SIV function of NK cells. We also showed that ADCC responses can be detected as early as 3 weeks after SIVmac251 infection and that the magnitude of this antibody response is inversely associated with plasma viral RNA levels in animals with moderate to high levels of viral replication. However, we also demonstrated an association between NK cell-mediated ADCC responses and the amount of SIVmac251 gp140 binding antibody that developed after viral infection. This final observation raises the possibility that the antibodies that mediate ADCC are a subset of the antibodies detected in a binding assay and arise within weeks of infection.

Dendritic Cell–Mediated HIV-1 Infection of T Cells Demonstrates a Direct Relationship to Plasma Viral RNA Levels

To examine the relationship between infectivity of HIV-1 variants in dendritic cell (DC)-mediated in trans infection of T cells and plasma viral RNA levels in infected subjects. HIV-1 was isolated from peripheral blood mononuclear cells of chronically infected individuals, typed for coreceptor usage, and viral replication were examined in monocyte-derived DCs-peripheral blood lymphocytes cocultures. The rate of p24 antigen production during the logarithmic phase of viral replication was determined by enzyme-linked immunosorbent assay. Additionally, nef variants were cloned and expressed in trans with a HIV luciferase vector and CCR5-tropic HIV-1 envelope, and infectivity was measured in DC-mediated capture-transfer assays. Replication capacity of HIV-1 viral CCR5-tropic isolates in monocyte-derived dendritic cells-peripheral blood lymphocytes cocultures was linearly associated with the plasma viral RNA levels in a cohort of HIV-1-infected individuals exhibiting an inverse relationship between plasma viral RNA and CD4 cell count. Furthermore, infectivity activity of nef variants in context of DC-mediated enhanced infection of T cells also showed a linear relationship to plasma viral RNA levels. These results illustrate that replication capacity of HIV-1 in DC T-cell cultures is a significant determinant of plasma viral RNA level. The data suggest that adaptation of HIV-1 to DC interactions with T cells influences the level of viral replication in the host.

Depo-provera treatment does not abrogate protection from intravenous SIV challenge in female macaques immunized with an attenuated AIDS virus.

BackgroundIn a previous study, progesterone treatment of female monkeys immunized with live, attenuated SHIV89.6 abrogated the generally consistent protection from vaginal simian immunodeficiency virus (SIV) challenge. The mechanisms responsible for the loss of protection remain to be defined. The objective of the present study was to determine whether Depo-Provera® administration alters protection from intravenous SIV challenge in SHIV-immunized female macaques.Methods and FindingsTwo groups of female macaques were immunized with attenuated SHIV89.6 and then challenged intravenously with SIVmac239. Four weeks before challenge, one animal group was treated with Depo-Provera®, a commonly used injectable contraceptive progestin. As expected, SHIV-immunized monkeys had significantly lower peak and set-point plasma viral RNA levels compared to naïve controls, but in contrast to previously published findings with vaginal SIV challenge, the Depo-Provera® SHIV-immunized animals controlled SIV replication to a similar, or even slightly greater, degree than did the untreated SHIV-immunized animals. Control of viral replication from week 4 to week 20 after challenge was more consistent in the progesterone-treated, SHIV-immunized animals than in untreated, SHIV-immunized animals. Although levels of interferon-γ production were similar, the SIV-specific CD8+ T cells of progesterone-treated animals expressed more functions than the anti-viral CD8+ T cells from untreated animals.ConclusionsDepo-Provera® did not diminish the control of viral replication after intravenous SIV challenge in female macaques immunized with a live-attenuated lentivirus. This result contrasts with the previously reported effect of Depo-Provera® on protection from vaginal SIV challenge and strongly implies that the decreased protection from vaginal challenge is due to effects of progesterone on the genital tract rather than to systemic effects. Further, these results demonstrate that the effects of hormonal contraceptives on vaccine efficacy need to be considered in the context of testing and use of an AIDS vaccine.

The impact of AIDS diagnoses on long-term neurocognitive and psychiatric outcomes of surviving adolescents with perinatally acquired HIV

To explore the association between previous severe HIV disease, defined as past Centers for Disease Control and Prevention class C diagnosis, and neurocognitive and psychiatric outcomes in long-term survivors of perinatally acquired HIV. A retrospective cohort study of perinatally HIV-infected adolescents receiving outpatient care at a single site. Comparisons were made between those with and without class C diagnoses. Eighty-one patients formed the study group, 47% were females and 72% were African-American. Median patient age was 15 years (interquartile range 13-17). Of the study group, 47% had a past class C diagnosis. The median age at class C diagnosis was 3.1 years (interquartile range 0.9-8.1). There were no significant differences between the groups with respect to most recent CD4(+) cell percentage or plasma viral RNA level. Class C patients were more likely to have a history of psychiatric diagnosis [odds ratio 2.6; 95% confidence interval (CI) 1.1-6.3], psychiatric hospitalization (odds ratio 4.8; 95% CI 1.2-17.4), or learning disability (odds ratio 4.5; 95% CI 1.7-11.4). There was a significant difference in full-scale intelligence quotient between the groups (adjusted linear regression coefficient -11.7; 95% CI -17.9 to 5.5). After adjusting for age at antiretroviral therapy initiation, the associations between class C diagnosis and lower full-scale intelligence quotient, learning disorders, and psychiatric diagnoses remained significant. A distant history of AIDS diagnosis was associated with an increased risk of neurocognitive and psychiatric impairment in adolescents with perinatally acquired HIV. Further research should help delineate if early treatment, possibly soon after birth and definitely prior to AIDS diagnosis, might lead to improved outcomes.

Enhanced Antibody Responses Elicited by a CpG Adjuvant Do Not Improve the Protective Effect of an Aldrithiol-2-Inactivated Simian Immunodeficiency Virus Therapeutic AIDS Vaccine

The potential benefit of using unmethylated CpG oligoribodeoxynucleotides (ODN) as an adjuvant in a therapeutic simian immunodeficiency virus (SIV) vaccine consisting of AT2-inactivated SIVmac239 was evaluated in SIV-infected rhesus macaques receiving antiretroviral therapy (ART). We hypothesized that using CpG ODN as an adjuvant in therapeutic vaccination would enhance SIV-specific immune responses and suppress SIV replication after ART was stopped. To test our hypothesis, we immunized chronically SIV-infected rhesus macaques receiving ART with one of the following therapeutic vaccines: (i) AT2-inactivated SIVmac239, (ii) CpG10103 plus AT2-inactivated SIVmac239, (iii) CpG10103, and (iv) saline. While immunization with CpG plus AT2-SIVmac239 significantly increased SIV-specific immunoglobulin G (IgG) antibody titers, the mean plasma viral RNA (vRNA) level in these animals after ART did not differ from those of saline-treated animals. The AT2-inactivated SIVmac239-immunized animal group had a significantly higher mean SIV-specific gamma interferon T-cell response after three immunizations and lower plasma vRNA levels for 6 weeks after ART was withdrawn compared to the saline-treated animal group. Compared to the saline control group, the animal group treated with CpG alone had a significantly higher mean SIV-specific lymphocyte proliferation index and a higher rate of plasma vRNA rebound after ART. These results demonstrate that while the use of CpG as an adjuvant enhances SIV-specific antibody responses, this does not improve the control of SIV replication after ART is stopped. The lack of benefit may be related to the high levels of SIV-specific lymphocyte proliferation in the CpG adjuvant group.

African Non Human Primates Infected by SIV - Why Dont they Get Sick? Lessons from Studies on the Early Phase of Non-Pathogenic SIV Infection

African non human primates are natural hosts of SIV. The infection is generally non-pathogenic despite high steady-state levels of plasma viral RNA that in HIV-1 and SIVmac infections are associated with progression towards AIDS. The viral loads in the gut also are as high as in pathogenic HIV-1/SIVmac infections; but replication levels are lower in peripheral lymph nodes of chronically infected African green monkeys. There is a transient loss of CD4(+) T cells in the blood in SIVagm and SIVsm infections and an early dramatic and more persistent decrease in the gut. Although SIV in natural hosts is thus cytopathic, the continuous viral replication is not associated with immunopathology. T CD4(+) cells in blood, lymph nodes and gut manifest no or little increase of cell-death by apoptosis. The lymph node and gut architecture is not disrupted. The most striking difference between non-pathogenic SIV and pathogenic HIV-1/SIVmac infections is the lack of chronic T cell activation. Several studies are currently in progress to determine which factors are involved in the maintenance of the low activation level in the non-pathogenic SIV infections. There are two ways in which this could be achieved: (i) a lack of immune activation induction or (ii) an active downregulation of the immune activation. The arguments in favor of each of these two possible ways of immune activation control will be discussed in view of the most recent data in the literature. A particular focus is put on data on the innate immune system and the timing of induction of immunosuppressive mediators during the early phase of SIV infection.

Association between endogenous feline leukemia virus loads and exogenous feline leukemia virus infection in domestic cats

Recently, we demonstrated that endogenous feline leukemia virus (enFeLV) loads may vary among cats of different populations and that FeLV-infected cats have higher enFeLV loads than uninfected cats. Thus, we hypothesized that enFeLV might influence the pathogenesis and outcome of FeLV infection. No significant difference in the infection outcome (regressive versus progressive infection) was observed between groups of cats with high or low enFeLV loads following FeLV-A challenge. However, cats with high enFeLV loads showed higher viral replication (plasma viral RNA and p27 antigen levels) than cats with low enFeLV loads in the early phase of the infection. The enFeLV transcription level varied at different time points, but no clear-cut pattern was observed. In conclusion, our results demonstrated an association between enFeLV loads and FeLV replication but not outcome of infection. enFeLV should be considered as an important confounder in experimental FeLV infection or vaccination studies.

Depo‐Provera abrogates attenuated lentivirus‐induced protection in male rhesus macaques challenged intravenously with pathogenic SIVmac239

Progesterone administration prior to intravaginal challenge with pathogenic SIVmac239 decreases the protective efficacy of live attenuated vaccines in rhesus macaques. To determine if progesterone alters the efficacy of live attenuated vaccines through local or systemic effects, seven male rhesus macaques were immunized with SHIV89.6 and then challenged intravenously with SIVmac239. Three of these animals were treated with Depo-Provera 30 days prior to the SIV challenge. The SHIV animals had significantly lower plasma viral RNA levels than the unimmunized control monkeys, but the Depo-Provera treated, SHIV-immunized animals did not. Despite the lack of protection, the Depo-Provera SHIV animals had strong SIV specific T-cell responses. However, altered patterns of NK frequency and CD38 T-cell expression prior to SIV challenge were observed in Depo-Provera SHIV animals. Depo-Provera eliminates live-attenuated lentivirus vaccine efficacy in male rhesus monkeys through systemic effects on antiviral immunity and/or viral replication.

Pegylated interferon‐α2a treatment of chronic SIV‐infected macaques

In vitro and clinical observations in HIV-infected patients receiving interferon alpha therapy have shown a reduction in HIV loads. Limited investigations have explored the innate or adaptive immune responses of IFN-alpha on SIV replication in vivo. Seven chronically infected rhesus macaques were given pegylated IFN-alpha 2a (n = four) or saline (n = three) injections once weekly for 14 weeks. Weekly peripheral blood samples were taken for safety parameters, viral load determinations, and measurements of innate and adaptive immune responses. Pharmacokinetic measurements demonstrated therapeutic peg-IFN-alpha levels for the initial period of therapy and IFN-alpha inducible antiviral molecules were increased sporadically in the PBMC mRNA of the treatment group. Despite the demonstrable effect of the IFN-alpha injections, the treatment had no effect on plasma viral RNA levels. This work demonstrates that while short term IFN-alpha therapy induces innate antiviral immunity, it does not dramatically enhance or suppress viral replication. However, studies in the SIV model to determine therapeutic potential of chronic IFN-alpha therapy for the treatment of HIV will require macaque specific cytokines.