Shambavi Subbarao

Chemoprophylaxis with Tenofovir Disoproxil Fumarate Provided Partial Protection against Infection with Simian Human Immunodeficiency Virus in Macaques Given Multiple Virus Challenges

We examined the efficacy of tenofovir disoproxil fumarate (TDF) in blocking simian human immunodeficiency virus (SHIV) infection in Chinese rhesus macaques. Once weekly for 14 weeks or until a macaque became infected, 12 male macaques were inoculated intrarectally with amounts of SHIV(SF162P3) (10 median tissue culture infective doses; 3.8 x 10(5) virus particles) that were approximately 5-fold higher than the human immunodeficiency virus type 1 RNA levels noted in human semen during an acute infection. Of the 12 macaques, 4 received oral TDF daily, 4 received oral TDF once weekly, and 4 (control animals) received no TDF. The control animals became infected after receiving a median of 1.5 virus inoculations; macaques receiving TDF daily (1 macaque remained uninfected after 14 inoculations) and those receiving TDF weekly became infected after a median duration of 6.0 and 7.0 weeks, respectively. Although infection was delayed in treated macaques, compared with control macaques, the differences were not statistically significant (P=.315); however, the study was limited by the small numbers of animals evaluated and the variability in blood levels of TDF that resulted from oral dosing. These data demonstrate that treatment with oral TDF provided partial protection against SHIV infection but ultimately did not protect all TDF treated animals against multiple virus challenges.

Intersubtype Human Immunodeficiency Virus Type 1 Superinfection following Seroconversion to Primary Infection in Two Injection Drug Users

ABSTRACT In this study, we describe two cases of human immunodeficiency virus type 1 (HIV-1) intersubtype superinfection with CRF01_AE and subtype B strains, which occurred in two injection drug users participating in a prospective cohort study in Bangkok, Thailand. In both cases, the superinfecting strain was detected by molecular and serologic analyses several weeks after complete seroconversion to the primary infection with a strain belonging to a different subtype. Superinfection occurred despite specific T-cell and humoral antibody responses to the primary virus. In both cases, cross-subtype immune responses were limited or absent prior to the second infection. These data show that, in some individuals, the quality and quantity of the immune response elicited by primary HIV-1 infection may not protect against superinfection. This finding has important implications for vaccine design. HIV-1 vaccines, at a minimum, will need to include potent, broadly protective, conserved immunogens derived from several group M subtypes.

Continued high HIV-1 incidence in a vaccine trial preparatory cohort of injection drug users in Bangkok, Thailand

Background A large epidemic of HIV-1 subtype B began among injection drug users (IDUs) in Bangkok in 1988. Despite ongoing prevention efforts, HIV-1 prevalence among IDUs remained at 30–50% through the 1990s. ObjectivesTo measure the incidence of HIV-1 infection and related risk factors to guide prevention efforts and to evaluate the feasibility of conducting an HIV vaccine efficacy trial. Design and methodsA prospective cohort study in which IDUs attending methadone treatment programs in Bangkok were screened during 1995–1996 for enrollment into the study. IDUs found to be HIV-seronegative on two occasions were offered enrollment with follow-up visits every 4 months. On each visit participants were evaluated with a questionnaire and serologic testing. ResultsA total of 1209 HIV-negative IDUs were enrolled. Through the end of 1998, the overall HIV-1 incidence rate was 5.8 (95% confidence interval, 4.8–6.8) per 100 person–years of follow-up. HIV-1 subtypes E and B accounted for 79 and 21% of infections, respectively. On multivariate analysis, HIV-1 seroconversion was primarily associated with the frequency of heroin injection, the sharing of injection equipment, and incarceration, especially with drug injection. Sexual behavior was not associated with increased risk for HIV-1. Risk factors for infection with HIV-1 subtypes E and B were similar. ConclusionHIV-1 transmission risk remains high among Bangkok IDUs despite methadone treatment and other current prevention strategies. There is an urgent need to address this ongoing epidemic, especially in jails and prisons. This study led to the initiation in 1999 of a phase III HIV-1 vaccine efficacy trial in this population.

In Vitro Comparison of Topical Microbicides for Prevention of Human Immunodeficiency Virus Type 1 Transmission

ABSTRACT A standardized protocol was used to compare cellular toxicities and anti-human immunodeficiency virus type 1 (HIV-1) activities of candidate microbicides formulated for human use. The microbicides evaluated were cellulose acetate phthalate (CAP), Carraguard, K-Y plus nonoxynol-9 (KY-N9), PRO 2000 (0.5 and 4%), SPL7013 (5%), UC781 (0.1 and 1%), and Vena Gel, along with their accompanying placebos. Products were evaluated for toxicity on cervical and colorectal epithelial cell lines, peripheral blood mononuclear cells (PBMCs), and macrophages (MΦ) by using an ATP release assay, and they were tested for their effect on transepithelial resistance (TER) of polarized epithelial monolayers. Anti-HIV-1 activity was evaluated in assays for transfer of infectious HIV-1 from epithelial cells to activated PBMCs and for PBMC and MΦ infection. CAP, Carraguard, PRO 2000, SPL7013, and UC781 along with their placebos were 20- to 50-fold less toxic than KY-N9 and Vena Gel. None of the nontoxic product concentrations disrupted the TER. Transfer of HIV-1Ba-L from epithelial cells to PBMCs and PBMC and MΦ infection with laboratory-adapted HIV-1Ba-L and HIV-1LAI isolates were inhibited by all products except Carraguard, KY-N9, and Vena Gel. KY-N9, Vena Gel, and Carraguard were not effective in blocking PBMC infection with primary HIV-1A, HIV-1C, and HIV-1CRF01-AE isolates. The concordance of these toxicity results with those previously reported indicates that our protocol may be useful for predicting toxicity in vivo. Moreover, our systematic anti-HIV-1 testing provides a rational basis for making better informed decisions about which products to consider for clinical trials.

Maternal Virus Load and Perinatal Human Immunodeficiency Virus Type 1 Subtype E Transmission, Thailand

To determine the rate and risk factors for human immunodeficiency virus (HIV)-1 subtype E perinatal transmission, with focus on virus load, pregnant HIV-infected women and their formula-fed infants were followed prospectively in Bangkok. Of 281 infants with known outcome, 68 were infected (transmission rate, 24.2%; 95% confidence interval, 19.3%-29.6%). Transmitting mothers had a 4.3-fold higher median plasma HIV RNA level at delivery than did nontransmitters (P<.001). No transmission occurred at <2000 copies/mL. On multivariate analysis, prematurity (adjusted odds ratio [AOR], 4.5), vaginal delivery (AOR, 2.9), low NK cell percentage (AOR, 2.4), and maternal virus load were associated with transmission. As RNA quintiles increased, the AOR for transmission increased linearly from 4.5 to 24.8. Two-thirds of transmission was attributed to virus load>10,000 copies/mL. Although risk is multifactorial, high maternal virus load at delivery strongly predicts transmission. This may have important implications for interventions designed to reduce perinatal transmission.

Viral load differences in early infection with two HIV-1 subtypes.

ObjectivesInformation on early HIV-1 infection has come primarily from studies of persons infected with subtype B in North America and Europe; much less is known about other subtypes. The purpose of the present study was to compare the virologic and immunologic parameters following seroconversion among recently-infected persons infected with either of two different HIV-1 subtypes. MethodA prospective cohort study was carried out at methadone treatment clinics administered by the Bangkok Metropolitan Administration, Thailand. A total of 130 HIV-1-infected seroconverters (103 with HIV-1 subtype E and 27 with subtype B) were included in the study. The main outcome measures were serial HIV-1 RNA viral load, natural killer cell percentage, CD4 and CD8 lymphocyte counts since seroconversion. ResultsThe demographic and behavioral characteristics of persons with either subtype were similar. Median RNA viral levels at the earliest time within 3 months of seroconversion were more than three times higher for persons infected with subtype E than subtype B (63 100 versus 18 050 copies/ml, P = 0.001). However, this difference decreased over time such that viral loads were similar at 12, 18, and 24 months following seroconversion. The CD4 and CD8 lymphocyte counts were similar in infections with either subtype during the entire period up to 24 months post-seroconversion. ConclusionsHigher viral loads associated with subtype E may result from inter-subtype biological differences; however, the epidemiological dynamics of transmission in Bangkok may have also contributed to this phenomenon.

Correlation between Human Immunodeficiency Virus Type 1 RNA Levels in the Female Genital Tract and Immune Activation Associated with Ulceration of the Cervix

To address the hypothesis that local immune activation resulting from genital ulceration enhances human immunodeficiency virus type 1 (HIV-1) replication and shedding into the genital tract, paired plasma and cervicovaginal lavage (CVL) samples were obtained from 12 HIV-infected women before and after treatment of cervical intraepithelial lesions. Two weeks after treatment, inflammation and ulceration of the cervix were accompanied by major increases in mean concentrations of HIV-1 RNA (200-fold), tumor necrosis factor-alpha, interleukin 6, and soluble markers shed by activated lymphocytes and macrophages (sCD25 and sCD14, respectively) in CVL samples (P<.01 for each), but not plasma. Strong temporal and quantitative correlations were observed between concentrations of immunological markers and HIV-1 load in this compartment during a 10-week follow-up. Furthermore, in the presence of genital ulceration, HIV-1 in CVL samples was more readily captured by antibodies directed against virion-associated HLA-DR, a marker of host-cell activation, compared with virus in plasma. We suggest that local immune activation increases HIV-1 load in genital secretions, potentially increasing the risk of HIV-1 transmission.

HIV Type 1 Subtypes in Guangxi Province, China, 1996

81 HIV-1 INFECTION WAS FIRST DOCUMENTED IN China in 1985; by 1997, the Joint United Nations Programme on HIV/AIDS (UNAIDS) estimated that there were 200,000 to 400,000 HIV-infected persons living in China among a population of 1.2 billion.3 To date, most infections have occurred among injection drug users (IDUs), primarily in ethnic minority communities in Yunnan, a southwestern province bordering Myanmar (Burma), Laos, and Vietnam. This province can be seen as an extension of the a Golden Triangleo region of northern Thailand, Myanmar, and Laos, one of the world’ s foremost opiumand heroin-producing areas. In recent years, HIV-1 transmission has extended to new areas of China, and sexual transmission has increased in importance. The HIV-1 epidemic among IDUs in Yunnan province was primarily due to env subtype B strains, both typical North American/European-like subtype B strains and strains that clustered on phylogenetic analyses with subtype B strains found among IDUs in Thailand, termed B 9 (formerly Thai B).9±11 Subsequently, subtype C viruses were identified among IDUs in Yunnan. More recently, both subtype C and subtype E strains have been reported among geographically separate groups of IDUs in Guangxi province.13 There also appear to have been multiple other introductions of subtype E strains in China10,14 and subtype A has also been identified.10 We investigated the molecular epidemiology of HIV-1 in Guangxi, a southwestern Chinese province bordering Yunnan, Guizhou, Hunan, and Guangdong provinces and northern Vietnam. Guangxi, a mountainous, subtropical area, has a population of approximately 45 million, of whom about a third are ethnic minorities. From April through July 1996, blood samples were collected from HIV-seropositive persons identified at blood donation centers, drug treatment centers, and other testing locations. Specimens were obtained from 44 persons: 25 commercial blood donors (mean age, 24.5 years [range, 18±36]; 21 male and 4 female), 16 IDUs from drug treatment centers (mean age, 22.8 years [range, 16±38]; 14 male and 2 female), 2 men (aged 29 and 35 years) who had traveled to Thailand and reported sex with female sex workers, and 1 female (aged 36) who did not inject drugs and whose husband had AIDS. Fifteen of the 16 IDUs were identified in Pingxiang, a city near the border with Vietnam; the other IDU was located in Nanning, in central Guangxi. The other 28 persons were identified from throughout the province. All specimens were HIV-1 positive by enzyme immunoassay (EIA) and Western blot when tested at the Guangxi AIDS Surveillance and Testing Center, Nanning. Unlinked serum specimens were transferred to Nonthaburi, Thailand, and then to Atlanta, Georgia for further characterization. In Thailand, specimens were tested with 14-amino acid V3loop peptide enzyme immunoassays (PEIAs) highly specific for subtypes B 9 and E from Thailand.15±17 Serum specimens were later sent to the Centers for Disease Control and Prevention (Atlanta, GA) for genetic characterization. RNA was prepared with a blood kit from Qiagen (Chatsworth, CA). RNA from each sample was reverse transcribed (primer JH35R) and subsequently amplified by nested PCR (outer primers JH44F/JH35R and inner primers JH33F/JH48R). The 525-bp nested C2±V4 PCR product encompasses the V3 loop. The sequences of these HIV-1 group M env (gp120) gene-based degenerate/inosine primers with coordinates on HIV-MNCG sequence (in parentheses) are as follows:

New HIV type 1 CRF01_AE/B recombinants displaying unique distribution of breakpoints from incident infections among injecting drug users in Thailand

The goals of this study were to identify and characterize recombinant human immunodeficiency virus type 1 (HIV-1) genomes among incident infections in a prospective cohort study of injecting drug users (IDUs) in Bangkok, Thailand. Through cross-sectional, comparative phylogenetic analysis of the protease and env (C2-V4) gene regions, subtype discordance was observed in HIV-1 sequences from 4 of 111 IDUs (3.5%). Near-full-length HIV-1 genome sequences of the four strains revealed that in all four, the gp120 sequences clustered with a CRF01_AE prototype, while the remainder of the genomes displayed distinct mosaic patterns, with multiple breakpoints between HIV-1 CRF01_AE and subtype B-like regions. Two of the four HIV-1 recombinant strains displayed a nearly identical mosaic structure, suggesting the possible emergence and spread of a potentially new circulating recombinant form of HIV-1. Further characterization of these and other recombinant genomes through long-term follow-up will be important in understanding the generation of viral diversity and escape from the hosts immune responses. This information will be especially important for vaccine development.

Systemic and mucosal immunological responses during repeated mucosal SHIV162P3 challenges prior to and following infection in pigtailed macaques

Local and systemic immunological changes following vaginal HIV-1 exposures are poorly characterized and may influence susceptibility to infection. Therefore, we examined longitudinal mucosal, plasma cytokine profiles and viral-specific T-cell responses (vSTRs) before and during weekly repeated low-dose SHIV(SF162P3) viral challenges in six female pigtailed macaques, even in the absence of overt systemic infection. Following a single viral challenge, induction of several cytokines was detected consistently in cervico-vaginal lavages (CVL). With additional exposure and documented systemic infection, a hallmark of response profile was defined as peak levels in both CVL (MCP-1, MIP-1alpha, TNF-alpha, IL-1beta, IL-1RA and IL-8) and plasma cytokines (MCP-1, eotaxin and IL-1RA) in the macaques. In the periphery, vSTRs were observed within the first one or two viral challenges, but prior to the detection of systemic infection in 5/6 exposed pigtailed macaques. These findings provide valuable information regarding mucosal HIV-1 infection that may benefit microbicide research and development.