Tracking of dye‐labeled lymphocytes in rhesus macaques

Ms, Salvato; Rater, M; Cd, Pauza

doi:10.1111/j.1600-0684.1996.tb00202.x

Cited by 8 publications

(5 citation statements)

References 30 publications

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“…Plasma TFV was detected at higher levels in macaques than in women who applied vaginal TFV gel containing 40 mg (16,27). This difference may be explained by the approximately 12-fold-smaller blood volume in macaques, which may concentrate TFV, thus making it more easily detected in macaques than in women, especially if vaginal absorption is similar in both species (26). We also found no reduction in the acute viremia in breakthrough infections compared to controls, reflecting insignificant antiviral activity from any systemic TFV exposure by the once-weekly gel dosing modality.…”

Section: Discussionmentioning

confidence: 78%

Durable Protection from Vaginal Simian-Human Immunodeficiency Virus Infection in Macaques by Tenofovir Gel and Its Relationship to Drug Levels in Tissue

Dobard

Sharma

Martin

et al. 2012

J Virol

100

117

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A vaginal gel containing 1% tenofovir (TFV) was found to be safe and effective in reducing HIV infection in women when used pericoitally. Because of the long intracellular half-life of TFV and high drug exposure in vaginal tissues, we hypothesized that a vaginal gel containing TFV may provide long-lasting protection. Here, we performed delayed-challenge experiments and showed that vaginal 1% TFV gel protected 4/6 macaques against vaginal simian-human immunodeficiency virus (SHIV) exposures occurring 3 days after gel application, demonstrating long-lasting protection. Despite continued gel dosing postinfection, neither breakthrough infection had evidence of drug resistance by ultrasensitive testing of SHIV in plasma and vaginal lavage. Analysis of the active intracellular tenofovir diphosphate (TFV-DP) in vaginal lymphocytes collected 4 h to 3 days after gel dosing persistently showed high TFV-DP levels (median, 1,810 fmol/10 6 cells) between 4 and 24 h that exceed the 95% inhibitory concentration (IC 95 ), reflecting rapid accumulation and long persistence. In contrast to those in peripheral blood mononuclear cells (PBMCs) following oral dosing, TFV-DP levels in vaginal lymphocytes decreased approximately 7-fold by 3 days, exhibiting a much higher rate of decay. We observed a strong correlation between intracellular TFV-DP in vaginal lymphocytes, in vitro antiviral activity, and in vivo protection, suggesting that TFV-DP above the in vitro IC 95 in vaginal lymphocytes is a good predictor of high efficacy. Data from this model reveal an extended window of protection by TFV gel that supports coitus-independent use. The identification of protective TFV-DP concentrations in vaginal lymphocytes may facilitate the evaluation of improved delivery methods of topical TFV and inform clinical studies. Human immunodeficiency virus (HIV) continues to spread primarily through heterosexual routes, with women being disproportionately infected in many parts of the world (30, 35). While condoms have been shown to be one of the most reliable methods for preventing HIV transmission, such interventions are often limited by adherence and the ability of women to negotiate their use (24, 37). In the absence of an effective HIV vaccine, increasing efforts have been made toward developing vaginal gels formulated with antiretroviral (ARV) drugs, as a femalecontrolled option for women to protect themselves against HIV acquisition (10,21,33,37).Topical gels containing tenofovir (TFV), a nucleotide analogue reverse transcriptase inhibitor, have recently shown great promise against vaginal HIV transmission. Results of the CAPRISA 004 trial demonstrated for the first time that women who used a vaginal gel containing 1% TFV were 39% less likely overall to contract HIV than those who used a placebo gel (1). The trial evaluated a coitus-dependent before-and-after (BAT) modality, with one gel application administered up to 12 h before sex followed by a second gel application up to 12 h after sex. Importantly, effectiveness was found to be dependen...

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Section: Discussionmentioning

confidence: 78%

Durable Protection from Vaginal Simian-Human Immunodeficiency Virus Infection in Macaques by Tenofovir Gel and Its Relationship to Drug Levels in Tissue

Dobard

Sharma

Martin

et al. 2012

J Virol

100

117

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“…Thus, the volume in which SIV particles are distributed could be directly determined for each monkey. As summarized in Table 1, the total volumes of distribution were 250 to 875 ml, or only about 1.3to 2.1-fold larger than the calculated plasma volume (21). This demonstrates that the in vivo volume of distribution of exogenously infused viral particles is substantially smaller (0.2 to 0.3) than the total extracellular fluid volume.…”

mentioning

confidence: 82%

“…a Animal 531 was the only male used in the experiments. Blood volume is calculated as 53 ml/kg for males and 44 ml/kg for female (21). Plasma volume is about 60% of blood volume.…”

mentioning

confidence: 99%

Rapid Clearance of Simian Immunodeficiency Virus Particles from Plasma of Rhesus Macaques

Zhang

Dailey²,

Tian

et al. 1999

J Virol

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Perturbation of the equilibrium between human immunodeficiency virus type 1 (HIV-1) and the infected host by administering antiretroviral agents has revealed the rapid turnover of both viral particles and productively infected cells. In this study, we used the infusion of simian immunodeficiency virus (SIV) particles into rhesus macaques to obtain a more accurate estimate of viral clearance in vivo. Consistently, exogenously infused virions were cleared from plasma with an extremely short half-life, on the order of minutes (a mean of 3.3 min). This new estimate is ∼100-fold lower than the upper bound of 6 h previously reported for HIV-1 in infected humans. In select animals, multiple tissues were collected at the completion of each experiment to track the potential sites of virion clearance. Detectable levels of SIV RNA were found in lymph nodes, spleen, lungs, and liver, but not in other tissues examined. However, only ∼1 to 10% or less of the infused virions were accounted for by the thorough tissue sampling, indicating that the vast majority of the infused particles must have been degraded over a short period of time. Should the rapid clearance of virions described here be applicable to infected patients, then HIV-1 production and thus the number of productively infected CD4+ T lymphocytes or the viral burst size must be proportionally higher than previous minimal estimates.

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“…To obtain the AUC, or the total virion production, the viral load data, expressed as SIV RNA copies per ml, was integrated until day 72 postinoculation and then multiplied by a conversion factor of 53 ml of blood per kg of body weight (29). This process yielded a minimal estimate because virions that resided in extravascular spaces and virions that were produced after day 72 were not considered.…”

Section: [8]mentioning

confidence: 99%

Determination of virus burst size in vivo using a single-cycle SIV in rhesus macaques

Chen

Mascio

Perelson

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

144

117

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A single-cycle simian immunodeficiency virus (scSIV) that undergoes only one round of infection and replication was constructed to calculate the total number of virons produced by an SIV-infected cell in vivo. Four Mamu-A*01 rhesus macaques were inoculated on two occasions 11 weeks apart with the scSIV by ex vivo infection and i.v. reinfusion of autologous cells. After each inoculation, plasma viral loads peaked between 1 and 2.5 days and then declined exponentially in one or two phases to below detection limits within 2 weeks. Although higher levels of SIV-specific cytotoxic T lymphocytes and modest increases in antibody responses were observed for each animal after the second inoculation, decay rates of the infected cells were only minimally affected. Analyzing the viral load data with a mathematical model, the in vivo viral burst size averaged 4.0 ؋ 10 4 and 5.5 ؋ 10 4 virions per cell for the first and second inoculations, respectively, with no significant difference between the two inoculations. This estimate, in conjunction with our prior understanding of other quantitative viral and cellular parameters during SIV and HIV infection, provides critical insights into the dynamic process of viral production and its interplay with the infected host in vivo.dynamic ͉ HIV ͉ highly active antiretroviral therapy ͉ half-life ͉ modeling T he measurement of HIV and simian immunodeficiency virus (SIV) dynamic parameters through mathematical modeling has provided important insights into the virus-host relationship. One key viral dynamic parameter that remains ambiguous is the in vivo viral burst size, i.e., the total number of virions produced by an infected cell during its lifetime. Current HIV burst size estimates rely on either viral inhibitors, washouts of infected cells, or serial dilutions of infected cells to control for multiple rounds of infection (1)(2)(3). Alternatively, quantitative image analyses with in situ hybridization and quantitative, competitive RT-PCR of bulk tissue or single cells at limiting dilution (4-6) provide only transient ''snapshots'' of the infected cells, which may greatly underestimate this value.To better determine the viral burst size in vivo, we used a single-cycle SIV (scSIV) that undergoes only one round of infection and replication (Fig. 1). This strategy enabled the determination of specific viral dynamic parameters in vivo without the confounding effects of subsequent viral spread and production. Our previous studies have shown that exogenously infused SIV particles into rhesus macaques and free HIV-1 virions in HIV-1-infected individuals are cleared rapidly from the plasma (7,8). Such rapid clearance posed a challenge in the use of nonreplicating viral particles for in vivo dynamic studies in that these directly inoculated particles may be cleared before sufficient numbers of cells are infected. In addition, calculating the burst size from such experiments required an estimate of the rate of infection. Therefore, an infection strategy of first coculturing the scSIV particles ex...

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Tracking of dye‐labeled lymphocytes in rhesus macaques

Cited by 8 publications

References 30 publications

Durable Protection from Vaginal Simian-Human Immunodeficiency Virus Infection in Macaques by Tenofovir Gel and Its Relationship to Drug Levels in Tissue

Durable Protection from Vaginal Simian-Human Immunodeficiency Virus Infection in Macaques by Tenofovir Gel and Its Relationship to Drug Levels in Tissue

Rapid Clearance of Simian Immunodeficiency Virus Particles from Plasma of Rhesus Macaques

Determination of virus burst size in vivo using a single-cycle SIV in rhesus macaques

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