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Antiretroviral pre-exposure prophylaxis prevents vaginal transmission of HIV-1 in humanized BLT mice.

Denton PW, Estes JD, Sun Z, Othieno FA, Wei BL, Wege AK, Powell DA, Payne D, Haase AT, Garcia JV - PLoS Med. (2008)

Bottom Line: Despite the urgency to develop and implement novel approaches capable of preventing HIV transmission, this process has been hindered by the lack of adequate small animal models for preclinical efficacy and safety testing.Effects of HIV-1 infection include CD4+ T cell depletion in gut-associated lymphoid tissue (GALT) that closely mimics what is observed in HIV-1-infected humans.We also show that pre-exposure prophylaxis with antiretroviral drugs is a highly effective method for preventing vaginal HIV-1 transmission.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, Division of Infectious Diseases, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America.

ABSTRACT

Background: Worldwide, vaginal transmission now accounts for more than half of newly acquired HIV-1 infections. Despite the urgency to develop and implement novel approaches capable of preventing HIV transmission, this process has been hindered by the lack of adequate small animal models for preclinical efficacy and safety testing. Given the importance of this route of transmission, we investigated the susceptibility of humanized mice to intravaginal HIV-1 infection.

Methods and findings: We show that the female reproductive tract of humanized bone marrow-liver-thymus (BLT) mice is reconstituted with human CD4+ T and other relevant human cells, rendering these humanized mice susceptible to intravaginal infection by HIV-1. Effects of HIV-1 infection include CD4+ T cell depletion in gut-associated lymphoid tissue (GALT) that closely mimics what is observed in HIV-1-infected humans. We also show that pre-exposure prophylaxis with antiretroviral drugs is a highly effective method for preventing vaginal HIV-1 transmission. Whereas 88% (7/8) of BLT mice inoculated vaginally with HIV-1 became infected, none of the animals (0/5) given pre-exposure prophylaxis of emtricitabine (FTC)/tenofovir disoproxil fumarate (TDF) showed evidence of infection (Chi square = 7.5, df = 1, p = 0.006).

Conclusions: The fact that humanized BLT mice are susceptible to intravaginal infection makes this system an excellent candidate for preclinical evaluation of both microbicides and pre-exposure prophylactic regimens. The utility of humanized mice to study intravaginal HIV-1 transmission is particularly highlighted by the demonstration that pre-exposure prophylaxis can prevent intravaginal HIV-1 transmission in the BLT mouse model.

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Pre-exposure Prophylaxis Prevents Intravaginal HIV-1 Transmission in Humanized BLT Mice(A) Kaplan-Meier plot of the time course to plasma antigenemia conversion following intravaginal HIV-1 exposure in BLT mice with or without the 7-d pre-exposure regimen of FTC/TDF (administered once daily starting 48 h prior to intravaginal inoculation).(B) Plasma from the seven infected BLT mice and the five FTC/TDF + HIV-1 mice was tested for the presence of HIV-1 RNA. Data presented depict the initial positive viral RNA value for each mouse examined. The dashed line indicates the limit of detection for this assay.(C–E) Shown are the levels of human CD4+ (orange squares) and CD8+ (blue circles) T cells in peripheral blood as well as the levels of HIV p24 antigenemia (black triangles) in plasma for (C) naive control (n = 6), (D) HIV-1 infected (n = 7), and (E) pre-exposure FTC/TDF-treated animals (n = 5). In (D), note that in seven of eight tested BLT mice, a single exposure to HIV-1 led to intravaginal transmission and an initial drop, with subsequent stabilization, in the levels of peripheral blood CD4+ human T cells. In contrast, no changes were observed in either the naive control (C) or BLT mice that received FTC/TDF for pre-exposure prophylaxis (E). In (D) and (E), day 0 is the day of inoculation and is indicated by an arrow. Gating strategy for flow cytometric analysis: live cells → human CD45 → human CD3 → human CD4 or CD8.(F) Immunohistochemical staining for human CD4+ cells within the vagina of a representative FTC/TDF-treated mouse demonstrating the continued presence of CD4+ T cells in this tissue (left, bar indicates 50 μm; right, bar indicates 12.5 μm; box indicates region magnified in subsequent image).
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pmed-0050016-g002: Pre-exposure Prophylaxis Prevents Intravaginal HIV-1 Transmission in Humanized BLT Mice(A) Kaplan-Meier plot of the time course to plasma antigenemia conversion following intravaginal HIV-1 exposure in BLT mice with or without the 7-d pre-exposure regimen of FTC/TDF (administered once daily starting 48 h prior to intravaginal inoculation).(B) Plasma from the seven infected BLT mice and the five FTC/TDF + HIV-1 mice was tested for the presence of HIV-1 RNA. Data presented depict the initial positive viral RNA value for each mouse examined. The dashed line indicates the limit of detection for this assay.(C–E) Shown are the levels of human CD4+ (orange squares) and CD8+ (blue circles) T cells in peripheral blood as well as the levels of HIV p24 antigenemia (black triangles) in plasma for (C) naive control (n = 6), (D) HIV-1 infected (n = 7), and (E) pre-exposure FTC/TDF-treated animals (n = 5). In (D), note that in seven of eight tested BLT mice, a single exposure to HIV-1 led to intravaginal transmission and an initial drop, with subsequent stabilization, in the levels of peripheral blood CD4+ human T cells. In contrast, no changes were observed in either the naive control (C) or BLT mice that received FTC/TDF for pre-exposure prophylaxis (E). In (D) and (E), day 0 is the day of inoculation and is indicated by an arrow. Gating strategy for flow cytometric analysis: live cells → human CD45 → human CD3 → human CD4 or CD8.(F) Immunohistochemical staining for human CD4+ cells within the vagina of a representative FTC/TDF-treated mouse demonstrating the continued presence of CD4+ T cells in this tissue (left, bar indicates 50 μm; right, bar indicates 12.5 μm; box indicates region magnified in subsequent image).

Mentions: We then tested the susceptibility of humanized BLT mice to transmission of HIV-1 administered intravaginally. Prior to HIV-1 exposure, we analyzed the peripheral blood of all humanized BLT mice to be used in our study (8 to 12 wk post-transplant) and determined that, on average, slightly more than half (51.9% ± 7.2%) of all circulating peripheral blood cells were of human origin. We inoculated BLT mice (n = 8) with a single dose of cell-free HIV-1 (CCR5-tropic primary isolate JR-CSF [18]). BLT mice that did not receive HIV-1 (n = 6) were used as naive controls. In addition, we assessed intravaginal HIV-1 transmission in BLT mice administered a 7-d course of antiretroviral drugs (n = 5). We used emtricitabine and tenofovir disoproxil fumarate (FTC/TDF) because of potency, daily dosing, and favorable profiles for both toxicity and viral resistance [31]. FTC/TDF was administered 2 d prior to intravaginal inoculation, 3 h prior to inoculation, and for 4 d postinoculation. Whereas 88% (7/8) of BLT mice inoculated with HIV-1 became infected (Figure 2A: Chi square = 7.5, df = 1, p = 0.006), none of the animals (0/5) that received FTC/TDF showed evidence of infection (Figure 2A and 2B).


Antiretroviral pre-exposure prophylaxis prevents vaginal transmission of HIV-1 in humanized BLT mice.

Denton PW, Estes JD, Sun Z, Othieno FA, Wei BL, Wege AK, Powell DA, Payne D, Haase AT, Garcia JV - PLoS Med. (2008)

Pre-exposure Prophylaxis Prevents Intravaginal HIV-1 Transmission in Humanized BLT Mice(A) Kaplan-Meier plot of the time course to plasma antigenemia conversion following intravaginal HIV-1 exposure in BLT mice with or without the 7-d pre-exposure regimen of FTC/TDF (administered once daily starting 48 h prior to intravaginal inoculation).(B) Plasma from the seven infected BLT mice and the five FTC/TDF + HIV-1 mice was tested for the presence of HIV-1 RNA. Data presented depict the initial positive viral RNA value for each mouse examined. The dashed line indicates the limit of detection for this assay.(C–E) Shown are the levels of human CD4+ (orange squares) and CD8+ (blue circles) T cells in peripheral blood as well as the levels of HIV p24 antigenemia (black triangles) in plasma for (C) naive control (n = 6), (D) HIV-1 infected (n = 7), and (E) pre-exposure FTC/TDF-treated animals (n = 5). In (D), note that in seven of eight tested BLT mice, a single exposure to HIV-1 led to intravaginal transmission and an initial drop, with subsequent stabilization, in the levels of peripheral blood CD4+ human T cells. In contrast, no changes were observed in either the naive control (C) or BLT mice that received FTC/TDF for pre-exposure prophylaxis (E). In (D) and (E), day 0 is the day of inoculation and is indicated by an arrow. Gating strategy for flow cytometric analysis: live cells → human CD45 → human CD3 → human CD4 or CD8.(F) Immunohistochemical staining for human CD4+ cells within the vagina of a representative FTC/TDF-treated mouse demonstrating the continued presence of CD4+ T cells in this tissue (left, bar indicates 50 μm; right, bar indicates 12.5 μm; box indicates region magnified in subsequent image).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2194746&req=5

pmed-0050016-g002: Pre-exposure Prophylaxis Prevents Intravaginal HIV-1 Transmission in Humanized BLT Mice(A) Kaplan-Meier plot of the time course to plasma antigenemia conversion following intravaginal HIV-1 exposure in BLT mice with or without the 7-d pre-exposure regimen of FTC/TDF (administered once daily starting 48 h prior to intravaginal inoculation).(B) Plasma from the seven infected BLT mice and the five FTC/TDF + HIV-1 mice was tested for the presence of HIV-1 RNA. Data presented depict the initial positive viral RNA value for each mouse examined. The dashed line indicates the limit of detection for this assay.(C–E) Shown are the levels of human CD4+ (orange squares) and CD8+ (blue circles) T cells in peripheral blood as well as the levels of HIV p24 antigenemia (black triangles) in plasma for (C) naive control (n = 6), (D) HIV-1 infected (n = 7), and (E) pre-exposure FTC/TDF-treated animals (n = 5). In (D), note that in seven of eight tested BLT mice, a single exposure to HIV-1 led to intravaginal transmission and an initial drop, with subsequent stabilization, in the levels of peripheral blood CD4+ human T cells. In contrast, no changes were observed in either the naive control (C) or BLT mice that received FTC/TDF for pre-exposure prophylaxis (E). In (D) and (E), day 0 is the day of inoculation and is indicated by an arrow. Gating strategy for flow cytometric analysis: live cells → human CD45 → human CD3 → human CD4 or CD8.(F) Immunohistochemical staining for human CD4+ cells within the vagina of a representative FTC/TDF-treated mouse demonstrating the continued presence of CD4+ T cells in this tissue (left, bar indicates 50 μm; right, bar indicates 12.5 μm; box indicates region magnified in subsequent image).
Mentions: We then tested the susceptibility of humanized BLT mice to transmission of HIV-1 administered intravaginally. Prior to HIV-1 exposure, we analyzed the peripheral blood of all humanized BLT mice to be used in our study (8 to 12 wk post-transplant) and determined that, on average, slightly more than half (51.9% ± 7.2%) of all circulating peripheral blood cells were of human origin. We inoculated BLT mice (n = 8) with a single dose of cell-free HIV-1 (CCR5-tropic primary isolate JR-CSF [18]). BLT mice that did not receive HIV-1 (n = 6) were used as naive controls. In addition, we assessed intravaginal HIV-1 transmission in BLT mice administered a 7-d course of antiretroviral drugs (n = 5). We used emtricitabine and tenofovir disoproxil fumarate (FTC/TDF) because of potency, daily dosing, and favorable profiles for both toxicity and viral resistance [31]. FTC/TDF was administered 2 d prior to intravaginal inoculation, 3 h prior to inoculation, and for 4 d postinoculation. Whereas 88% (7/8) of BLT mice inoculated with HIV-1 became infected (Figure 2A: Chi square = 7.5, df = 1, p = 0.006), none of the animals (0/5) that received FTC/TDF showed evidence of infection (Figure 2A and 2B).

Bottom Line: Despite the urgency to develop and implement novel approaches capable of preventing HIV transmission, this process has been hindered by the lack of adequate small animal models for preclinical efficacy and safety testing.Effects of HIV-1 infection include CD4+ T cell depletion in gut-associated lymphoid tissue (GALT) that closely mimics what is observed in HIV-1-infected humans.We also show that pre-exposure prophylaxis with antiretroviral drugs is a highly effective method for preventing vaginal HIV-1 transmission.

View Article: PubMed Central - PubMed

Affiliation: Department of Internal Medicine, Division of Infectious Diseases, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America.

ABSTRACT

Background: Worldwide, vaginal transmission now accounts for more than half of newly acquired HIV-1 infections. Despite the urgency to develop and implement novel approaches capable of preventing HIV transmission, this process has been hindered by the lack of adequate small animal models for preclinical efficacy and safety testing. Given the importance of this route of transmission, we investigated the susceptibility of humanized mice to intravaginal HIV-1 infection.

Methods and findings: We show that the female reproductive tract of humanized bone marrow-liver-thymus (BLT) mice is reconstituted with human CD4+ T and other relevant human cells, rendering these humanized mice susceptible to intravaginal infection by HIV-1. Effects of HIV-1 infection include CD4+ T cell depletion in gut-associated lymphoid tissue (GALT) that closely mimics what is observed in HIV-1-infected humans. We also show that pre-exposure prophylaxis with antiretroviral drugs is a highly effective method for preventing vaginal HIV-1 transmission. Whereas 88% (7/8) of BLT mice inoculated vaginally with HIV-1 became infected, none of the animals (0/5) given pre-exposure prophylaxis of emtricitabine (FTC)/tenofovir disoproxil fumarate (TDF) showed evidence of infection (Chi square = 7.5, df = 1, p = 0.006).

Conclusions: The fact that humanized BLT mice are susceptible to intravaginal infection makes this system an excellent candidate for preclinical evaluation of both microbicides and pre-exposure prophylactic regimens. The utility of humanized mice to study intravaginal HIV-1 transmission is particularly highlighted by the demonstration that pre-exposure prophylaxis can prevent intravaginal HIV-1 transmission in the BLT mouse model.

Show MeSH
Related in: MedlinePlus