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Semen-mediated enhancement of HIV infection is donor-dependent and correlates with the levels of SEVI.

Kim KA, Yolamanova M, Zirafi O, Roan NR, Staendker L, Forssmann WG, Burgener A, Dejucq-Rainsford N, Hahn BH, Shaw GM, Greene WC, Kirchhoff F, Münch J - Retrovirology (2010)

Bottom Line: Despite its importance for the global spread of HIV-1, however, the effect of semen on virus infection is controversial.We show that semen rapidly and effectively enhances the infectivity of HIV-1, HIV-2, and SIV.Our results show that semen strongly enhances the infectivity of HIV-1 and other primate lentiviruses and that SEVI contributes to this effect.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Molecular Virology, University Hospital Ulm, 89081 Ulm, Germany.

ABSTRACT

Background: HIV-1 is usually transmitted in the presence of semen. We have shown that semen boosts HIV-1 infection and contains fragments of prostatic acid phosphatase (PAP) forming amyloid aggregates termed SEVI (semen-derived enhancer of viral infection) that promote virion attachment to target cells. Despite its importance for the global spread of HIV-1, however, the effect of semen on virus infection is controversial.

Results: Here, we established methods allowing the meaningful analysis of semen by minimizing its cytotoxic effects and partly recapitulating the conditions encountered during sexual HIV-1 transmission. We show that semen rapidly and effectively enhances the infectivity of HIV-1, HIV-2, and SIV. This enhancement occurs independently of the viral genotype and coreceptor tropism as well as the virus producer and target cell type. Semen-mediated enhancement of HIV-1 infection was also observed under acidic pH conditions and in the presence of vaginal fluid. We further show that the potency of semen in boosting HIV-1 infection is donor dependent and correlates with the levels of SEVI.

Conclusions: Our results show that semen strongly enhances the infectivity of HIV-1 and other primate lentiviruses and that SEVI contributes to this effect. Thus, SEVI may play an important role in the sexual transmission of HIV-1 and addition of SEVI inhibitors to microbicides may improve their efficacy.

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SE enhances founder HIV infection and boosts HIV infection independently of the viral producer and target cell type. (A) Effect of SE on HIV particles carrying gp120/41 from founder viruses. Pseudotyped HIV-1 particles were generated by transient transfection of 293T cells with an env-defective HIV-1 NL4-3 backbone and plasmids expressing the Env proteins previously described (34). Virions were treated with medium, 10 μg/ml SEVI or 10% SE and used to infect TZM-bl cells. The inoculum was removed after 2 hrs and infection rates were determined 2 dpi. Shown are the average levels of triplicate TZM-bl cell infections ± SD. (B) Correlation between the magnitudes of SEVI and SE-mediated enhancement of HIV-1 pseudotype infection shown in Fig 4A. N-fold enhanced infection rates were calculated by dividing infection rates obtained in the presence of SEVI or SE by those of mock-treated virus infection. (C) SE enhances infection of testis derived HIV-1. X4 tropic HIV-1 IIIb and R5 tropic SF162 were harvested from infected testis tissue, treated with indicated concentrations of SE and used to infect TZM-bl cells. (D, E) SE enhances the infectiousness of HIV-1 for PBMCs and macrophages. Stocks of an R5-tropic HIV-1 NL4-3 V3 variant (92TH04.12) containing the luciferase reporter gene in place of nef were generated by transient transfection of 293T cells. Virus stocks were treated with the indicated concentrations of SE and used to infect PBMC (D) and macrophages (E). Similar results were obtained using various primary HIV-1 strains. (F) SE favours in trans-infection of T cells by viral particles bound to epithelial cells. CaSki cells derived from an epithelial cervical carcinoma were exposed to HIV-1 treated with SE or medium for 3 hrs. Subsequently, the virus inoculum was washed out and the cells were cocultivated with CEM-M7 cells for three days. Infection rates were determined by luciferase assay. The numbers above the bars indicate n-fold enhancement relative to the infectivity measured using PBS/medium-treated virus stocks.
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Figure 4: SE enhances founder HIV infection and boosts HIV infection independently of the viral producer and target cell type. (A) Effect of SE on HIV particles carrying gp120/41 from founder viruses. Pseudotyped HIV-1 particles were generated by transient transfection of 293T cells with an env-defective HIV-1 NL4-3 backbone and plasmids expressing the Env proteins previously described (34). Virions were treated with medium, 10 μg/ml SEVI or 10% SE and used to infect TZM-bl cells. The inoculum was removed after 2 hrs and infection rates were determined 2 dpi. Shown are the average levels of triplicate TZM-bl cell infections ± SD. (B) Correlation between the magnitudes of SEVI and SE-mediated enhancement of HIV-1 pseudotype infection shown in Fig 4A. N-fold enhanced infection rates were calculated by dividing infection rates obtained in the presence of SEVI or SE by those of mock-treated virus infection. (C) SE enhances infection of testis derived HIV-1. X4 tropic HIV-1 IIIb and R5 tropic SF162 were harvested from infected testis tissue, treated with indicated concentrations of SE and used to infect TZM-bl cells. (D, E) SE enhances the infectiousness of HIV-1 for PBMCs and macrophages. Stocks of an R5-tropic HIV-1 NL4-3 V3 variant (92TH04.12) containing the luciferase reporter gene in place of nef were generated by transient transfection of 293T cells. Virus stocks were treated with the indicated concentrations of SE and used to infect PBMC (D) and macrophages (E). Similar results were obtained using various primary HIV-1 strains. (F) SE favours in trans-infection of T cells by viral particles bound to epithelial cells. CaSki cells derived from an epithelial cervical carcinoma were exposed to HIV-1 treated with SE or medium for 3 hrs. Subsequently, the virus inoculum was washed out and the cells were cocultivated with CEM-M7 cells for three days. Infection rates were determined by luciferase assay. The numbers above the bars indicate n-fold enhancement relative to the infectivity measured using PBS/medium-treated virus stocks.

Mentions: To assess the possible relevance of SE for sexual virus transmission, we next examined its effect on HIV-1 founder viruses, which are most likely the ones transmitted during sexual intercourse [34]. We found that SEVI and pooled SE enhance the infectiousness of HIV-1 particles pseudotyped with envelope glycoproteins derived from 25 different transmitted/founder viruses [34] in single round infection assays by 5- to 48 fold (Figure 4A). Notably, the magnitudes of infectivity enhancement by SEVI and SE correlated significantly (p = 0.0006) (Figure 4B). To further examine the effect of SE on viral particles generated by the relevant producer cells in vivo we harvested HIV-1 from ex vivo infected testis tissue [29,31]. We found that SE clearly increases the infectiousness of testis-derived R5- and X4-tropic HIV-1 strains (Figure 4C). Further experiments using luciferase reporter viruses showed that SE also promotes HIV-1 infection of primary T cells and macrophages, the relevant target cells of HIV-1 in vivo (Figure 4D and 4E). Finally, we examined whether SE also affects HIV-1 infection in trans. Our results showed that SE increases the transmission of R5-tropic HIV-1 from non-permissive CaSki human cervical epithelial carcinoma cells to susceptible T cells about 80-fold (Figure 4F). Typically, the strongest enhancing effects of SE were observed with low doses of freshly produced highly infectious HIV-1 virions, irrespective of the virus strain and producer or target cell type.


Semen-mediated enhancement of HIV infection is donor-dependent and correlates with the levels of SEVI.

Kim KA, Yolamanova M, Zirafi O, Roan NR, Staendker L, Forssmann WG, Burgener A, Dejucq-Rainsford N, Hahn BH, Shaw GM, Greene WC, Kirchhoff F, Münch J - Retrovirology (2010)

SE enhances founder HIV infection and boosts HIV infection independently of the viral producer and target cell type. (A) Effect of SE on HIV particles carrying gp120/41 from founder viruses. Pseudotyped HIV-1 particles were generated by transient transfection of 293T cells with an env-defective HIV-1 NL4-3 backbone and plasmids expressing the Env proteins previously described (34). Virions were treated with medium, 10 μg/ml SEVI or 10% SE and used to infect TZM-bl cells. The inoculum was removed after 2 hrs and infection rates were determined 2 dpi. Shown are the average levels of triplicate TZM-bl cell infections ± SD. (B) Correlation between the magnitudes of SEVI and SE-mediated enhancement of HIV-1 pseudotype infection shown in Fig 4A. N-fold enhanced infection rates were calculated by dividing infection rates obtained in the presence of SEVI or SE by those of mock-treated virus infection. (C) SE enhances infection of testis derived HIV-1. X4 tropic HIV-1 IIIb and R5 tropic SF162 were harvested from infected testis tissue, treated with indicated concentrations of SE and used to infect TZM-bl cells. (D, E) SE enhances the infectiousness of HIV-1 for PBMCs and macrophages. Stocks of an R5-tropic HIV-1 NL4-3 V3 variant (92TH04.12) containing the luciferase reporter gene in place of nef were generated by transient transfection of 293T cells. Virus stocks were treated with the indicated concentrations of SE and used to infect PBMC (D) and macrophages (E). Similar results were obtained using various primary HIV-1 strains. (F) SE favours in trans-infection of T cells by viral particles bound to epithelial cells. CaSki cells derived from an epithelial cervical carcinoma were exposed to HIV-1 treated with SE or medium for 3 hrs. Subsequently, the virus inoculum was washed out and the cells were cocultivated with CEM-M7 cells for three days. Infection rates were determined by luciferase assay. The numbers above the bars indicate n-fold enhancement relative to the infectivity measured using PBS/medium-treated virus stocks.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 4: SE enhances founder HIV infection and boosts HIV infection independently of the viral producer and target cell type. (A) Effect of SE on HIV particles carrying gp120/41 from founder viruses. Pseudotyped HIV-1 particles were generated by transient transfection of 293T cells with an env-defective HIV-1 NL4-3 backbone and plasmids expressing the Env proteins previously described (34). Virions were treated with medium, 10 μg/ml SEVI or 10% SE and used to infect TZM-bl cells. The inoculum was removed after 2 hrs and infection rates were determined 2 dpi. Shown are the average levels of triplicate TZM-bl cell infections ± SD. (B) Correlation between the magnitudes of SEVI and SE-mediated enhancement of HIV-1 pseudotype infection shown in Fig 4A. N-fold enhanced infection rates were calculated by dividing infection rates obtained in the presence of SEVI or SE by those of mock-treated virus infection. (C) SE enhances infection of testis derived HIV-1. X4 tropic HIV-1 IIIb and R5 tropic SF162 were harvested from infected testis tissue, treated with indicated concentrations of SE and used to infect TZM-bl cells. (D, E) SE enhances the infectiousness of HIV-1 for PBMCs and macrophages. Stocks of an R5-tropic HIV-1 NL4-3 V3 variant (92TH04.12) containing the luciferase reporter gene in place of nef were generated by transient transfection of 293T cells. Virus stocks were treated with the indicated concentrations of SE and used to infect PBMC (D) and macrophages (E). Similar results were obtained using various primary HIV-1 strains. (F) SE favours in trans-infection of T cells by viral particles bound to epithelial cells. CaSki cells derived from an epithelial cervical carcinoma were exposed to HIV-1 treated with SE or medium for 3 hrs. Subsequently, the virus inoculum was washed out and the cells were cocultivated with CEM-M7 cells for three days. Infection rates were determined by luciferase assay. The numbers above the bars indicate n-fold enhancement relative to the infectivity measured using PBS/medium-treated virus stocks.
Mentions: To assess the possible relevance of SE for sexual virus transmission, we next examined its effect on HIV-1 founder viruses, which are most likely the ones transmitted during sexual intercourse [34]. We found that SEVI and pooled SE enhance the infectiousness of HIV-1 particles pseudotyped with envelope glycoproteins derived from 25 different transmitted/founder viruses [34] in single round infection assays by 5- to 48 fold (Figure 4A). Notably, the magnitudes of infectivity enhancement by SEVI and SE correlated significantly (p = 0.0006) (Figure 4B). To further examine the effect of SE on viral particles generated by the relevant producer cells in vivo we harvested HIV-1 from ex vivo infected testis tissue [29,31]. We found that SE clearly increases the infectiousness of testis-derived R5- and X4-tropic HIV-1 strains (Figure 4C). Further experiments using luciferase reporter viruses showed that SE also promotes HIV-1 infection of primary T cells and macrophages, the relevant target cells of HIV-1 in vivo (Figure 4D and 4E). Finally, we examined whether SE also affects HIV-1 infection in trans. Our results showed that SE increases the transmission of R5-tropic HIV-1 from non-permissive CaSki human cervical epithelial carcinoma cells to susceptible T cells about 80-fold (Figure 4F). Typically, the strongest enhancing effects of SE were observed with low doses of freshly produced highly infectious HIV-1 virions, irrespective of the virus strain and producer or target cell type.

Bottom Line: Despite its importance for the global spread of HIV-1, however, the effect of semen on virus infection is controversial.We show that semen rapidly and effectively enhances the infectivity of HIV-1, HIV-2, and SIV.Our results show that semen strongly enhances the infectivity of HIV-1 and other primate lentiviruses and that SEVI contributes to this effect.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Molecular Virology, University Hospital Ulm, 89081 Ulm, Germany.

ABSTRACT

Background: HIV-1 is usually transmitted in the presence of semen. We have shown that semen boosts HIV-1 infection and contains fragments of prostatic acid phosphatase (PAP) forming amyloid aggregates termed SEVI (semen-derived enhancer of viral infection) that promote virion attachment to target cells. Despite its importance for the global spread of HIV-1, however, the effect of semen on virus infection is controversial.

Results: Here, we established methods allowing the meaningful analysis of semen by minimizing its cytotoxic effects and partly recapitulating the conditions encountered during sexual HIV-1 transmission. We show that semen rapidly and effectively enhances the infectivity of HIV-1, HIV-2, and SIV. This enhancement occurs independently of the viral genotype and coreceptor tropism as well as the virus producer and target cell type. Semen-mediated enhancement of HIV-1 infection was also observed under acidic pH conditions and in the presence of vaginal fluid. We further show that the potency of semen in boosting HIV-1 infection is donor dependent and correlates with the levels of SEVI.

Conclusions: Our results show that semen strongly enhances the infectivity of HIV-1 and other primate lentiviruses and that SEVI contributes to this effect. Thus, SEVI may play an important role in the sexual transmission of HIV-1 and addition of SEVI inhibitors to microbicides may improve their efficacy.

Show MeSH
Related in: MedlinePlus