Analysis of HIV-1 viral load in seminal plasma samples.

BACKGROUND

With HIV-1-infected individuals now facing the prospect of relatively long and healthy lives, many discordant couples (where the male is HIV-1 seropositive) are seeking to have children. To assist reducing the risks of heterosexual and subsequent vertical transmission in this situation, quantification of HIV-1 viral load in seminal plasma may be effective as one of several measures to reduce the risk of infecting the mother during insemination, potentially providing a better indication of infectivity than blood plasma analysis.

OBJECTIVE(S): To modify existing molecular methods for the purpose of analysing HIV-1 viral load in seminal plasma.

METHODS

Two commercial assays for HIV-1 RNA quantification were used to assess their sensitivity, specificity and precision for quantification of seminal plasma samples. Seminal plasma samples were prepared with an additional centrifugation step to aid removal of inhibitors to molecular assays.

RESULTS

Seminal plasma samples exhibited specificity of >95%, equivalent to that reported by the manufacturers of the commercial assays. With additional centrifugation, complete inhibition of 2/19 (10%) seminal plasma samples was observed using the RT-PCR assay, and inhibition was not apparent in the bDNA assay. Quantification of HIV-1 RNA in seminal plasma samples in both assays was equivalent to that observed in plasma samples and did not appear to be affected by the additional centrifugation step.

CONCLUSION

Minor modification of the RT-PCR assay procedure by additional centrifugation of seminal plasma improved the sensitivity of the assay. Inhibition was not apparent with the bDNA assay.