Mary Dutki

Viral load in individuals recently infected with HIV is closely related to that of the individual who transmitted the virus. According to study investigators in the US, "we found a strong correlation between HIV-1 RNA levels in source and recipient partners in HIV-1 transmission pairs".

Viral load a measurement of the amount of HIV in the blood predicts the risk of subsequent disease progression and is thus used to guide treatment decisions and monitor response to treatment. Although the importance of viral load in predicting subsequent disease progression is well established, the factors that influence the viral load during early infection have been poorly understood; therefore a study was conducted to determine the relationship between viral load levels in source partners and recently infected recipient partners within transmission pairs.

The study identified 24 patients with evidence of recent infection. These patients provided information about the individuals they believed had transmitted HIV to them. A total of 23 source individuals were identified and included in the study. Phylogenetic analysis was performed using nucleotide sequences of all suspected partner pairs to determine whether there was viral genetic evidence that the virus in a suspected source partner was closely related to virus in a recipient partner.

In each pair transmission was sexual and between two male partners. The recently infected individuals had a median CD4 cell count of 528cells/mm3 and a median viral load of 86,332 copies/ml. Median CD4 cell count in the source individuals was 372 cells/mm3 and their median viral load was 23,951 copies/ml. Nine of the sources had evidence of recent infection adding to previous research suggesting that recently infected, and therefore undiagnosed individuals, are of key importance to the continuing HIV epidemic.

Statistical analysis showed that viral load in the source and infected partners were closely correlated, thus suggesting a strong influence of viral genetic factors on HIV-1 RNA level during early HIV infection. The investigators proposed subsequent research to better identify the viral genetic characteristics associated with higher or lower HIV-1 RNA level, and to further understand host immunue responses that shape viral replication fitness over time."