Measurements of HIV viral loads from different levels of the respiratory tract.

Background: The lung is a common site of disease in HIV infection. Virus has been detected in BAL fluid (BALF) and saliva. However, the relationship between viral loads detected at different levels of the respiratory tract is unknown.

Method: We measured simultaneous HIV viral loads in parotid saliva (PS), bronchial fluid (BF), BALF, and plasma by reverse transcription polymerase chain reaction in 20 HIV-infected individuals.

Results: HIV was detected in 53% of BALF samples, 15% of BF samples, 5% of PS samples, and 88% of plasma samples. Viral loads in plasma and BALF samples were positively correlated. There were significantly higher levels of HIV viral load in both plasma and BALF in subjects with CD4 counts of < 200 cells/ microL compared to those with higher counts. Antiretroviral therapy (ART) was associated with lower BALF and plasma viral loads, and the effect in BALF was independent of the plasma viral load. Interestingly, smoking also was associated with lower levels of both BAL and BF viral loads, independent of the plasma viral load.

Conclusion: These data demonstrate that while HIV can be detected in the respiratory tract, the viral load is influenced by both local factors (ie, level of the respiratory tree and cigarette smoking) and systemic factors (ie, ART and peripheral CD4 count).