Testicular Tissue Harbors HIV

November 27, 2006

RENNES, France -- HIV can infect immune cells in the testis and produce infectious viral particles that, in turn, can re-infect cells in the blood, according to French researchers.

RENNES, France, Nov. 27 -- HIV can infect immune cells in the testis and produce infectious viral particles that, in turn, can re-infect cells in the blood, according to French researchers.

The finding is significant because the testis is a pharmacological sanctuary that anti-retroviral drugs have difficulty penetrating, said to Nathalie Dejucq-Rainsford, Ph.D., of the French national institute of health and medical research (INSERM) in Rennes.

In other words, even when HIV patients undergoing highly active antiretroviral therapy (HAART) have undetectable levels of the HIV in their blood, their testes may be harboring the virus, Dr. Dejucq-Rainsford and colleagues commented.

The cells involved are macrophages in the interstitial tissue of the organ that express the protein CD68, the researchers reported in the December issue of the American Journal of Pathology.

Dr. Dejucq-Rainsford and colleagues used a novel culture system in which they were able to take tissue from testes removed during prostate cancer surgery and maintain the same tissue architecture as found in the in vivo organ.

On the first day of culture, the researchers were able to establish that cells expressing the necessary HIV receptors -- CD4, CXCR4, and CCR5 -- were found in the interstitial tissue, but not in seminiferous tubules or peritubular cells.

Cells expressing CD4 represented on average about 8% of all the interstitial cells, while CXCR4-positive cells and CCR5-positive cells made up about 3% and 4%, respectively, and the proportions stayed the same throughout 16 days of culture.

When the researchers exposed the tissue culture to a dual-tropic HIV-1 strain, they observed a significant increase in viral RNA and a parallel increase in the activity of viral reverse transcriptase, "indicating a productive infection."

Specifically, Dr. Dejucq-Rainsford and colleagues said than in the supernatant liquid of the cultures:

  • Reverse transcriptase activity (measured in picograms per milliliter) went from almost non-existent to 10 between day 12 and day 14, a change that was statistically significant at P