Epidemiology

GBV-C infection does not protect against CD4+ cell loss or HIV progression

Last Updated: 2005-02-24 15:07:16 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Despite earlier studies suggesting that GB virus C (GBV-C) infection may protect against HIV-1 disease progression, a new study shows no such protection. However, loss of GBV-C, as opposed to its continuous absence, appears to be associated with accelerated progression of HIV-1 disease, investigators report in the Journal of Infectious Diseases for March 1.

There are conflicting reports on what effect GBV-C co-infection has on HIV-1 disease progression. Some research groups have observed a strong association between GBV-C viremia and improved survival in HIV-infected patients (See Reuters Health report Feb. 13), while others have not (See Reuters Health report May 3, 2004).

Dr. Akke K. Van der Bij from the Municipal Health Service of Amsterdam and colleagues studied this issue in 326 men with an established date of HIV-1 seroconversion who were followed for a median of 8 years in The Amsterdam Cohort Studies.

For each participant, researchers tested a first plasma sample obtained at entry shortly after seroconversion and a last serum sample obtained before 1996 for GBV-C RNA and envelope protein-2 antibodies (anti-E2).

Tests on the first samples revealed GBV-C RNA in 137 men (42%) and E2 antibodies, signifying resolved GBV-C viremia, in 134 men (41%). Tests on the last sample revealed GBV-C RNA in 69 men (21%) and E2 antibodies in 126 (39%).

According to the investigators, "men who lost GBV-C RNA between collection of the first sample and collection of the last sample had a nearly 3-fold higher risk of HIV-1 disease progression than did men who never had GBV-C RNA."

However, the negative effect of GBV-C RNA loss on disease progression disappeared when the researchers adjusted for changes in CD4+ cell count, they report. Therefore, it seems that "GBV-C RNA loss is due to CD4+ cell loss, not vice versa," they hypothesize.

Because GBV-C can replicate in CD4+ cells, a drop in CD4+ cells during the course of HIV-1 infection reduces the number of target cells for GBV-C. "This might explain why GBV-C RNA loss is associated with an increased risk of death in HIV-1-infected individuals," the investigators write.

GBV-C infection has been "seriously considered as a potentially protective agent in the fight against HIV-1 disease progression," the authors point out. Based on the current study, they urge caution until further studies are performed in large, well-defined cohorts of HIV-1-infected patients.

J Infect Dis 2005;191:678-685.