SUMMARY: A common but little known set of viruses -- torque teno virus (TTV) and torque teno mini virus (TTMV) -- occur more often in HIV/HCV coinfected individuals than in healthy blood donors, and have been linked to worse liver inflammation and fibrosis progression, according to a poster presented at the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2010) last week in Boston.

By Liz Highleyman

TTV and TTVM are small, genetically variable DNA viruses that are ubiquitous in humans worldwide. They have not been definitively shown to be the cause of any particular diseases, but some research suggests a potential link with liver disease, cancer, and autoimmune conditions such as lupus.

M. Garcia-Alvarez from Instituto de Salud Carlos III in Madrid and colleagues sought to learn more about the prevalence and clinical significance of TTV and TTMV in HIV/HCV coinfected people.

The researchers conducted a cross-sectional study that included 245 coinfected patients who underwent liver biopsy prior to starting hepatitis C treatment, as well as 100 healthy HIV and HCV negative blood donors.

Results

	The prevalence of both TTV (94% vs 83%; P = 0.002) and TTMV (95% vs 72%; P < 0.001) was significantly higher among HIV/HCV coinfected patients compared with healthy blood donors.
	In addition, among people who carried TTV and/or TTMV, viral loads of these 2 viruses were higher in HIV/HCV coinfected people compared with the blood donors:
	TTV: about 7000 vs about 150 copies/mL, respectively (P < 0.001); TTMV: about 900 vs about 25 copies/mL, respectively (P < 0.001).
	Among the coinfected patients, there was an association between higher levels of TTV and/or TTMV and worse liver disease.
	Coinfected patients with TTV viral load at the 75th percentile or above (about 600 copies/mL) had more than twice the risk of severe necro-inflammatory activity (A3 or higher) and advanced fibrosis (F3 or higher) (odds ratios 2.42 and 2.29, respectively).
	Those with TTMV viral load at the 75th percentile or above (about 75 copies/mL) were significantly less likely to have absent necro-inflammatory activity (< A1) and no significant fibrosis (< F1) (odds ratios 0.41 and 0.36, respectively).

"We found a high prevalence of both TTV and TTMV infections in HIV/HCV positive patients," the researchers concluded. "We also found an association between higher viral load of TT viruses and higher activity grades and fibrosis stages in liver biopsies."

"Further work should be done to assess the contribution of TT viruses to liver disease progression in HIV/HCV positive patients," they recommended.

Investigator affiliations: Inst. de Salud Carlos III, Majadahonda, Madrid, Spain; Hosp. Gen. Universitario Gregorio Maranon, Madrid, Spain.

9/21/10

Reference
M Garcia-Alvarez, J Berenguer, P Miralles, and others. Torque Teno Virus (TTV) and Torque Teno Mini Virus (TTMV) in HIV/HCV Co-Infected Patients: Prevalence and Role in Liver Disease. 50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC 2010). Boston, September 12-15, 2010. (Abstract H-1675).