Washington: Research has debunked the belief that hepatitis C virus slows down immune system's ability to restore itself after HIV patients are treated with combination drugs known as the 'cocktail'.

Hepatitis C infection is more serious in HIV-infected people, leading to rapid liver damage, according to the Centre for Disease Control.

Intravenous drug use is a main method of contraction for both HIV and hepatitis C. Besides, 50 to 90 percent of HIV-infected drug users are also infected with hepatitis C.

Wake Forest Baptist researchers looked at whether having hepatitis C co-infection impairs immune restoration in patients receiving highly active anti-retroviral therapy (HAART) or 'cocktail' to suppress their HIV infection.

The research focused on levels of CD4 cells, the immune cell that is attacked by the HIV virus, and their ability to rebuild after HIV is suppressed.

"We've been observing that in some patients co-infected with hepatitis C, we were treating their HIV with 'cocktail' but didn't always get very good restoration of CD4," said Marina Nunez, co-author of the paper and an assistant professor of infectious diseases.

"Some studies suggested it was because of the hepatitis C. This study said it's not the presence of active hepatitis C replication.

"From a clinical standpoint, although these findings will not alter the clinical management of HIV-hepatitis C-co-infected patients, they make clear that even after successful treatment of the HCV infection, some patients may still not get an adequate CD4 recovery under HIV treatment."

For the retrospective study, researchers examined existing medical records of 322 patients from two separate databases - one from Madrid and the other from Wake Forest University Baptist Medical Centre.

Patients were separated into two groups - those co-infected with hepatitis C and HIV and those infected only with HIV.

Researchers reviewed CD4 levels before beginning HIV suppression and every year after for up to three years while the patients continuously received HAART, an HIV treatment consisting of three different types of medicines used by many patients, and formerly referred to as the HIV `cocktail'.

Years of clinical experience have shown that, with 'cocktail' treatment suppressing the HIV, CD4 levels are typically able to restore themselves, Nunez said.

The results appeared in the July issue of AIDS Research and Human Retroviruses. IANS