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TUESDAY, July 8 (HealthDayNews) -- Alcohol promotes the proliferation of the hepatitis C virus in human liver cells.

So says an American study in the July issue of Hepatology.

The researchers studied molecular mechanisms in cell cultures to uncover how alcohol aggravates hepatitis C infection and interferes with drug treatment to aid people with the infection.

They found alcohol increases the activity of a protein called nuclear factor kappa B. That causes the hepatitis C virus to produce multiple copies of itself. They also found alcohol interferes with the antiviral activity of the drug interferon-alpha, which is used to treat people infected with hepatitis C.

The researchers also concluded the drug naltrexone -- which is used to help alcoholics avoid relapse -- may block the harmful effects of alcohol in promoting hepatitis C infection.

"It was already known that habitual alcohol drinkers have higher blood levels of hepatitis C virus, compared to infrequent drinkers, even when both are infected with the virus," lead researcher Dr. Wen-Zhe Ho, director of retroviral research at the Children's Hospital of Philadelphia, says in a news release.

"We investigated how alcohol affects the hepatitis C virus at the cellular level. Our study provides a biological mechanism to support clinical observations," Ho says.

About 170 million people worldwide are infected with hepatitis C. It's one of the leading causes of liver disease in the United States.

More information

Here's where you can learn more about hepatitis C.