Researchers at the St. Louis University Center for Vaccine Development will soon launch a clinical trial of a vaccine designed to prevent hepatitis C infection, the St. Louis Post-Dispatch reports. The human trial, the first of a preventative hepatitis C vaccine, will be conducted in conjunction with biotechnology company Chiron, which developed the vaccine. Researchers will measure the immune system responses to 45 volunteers who are not infected with the hepatitis C virus to gauge whether the compound elicits an antibody response to HCV. The vaccine includes genes from HCV's outer coat that in lab and animal tests have prompted the immune system to build a defense against the actual virus. Hepatitis C can be transmitted through contact with infected blood, and it is possible to acquire it through unprotected sex. It is a common coinfection among HIV-positive gay men and is one of the leading causes of complications and death among people with HIV. Health officials estimate that as many as 4 million Americans are infected with HCV. The chronic disease can cause severe liver damage and death.