For many infectious diseases, the body can mount an antibody response that eliminates the pathogen and leaves behind protective immunity to prevent reinfection. But there is limited information about whether this happens with hepatitis C virus (HCV).

To discover more about this issue, researchers at multiple public health organizations in the Netherlands investigated the occurrence of reinfection and superinfection among HCV seroconverters participating in the Amsterdam Cohort Studies of injection drug users from 1985 through 2005. Technically, superinfection refers to a second infection occurring after an initial pathogen is already present, while coinfection refers to simultaneous infection with 2 or more pathogens.

As described in an oral presentation at the 13th International Symposium on Viral Hepatitis and Liver Disease (ISVHLD) this week in Washington, DC, the investigators tested 59 HCV seroconverters for HCV RNA at 5 different time points: the last visit before seroconversion, the first visit after seroconversion, 6 months after seroconversion, 1 year after seroconversion, and their last follow-up visit.

Viral clearance was defined as 2 consecutive visits, at least 4 months apart, at which they were HCV antibody positive but did not have detectable HCV RNA. If HCV RNA was present, part of the NS5B region was amplified and sequenced. Additional cloning and analysis was performed to establish HCV reinfection and superinfection.

Results

In total, 94 HCV infections were identified:

59 primary infections;

11 reinfections;

23 superinfections

1 coinfection.

Multiple HCV infections were observed in 10 of 25 seroconverters (40%) with viral clearance (40%) and 14 of 34 seroconverters without viral clearance (41%).

Of the 24 seroconverters who experienced multiple HCV infections:

7 had HCV reinfections;

14 had superinfections;

3 had combinations of reinfection, superinfection, and/or coinfection.

4 seroconverters experienced multiple infections of the same HCV subtype.

The number of different HCV infections per seroconverter ranged from 1 to 4.

HCV reinfection persisted in 6 seroconverters.

Based of these results, the investigators concluded that HCV reinfection and superinfection "are common among actively injecting drug users." Further, they stated, "This finding argues against the existence of HCV protective immunity and will further complicate [HCV] vaccine development."

Cluster of Infectious Diseases, Public Health Service, Amsterdam, Netherlands; Department of Medical Microbiology, Academic Medical Center, Amsterdam Netherlands; Center for Infectious Diseases Control, National Institute of Public Health and the Environment, Bilthoven, Netherlands.

3/24/09

Reference
TJW van de Laar, R Molenkamp, CHSB van den Berg, and others. Frequent HCV Reinfection and Superinfection among Injecting Drug Users Argue against HCV Protective Immunity. 13th International Symposium on Viral Hepatitis and Liver Disease (ISVHLD). Washington, DC. March 20-24, 2009. Abstract OP-125 (oral).