The purpose of this R21 application is to develop a model to test the hypothesis that neutralizing antibodies re-formed during acute hepatitis C virus (HCV) infection. Comprehension of immune responses in acute HCV infection is central to efforts to treat and prevent infection. While there are several studies underway detailing the cellular response to acute infection, there is little information regarding humoral immunity. We have overcome two of the major challenges in researching acute HCV infection by establishing a repository of serum samples taken before, during and after acute infections among young injection drug users and assembling a panel of key HCV antigens to evaluate responses. Using these resources we will characterize the humoral immune response to acute HCV infection, examining the kinetics and specificities of anti-E1 and -E2 glycoprotein responses, as well as IgG class switching. These events will be correlated with liver enzyme changes, HCV RNA titer, and HCV sequence evolution. We have established 5.2kb clones representing the major and minor viral variants and have sequenced the major variants at the onset of viremia and 6 months thereafter for 18 individuals. These reagents and the corresponding serum repository provide the rare opportunity to examine strain specific responses. Therefore, a second aim of this investigation is to construct a pseudotype virus that readily expresses HCV envelope sequences using lentiviral replicative machinery, as has been done recently with other viruses. The hypothesis that antibody to envelope reduces the fitness of individual HCV variants (neutralization) will be examined by expressing the envelope sequences of major and minor variants of 4 or more persons at two time points, beginning with the onset of viremia and 6 months later. In addition, equal numbers of 1a and 1b infected participants will be used for analysis. We will analyze pseudotyped virus by correlating envelope sequence with the ability of serum collected at various times to neutralize its infectivity. We believe there is a high likelihood this research will be successful, but submit the work initially as an R21 to prove the feasibility of the pseudotype system.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21DK068555-01A1
Application #
6925765
Study Section
Special Emphasis Panel (ZRG1-IDM-G (90))
Program Officer
Doo, Edward
Project Start
2005-05-01
Project End
2007-04-30
Budget Start
2005-05-01
Budget End
2006-04-30
Support Year
1
Fiscal Year
2005
Total Cost
$203,437
Indirect Cost
Name
Johns Hopkins University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21218
Dowd, Kimberly A; Hershow, Ronald C; Yawetz, Sigal et al. (2008) Maternal neutralizing antibody and transmission of hepatitis C virus to infants. J Infect Dis 198:1651-5
Pandey, Janardan P; Luo, Yuqun; Elston, Robert C et al. (2008) Immunoglobulin allotypes influence IgG antibody responses to hepatitis C virus envelope proteins E1 and E2. Hum Immunol 69:158-64
Netski, Dale M; Mosbruger, Tim; Astemborski, Jacquie et al. (2007) CD4+ T cell-dependent reduction in hepatitis C virus-specific humoral immune responses after HIV infection. J Infect Dis 195:857-63
Netski, Dale M; Mosbruger, Tim; Depla, Erik et al. (2005) Humoral immune response in acute hepatitis C virus infection. Clin Infect Dis 41:667-75