Minimum infectious dose of hepatitis B virus in chimpanzees and difference in the dynamics of viremia between genotype A and genotype C.
BACKGROUND
In planning optimal hepatitis B virus (HBV) blood screening strategies, the minimum infectious dose and early dynamics of HBV need to be determined for defining the window period for HBV DNA as well as for hepatitis B surface antigen (HBsAg).


METHODS
Pairs of chimpanzees were inoculated with preacute-phase inocula containing HBV of genotype A or genotype C to determine the minimum infectious dose, and two pairs of chimps infected with the lowest infectious dose of genotypes A and C were followed for HBV markers.


RESULTS
The minimum 50 percent chimpanzee infectious dose (CID50) was estimated to be approximately 10 copies for genotype A and for genotype C. In the two chimps inoculated with the lowest infectious dose, the HBV DNA window was 55 to 76 days for genotype A and 35 to 50 days for genotype C, respectively. The HBsAg window was 69 to 97 days for genotype A and 50 to 64 days for genotype C, respectively. The doubling times of HBV DNA were 3.4 days (95% confidence interval [CI], 2.6-4.9 days) for genotype A and 1.9 days (95% CI, 1.6-2.3 days) for genotype C. When comparing the replication velocity of HBV DNA between the two genotypes, the doubling time of genotype C was significantly shorter than that of HBV genotype A (p < 0.01).


CONCLUSIONS
Although the CID50 of approximately 10 copies was similar for the two HBV genotypes, the doubling time and pre-HBV nucleic acid amplification technology (<100 copies/mL) window period in chimps infected with the lowest infectious dose seemed to be shorter for genotype C than for genotype A.
Komiya
Yutaka
Y
Department of Epidemiology, Infectious Disease Control and Prevention, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima, Japan.
Katayama
Keiko
K
Yugi
Hisao
H
Mizui
Masaaki
M
Matsukura
Harumichi
H
Tomoguri
Tetsushi
T
Miyakawa
Yuzo
Y
Tabuchi
Ayako
A
Tanaka
Junko
J
Yoshizawa
Hiroshi
H
D000818:Animals; D004279:DNA, Viral / Q000235:genetics; D005260:Female; D018628:Gene Dosage / Q000235:genetics; D005838:Genotype; D006509:Hepatitis B / Q000635:transmission / Q000821:virology*; D006511:Hepatitis B Antigens / Q000276:immunology; D006515:Hepatitis B virus / Q000235:genetics* / Q000276:immunology; D007201:Indicator Dilution Techniques; D008297:Male; D002679:Pan troglodytes; D014766:Viremia / Q000821:virology*; D014779:Virus Replication
D004279:DNA, Viral; D006511:Hepatitis B Antigens