[1] Chulalongkorn Univ, Fac Med, Dept Pediat, Viral Hepatitis Res Unit, Bangkok 10330, Thailand
[2] Chulalongkorn Univ, Fac Grad Studies, Interdept Microbiol, Bangkok 10330, Thailand
[3] Mahidol Univ, Fac Vet Sci, Nakhon Pathom 73170, Nakornphathom P, Thailand