[1] Lovelace Resp Res Inst, Albuquerque, NM 87108 USA
[2] Hokkaido Univ, Dept Ophthalmol, Grad Sch Med, Kita Ku, Sapporo, Hokkaido 0608638, Japan
[3] Hungarian Acad Sci, Vet Med Res Inst, H-1581 Budapest, Hungary
[4] Univ Glasgow, MRC, Ctr Virus Res, Glasgow G11 5JR, Lanark, Scotland
[5] CEMIC Univ Hosp, Clin Virol Unit, Buenos Aires, DF, Argentina
[6] Ctr Dis Control & Prevent, Atlanta, GA 30303 USA
[7] Umea Univ, S-90185 Umea, Sweden