[1] CTR DIS CONTROL & PREVENT, NATL CTR INFECT DIS, DIV VIRAL & RICKETTSIAL DIS, ATLANTA, GA 30333 USA
[2] RUSSIAN STATE RES CTR VIROL & BIOTECHNOL VECTOR, NOVOSIBIRSK 633159, RUSSIA
[3] EMORY UNIV, SCH MED, DEPT MICROBIOL & IMMUNOL, ATLANTA, GA 30322 USA
[4] UNIV NEVADA, DEPT MICROBIOL, RENO, NV 89557 USA