NATURALLY-OCCURRING SIN-NOMBRE VIRUS GENETIC REASSORTANTS

Genetic reassortment has been shown to play an important role in the e volution of several segmented RNA viruses and in the epidemiology of a ssociated diseases. Sin Nombre (SN) virus is the cause of hantavirus p ulmonary syndrome throughout the western United States. Like other han taviruses, it possesses a genome consisting of th ree negative-sense R NA segments, S, M, and L. Recent analysis has demonstrated the presenc e of at least three different hantaviruses in Nevada and eastern Calif ornia, including SN, Prospect Hill-like, and El Moro Canyon-like virus es. In addition, two distinct lineages of SN virus can be found in Per omyscus maniculatus rodents (sometimes in close proximity) trapped at study sites in this region. Data obtained by phylogenetic analysis of sequence differences detected among the S, M, and L genome segments of these SN viruses are consistent with reassortment having taken place between SN virus genetic variants. The results suggest that M (and to a lesser extent S or L) genome segment flow occurs within SN virus pop ulations in P. maniculatus in this region. No reassortment was detecte d between SN virus and other hantavirus types present in the area. Thi s finding suggests that as genetic distance increases, the frequency o f formation of Viable reassortants decreases, or that hantaviruses whi ch are primarily maintained in different rodent hosts rarely have the opportunity to genetically interact. (C) 1995 Academic Press, Inc.