REPLICATION AND TISSUE TROPISM OF THE ALPHAVIRUS SINDBIS IN THE MOSQUITO AEDES-ALBOPICTUS

We have examined the replication and tissue distribution of the alphav irus Sindbis in the mosquito Aedes albopictus. Parenteral inoculation of virus resulted in an acute infection accompanied by rapid virus rep lication and a persistent infection, during which total virus producti on was reduced. Acute and persistent phase virus RNA synthesis, virus production, and organ-specific distribution of infection were determin ed over an 18-day incubation period. Organs were classified as refract ory (ovarioles, Malpighian tubules), cleared (head ganglia), transient (salivary glands, anterior midgut posterior midgut, and thoracic musc le), or persistent (fat bodies-hemolymph, hindgut, and tracheole-assoc iated cells) according to the onset, peak, and duration of Sindbis vir us antigens within that particular organ. Virus was identified in resp iratory tissue by immunological and ultrastructural methods. This repr esents a novel tropism for an alphavirus. These findings demonstrate t hat the cells of mature insect organs respond differently to virus inf ection. Correlations among virus replication, virus RNA synthesis, and organ-specific clearing of a pantropic infection were observed. We su ggest that the underlying temporal and spatial kinetics that character ize this virus-invertebrate interaction may reflect a mechanism for th e modulation of the arbovirus titer seen in the mosquito host. (C) 199 5 Academic Press, Inc.