Natural rodent host associations of Guanarito and pirital viruses (Family Arenaviridae) in central Venezuela.

The objective of this study was to elucidate the natural rodent host relationships of Guanarito and Pirital viruses (family Arenaviridae) in the plains of central Venezuela. Ninety-two arenavirus isolates from 607 animals, representing 10 different rodent species, were characterized to the level of serotype. The 92 isolates comprised 19 Guanarito virus strains and 73 Pirital virus strains. The 19 Guanarito virus isolates were from Zygodontomys brevicauda; 72 (98.6%) of the 73 Pirital virus isolates were from Sigmodon alstoni. These results indicate that the natural rodent associations of these 2 sympatric arenaviruses are highly specific and that Z brevicauda and S. alstoni are the principal rodent hosts of Guanarito and Pirital viruses, respectively.

Isolation and characterization of pirital virus, a newly discovered South American arenavirus.

Specific rodent species are principal hosts for each of the well-characterized members of the virus family Arenaviridae. Guanarito virus (Arenaviridae) is the etiologic agent of Venezuelan hemorrhagic fever. A previous study on the epidemiology of Venezuelan hemorrhagic fever revealed extensive arenavirus infection (presumed to be caused by Guanarito virus) in two rodent species. Sigmodon alstoni and Zygodontomys brevicauda, collected from the region of Venezuela in which the disease is endemic. In the present study, four arenavirus isolates recovered from the Municipality of Guanarito (two isolates each from S. alstoni and Z. brevicauda) were characterized to learn more about the natural rodent host relationships of Guanarito virus. Serologic tests and analyses of nucleocapsid protein gene sequence data indicated that the two isolates from Z. brevicauda are strains of Guanarito virus and that the two isolates from S. alstoni are representatives of a novel New World arenavirus (proposed name Pirital) that is antigenically and phylogenetically distinct from all known New World arenaviruses. The results of the present study provide further evidence that the cane mouse Z. brevicauda is a natural host of Guanarito virus and suggest that the cotton rat S. alstoni is the natural reservoir host of Pirital but not Guanarito virus.

Isolation, characterization and geographic distribution of Caño Delgadito virus, a newly discovered South American hantavirus (family Bunyaviridae).

Rodents collected from the Venezuelan llanos (plains) during field studies of viral hemorrhagic fever were tested for evidence of hantavirus infection. Hantavirus antibody was found in one (7.7%) of 13 Oryzomys bicolor, one (3.4%) of 29 Rattus rattus, 10 (6.0%) of 166 Sigmodon alstoni and one (2.2%) of 45 Zygodontomys brevicauda. Hantavirus-specific RNA was detected in lung tissues from four antibody-positive rodents: two S. alstoni from Portuguesa State and one S. alstoni each from Cojedes and Barinas States. A hantavirus isolate (herein identified as VHV-574) was recovered from lung tissue from a hantavirus RNA-positive S. alstoni collected from Portuguesa State. The results of serological tests and analyses of small and medium RNA segment nucleotide sequence data indicated that VHV-574 represents a novel hantavirus (proposed name 'Caño Delgadito') that is distinct from all previously characterized hantaviruses. The results of analyses of nucleotide sequence data from the four hantavirus RNA-positive S. alstoni suggested that Caño Delgadito virus is widely distributed in the Venezuelan llanos.

Field studies on the epidemiology of Venezuelan hemorrhagic fever: implication of the cotton rat Sigmodon alstoni as the probable rodent reservoir.

During February 1992, field studies on the epidemiology of Venezuelan hemorrhagic fever (VHF) were carried out in a rural area of Portuguesa State in central Venezuela. The objective of this work was to determine the prevalence of infection with Guanarito virus, the etiologic agent of VHF, among wild rodents and humans living within an endemic focus of the disease. A total of 234 rodents, representing nine different species, were collected and their spleens were cultured for virus. Thirty-one Guanarito virus isolates were made from two rodent species: 19 from 40 Sigmodon alstoni and 12 from 106 Zygodontomys brevicauda. Guanarito virus antibody rates among these two species were 5.1% and 15.0%, respectively. Nine of the 12 Z. brevicauda that yielded virus from their spleens also had Guanarito virus antibodies in their sera. In contrast, none of the 19 Guanarito virus-positive S. alstoni had antibodies to the virus. These data suggest that S. alstoni usually develops a persistent nonimmunizing infection with Guanarito virus, while Z. brevicauda develops an immunizing infection. Based on knowledge of the behavior of other human pathogenic arenaviruses, these results imply that S. alstoni is the principal rodent reservoir of Guanarito virus in nature. To determine the prevalence of Guanarito virus infection among humans in the same region, 195 people living near one of the rodent collecting sites were bled and their sera were tested for antibodies to the virus. Five individuals (2.6%) had Guanarito virus antibodies; all were adults, and two had been diagnosed previously as having VHF.(ABSTRACT TRUNCATED AT 250 WORDS)