Who cares about arenaviruses?

GHIRINGHELLI, P.D., LOZANO M., ALBARIÑO, C., POSIK, D., TORTORICI M.A. Y ROMANOWSKI, V.

Caldas Novas, GO, Brasil.

Congreso; 12th National Meeting of Virology and 4th Mercosul meeting of Virology.; 2001

Arenaviruses are enveloped and package non­equimolar amounts of each genomic RNA species (L and S RNAs) and variable numbers of ribosomes as they bud from the plasma membrane of the infected cells. The genetic reassortment in dually infected cells has been recognized as a major source for genetic variation, and the formation of heterodiploid virions leads to the possibility of evolutionary experiments. More recently, evidence has emerged that suggests the occurrence of RNA recombination. Although the financial resources dedicated to arenavirus research have been shrinking some interesting findings in the field of molecular genetics have been recently reported based on a combination of experimental approaches, including RT-PCR, gene expression and reverse genetics. Some of the arenaviruses have been recognized as etiological agents for serious human diseases. The common feature of these diseases is their restricted geographical distribution and the emerging character of the first outbreaks. In particular, Junín virus has ben recognized in the late fifties as the etiological agent of Argentine hemorrhagic fever (AHF). Initially, more than 30% AHF cases had a fatal outcome. These figures were reduced to less than 1% by early immune therapy. Therefore, early and rapid diagnosis is extremely important. The molecular cloning of Junín virus cDNA yielded nucleotide sequence information that was quickly used to develop and validate a RT-PCR-based diagnostic assay. An extension of this methodology was also used to detect and characterize new arenaviruses in field rodents trapped in Argentina. The sequence of the first 2.9 kb of the S RNA of one of these isolates, designated Río Caracarañá (RCÑ), is highly homologous to Junín virus genome (90%), whereas the remaining 0.5 kb exhibit a 96% identity with Oliveros virus. Junín and Oliveros belong to two different lineages recognized among the New World Arenaviruses and the RCÑ sequence data strongly suggest that true RNA recombination may occur in nature. Similar observations have been made on the origin of Whitewater Arroyo virus (WWA) isolated in North America. This and other genetic variation mechanisms may lead to the adaptation of the viruses to new hosts and eventual emergence of human disease by acquisition of particular genetic traits. The number of members of the Arenaviridae will probably continue to grow thanks to genetic variation and to the use of sensitive detection and analysis techniques. Within this framework, it is possible to speculate that emergence or re­emergence of human infections could be minimized with the help of careful molecular-epidemiological surveillance programs.