Genetic diversity, distribution, and serological features of hantavirus infection in five countries in South America

Since 1995 when the first case of hantavirus pulmonary syndrome (HPS) was r eported in Patagonia, there have been more than 400 cases of HPS reported i n five countries in South America. The first case of HPS was associated wit h Andes (AND) virus. In this study, we report on the genetic diversity, geo graphical distribution, and serological features of hantavirus infection in six countries in South America based on 87 HPS cases from Argentina, Boliv ia, Chile, Paraguay, and Uruguay. An early immunoglobulin M (IgM), IgA, and IgG humoral response was observed in almost all HPS cases. The IgM respons e appears to peak 1 or 2 days after the onset of symptoms. Peak IgG antibod y titers occur mostly after the first week. Low IgG titers or the absence o f IgG was associated with higher mortality rates. The IgA response peaks ar ound day 15 and then rapidly decreases. The results of phylogenetic analysi s based on partial M-fragment G1- and G2-encoding sequences showed that HPS cases from the five countries were infected with viruses related to AND or Laguna Negra (LN) virus. Within AND virus-infected persons, at least five major genetic lineages were found; one lineage was detected in Uruguayan an d Argentinean cases from both sides of the Rio de la Plata river. Two Parag uayan patients were infected with a virus different from LN virus. Accordin g to the results of phylogenetic analyses, this virus probably belongs to a distinct lineage related more closely to the AND virus than to the LN viru s, suggesting that there is probably an Oligoryzomys-borne viral variant ci rculating in Paraguay. These studies may contribute to a better understandi ng of hantavirus human infection in South America.