Development of a novel plaque reduction neutralisation test for hantavirus infection

In the Americas, hantaviruses cause severe cardiopulmonary syndrome (HCPS) with a high fatality rate. Hantavirus infection is commonly diagnosed using serologic techniques and reverse transcription-polymerase chain reaction. This paper presents a novel plaque reduction neutralisation test (PRNT) for detecting antibodies to Brazilian hantavirus. Using PRNT, plaque detection was enhanced by adding 0.6% of dimethyl sulfoxide into the overlay culture medium of the infected cells. This procedure facilitated clear visualisation of small plaques under the microscope and provided for easy and accurate plaque counting. The sera from 37 HCPS patients from the city of Ribeirão Preto, Brazil was evaluated for the Rio Mamoré virus (RIOMV) using PRNT. Six samples exhibited neutralising antibodies; these antibodies exhibited a low titre. The low level of seropositive samples may be due to fewer cross-reactions between two different hantavirus species; the patients were likely infected by Araraquara virus (a virus that has not been isolated) and RIOMV was used for the test. This assay offers a new approach to evaluating and measuring neutralising antibodies produced during hantavirus infections and it can be adapted to other hantaviruses, including viruses that will be isolated in the future.

Antibody levels to hantavirus in inhabitants of western Santa Catarina State, Brazil / Níveis de anticorpos para hantavírus em habitantes da região Oeste de Santa Catarina, Brasil

Hantavirus cardiopulmonary syndrome (HCPS) is an infectious disease caused by hantaviruses of the family Bunyaviridae, and is transmitted by aerosols of excreta of infected rodents. The aim of the present study was to determine antibody levels to hantavirus in the population that lives at frontier of Brazil and Argentina. Participated of the study 405 individuals living in the municipalities of Bandeirante, Santa Helena, Princesa and Tunapolis, state of Santa Catarina, Brazil. IgG antibodies to hantavirus were analyzed in sera by an ELISA that uses a recombinant N protein of Araraquara hantavirus as antigen. The results were also confirmed by immunofluorescent test. Eight individuals showed antibodies to hantavirus (1.97% positivity), with serum titers ranging from 100 to 800. Six seropositives were males, older than 30 years and farmers. Our results reinforce previous data on hantavirus circulation and human infections in the southern border of Brazil with Argentina.

Síndrome Cardiopulmonar por Hantavírus (HCPS) é uma doença emergente, causada pelo gênero hantavírus membro da família Bunyaviridae, e são transmitidos aos humanos por aerossol de roedores infectados. O objetivo principal deste estudo foi determinar os níveis de anticorpos para hantavírus em uma população de residentes na fronteira do Brasil com a Argentina. Participaram deste estudo 405 indivíduos que moravam nos municípios de Bandeirante, Santa Helena, Princesa e Tunapólis, no estado de Santa Catarina, Brasil. Os anticorpos IgG para hantavírus foram analisados no soro por um ELISA que usa a nucleoproteína recombinante do vírus Araraquara como antígeno, posteriormente confirmados por imunofluorescência. Oito indivíduos apresentavam anticorpos para hantavírus (1.97% positivo), com titulo entre 100 a 800. Seis soropositivos foram homens, com idade superior a 30 anos e agricultores. Nossos resultados reforçam a circulação do hantavírus e infecção humana na fronteira do Brasil com a Argentina.