Genetic and biological characterisation of Zika virus isolates from different Brazilian regions

BACKGROUND Zika virus (ZIKV) infections reported in recent epidemics have been linked to clinical complications that had never been associated with ZIKV before. Adaptive mutations could have contributed to the successful emergence of ZIKV as a global health threat to a nonimmune population. However, the causal relationships between the ZIKV genetic determinants, the pathogenesis and the rapid spread in Latin America and in the Caribbean remain widely unknown. OBJECTIVES The aim of this study was to characterise three ZIKV isolates obtained from patient samples during the 2015/2016 Brazilian epidemics. METHODS The ZIKV genomes of these strains were completely sequenced and in vitro infection kinetics experiments were carried out in cell lines and human primary cells. FINDINGS Eight nonsynonymous substitutions throughout the viral genome of the three Brazilian isolates were identified. Infection kinetics experiments were carried out with mammalian cell lines A549, Huh7.5, Vero E6 and human monocyte-derived dendritic cells (mdDCs) and insect cells (Aag2, C6/36 and AP61) and suggest that some of these mutations might be associated with distinct viral fitness. The clinical isolates also presented differences in their infectivity rates when compared to the well-established ZIKV strains (MR766 and PE243), especially in their abilities to infect mammalian cells. MAIN CONCLUSIONS Genomic analysis of three recent ZIKV isolates revealed some nonsynonymous substitutions, which could have an impact on the viral fitness in mammalian and insect cells.

Diagnóstico e estudo sorológico da infecção pelo parvovírus canino em cães de Passo Fundo, Rio Grande do Sul, Brasil / Diagnosis and serological study of canine parvovirus infection in dogs from Passo Fundo, Rio Grande do Sul, Brazil

A reação em cadeia da polimerase (PCR) e o ensaio de hemaglutinação (HA) foram comparados para a identificação de parvovírus canino (CPV) em fezes de cães com gastrenterite. A prevalência de anticorpos anti-CPV em uma população de cães sem histórico de vacinação foi avaliada pelo ensaio de inibição da hemaglutinação (HI). A variabilidade fenotípica entre uma amostra vacinal e isolados de campo foi investigada utilizando soro hiperimune. Trinta amostras fecais foram obtidas de cães com diarréia e submetidas à PCR e ao HA, e 185 amostras de soro de cães foram submetidas à HI para detectar anticorpos anti-CPV. Considerando-se somente como positivas as amostras que apresentaram HA na diluição igual ou superior a 1:64, detectou-se CPV em 9 (30 por cento) das amostras fecais. Nove amostras fecais apresentaram HA nas diluições entre 1:2 e 1:32 e foram consideradas negativas nesse teste. Todas as amostras que apresentaram HA na diluição igual ou superior a 1:64 foram positivas pela PCR e, das nove amostras que apresentaram HA nas diluições entre 1:2 e 1:32, seis também foram positivas para CPV na amplificação pela PCR. A pesquisa sorológica de amostras de soros caninos indicou que 178 (96,2 por cento) cães tiveram contato prévio com o vírus. Os soros hiperimunes produzidos em cobaias contra a cepa vacinal e dois isolados de campo indicaram possíveis diferenças fenotípicas entre isolados.

The polymerase chain reaction (PCR) and hemaglutination (HA) assay were used to detect canine parvovirus (CPV) in feces from young dogs with gastroenteritis. The hemaglutination inhibition (HI) assay was used to detect the prevalence of anti-CPV antibodies in a non-vaccinated dog population. In addition, hiperimmune serum was used to investigate the phenotypic variability of a vaccine strain and two field isolates of CPV. Thirty fecal samples obtained from dogs with diarrhea were submitted to PCR and HA, and 185 serum samples were submitted to HI to detect anti-CPV antibodies. Nine (30 percent) of the samples demonstrated HA on fecal dilutions equal to or above 1:64 and were considered positive by this test; nine (30 percent) fecal samples had HA activity on dilution from 1:2 to 1:32 and were considered negative, and the remaining samples were negative. All samples with HA activity at dilutions above 1:64 were also positive to PCR and, out of the nine samples with HA activity at dilutions between 1:2 and 1:32, six were also positive by PCR. Serological analysis of the dog serum samples indicated that 178 (96,2 percent) of the dogs had previous contact with the virus. Hiperimmune serum indicated possible phenotypic differences among isolates, in that different HI titers were obtained following cross-HI assay.