High-resolution phylogeny providing insights towards the epidemiology, zoonotic aspects and taxonomy of sapoviruses.

The evolution, epidemiology and zoonotic aspects of Sapoviruses (SaV) are still not well explored. In this study, we applied high-resolution phylogeny to investigate the epidemiological and zoonotic origins as well as taxonomic classification of animal and human SaV. Bayesian framework analyses showed an increase in porcine SaV (PoSaV) population dynamics and genetic diversity between 1975 and 1982, resulting in a SaV gene flow and generation of new strains among porcine and human populations. Our results also show the contribution of different animal populations involved in SaV epidemiology and highlight zoonotic aspects, as exemplified by the crucial role that swine, dogs, mink and humans play in SaV spread. Additionally, phylogenetic analysis suggests that bats may play key role in SaV epidemiology. According to our hypothesis, these animals may act as reservoirs or intermediate host species, contributing to viral spread in zoonotic and other epidemiological scenarios and facilitating the generation of new SaV genogroups and genotypes through recombination events. Data from large-scale phylogeny partition based on patristic distance, did not show a correlation between transmission clusters on generation of SaV genogroups, nevertheless we present both important findings about SaV taxonomy and important considerations useful for further taxonomical studies.

Molecular detection and characterization of hepatitis E virus in naturally infected pigs from Brazilian herds.

The aim of this study was to investigate the presence of swine hepatitis E virus (HEV) from pigs of different production categories and from different pig farms in South Brazil. A total of 170 porcine faecal samples from breeder sows, boars, suckling piglets, weaned and growing pigs were collected from 14 pig farms. The faecal samples were screened by nested RT-PCR using primers targeting the ORF2 region of HEV genome. The samples that were positive from this screening were used in a nested RT-PCR targeting the ORF1 region. The screening detected HEV RNA in 62.5% of the pig farms and in 15.3% of the faecal samples. In 15 faecal samples, it was possible to amplify the HEV RNA with both the ORF1 and ORF2 regions. The phylogenetic analyses obtained for both ORFs confirmed that all of the Brazilian swine HEV isolates clustered with genotype 3b, the same genotype described previously in humans in Brazil.

VP6 gene diversity in Brazilian strains of porcine group C rotavirus.

Group C rotavirus (RV-C) has been found in Brazilian pig herds; however, wild-type strains have not yet been characterized. We made a molecular analysis of a region of gene 5 in Brazilian RV-C strains. Stool samples from 11 piglets (diarrheic and with normal consistency) positive for the RV-C VP6 gene in an RT-PCR assay were sequenced. A 270-bp amplicon of nine sequences was analyzed. All sequences showed high identity to the Cowden strain of the porcine RV-C prototype and 81.3 to 94.3% to each other (230 nucleotide fragment). Three Brazilian strains were classified in the Cowden group, while the other six showed higher heterogeneity (84.3 to 87.3%) with the prototype strain. Four clusters were formed in the dendrogram, including one human, one bovine, and two porcine clusters; one of these was formed by the six Brazilian strains described in this study. The Brazilian RV-C strains described here did not show any association with the year of collection, the presence of diarrhea, the age of the pig, or the geographical region of herd origin. This strongly suggests that these heterogeneous strains are widely spread in Brazilian pig herds. We conclude that there is genetic polymorphism in the VP6 gene of porcine RV-C strains in Brazil.

Genetic analysis of the porcine group B rotavirus NSP2 gene from wild-type Brazilian strains.

Group B rotaviruses (RV-B) were first identified in piglet feces, being later associated with diarrhea in humans, cattle, lambs, and rats. In human beings, the virus was only described in China, India, and Bangladesh, especially infecting adults. Only a few studies concerning molecular analysis of the RV-B NSP2 gene have been conducted, and porcine RV-B has not been characterized. In the present study, three porcine wild-type RV-B strains from piglet stool samples collected from Brazilian pig herds were used for analysis. PAGE results were inconclusive for those samples, but specific amplicons of the RV-B NSP2 gene (segment 8) were obtained in a semi-nested PCR assay. The three porcine RV-B strains showed the highest nucleotide identity with the human WH1 strain and the alignments with other published sequences resulted in three groups of strains divided according to host species. The group of human strains showed 92.4 to 99.7% nucleotide identity while the porcine strains of the Brazilian RV-B group showed 90.4 to 91.8% identity to each other. The identity of the Brazilian porcine RV-B strains with outer sequences consisting of group A and C rotaviruses was only 35.3 to 38.8%. A dendrogram was also constructed to group the strains into clusters according to host species: human, rat, and a distinct third cluster consisting exclusively of the Brazilian porcine RV-B strains. This is the first study of the porcine RV-B NSP2 gene that contributes to the partial characterization of this virus and demonstrates the relationship among RV-B strains from different host species.

Genetic analysis of the porcine group B rotavirus NSP2 gene from wild-type Brazilian strains

Group B rotaviruses (RV-B) were first identified in piglet feces, being later associated with diarrhea in humans, cattle, lambs, and rats. In human beings, the virus was only described in China, India, and Bangladesh, especially infecting adults. Only a few studies concerning molecular analysis of the RV-B NSP2 gene have been conducted, and porcine RV-B has not been characterized. In the present study, three porcine wild-type RV-B strains from piglet stool samples collected from Brazilian pig herds were used for analysis. PAGE results were inconclusive for those samples, but specific amplicons of the RV-B NSP2 gene (segment 8) were obtained in a semi-nested PCR assay. The three porcine RV-B strains showed the highest nucleotide identity with the human WH1 strain and the alignments with other published sequences resulted in three groups of strains divided according to host species. The group of human strains showed 92.4 to 99.7 percent nucleotide identity while the porcine strains of the Brazilian RV-B group showed 90.4 to 91.8 percent identity to each other. The identity of the Brazilian porcine RV-B strains with outer sequences consisting of group A and C rotaviruses was only 35.3 to 38.8 percent. A dendrogram was also constructed to group the strains into clusters according to host species: human, rat, and a distinct third cluster consisting exclusively of the Brazilian porcine RV-B strains. This is the first study of the porcine RV-B NSP2 gene that contributes to the partial characterization of this virus and demonstrates the relationship among RV-B strains from different host species.