Low Aedes aegypti Vector Competence for Zika Virus from Viremic Rhesus Macaques.

Despite worldwide efforts to understand the transmission dynamics of Zika virus (ZIKV), scanty evaluation has been made on the vector competence of Aedes aegypti fed directly on viremic human and non-human primates (NHPs). We blood-fed Ae. aegypti from two districts in Rio de Janeiro on six ZIKV infected pregnant rhesus macaques at several time points, half of which were treated with Sofosbuvir (SOF). Mosquitoes were analyzed for vector competence after 3, 7 and 14 days of incubation. Although viremia extended up to eight days post monkey inoculation, only mosquitoes fed on the day of the peak of viremia, recorded on day two, became infected. The influence of SOF treatment could not be assessed because the drug was administered just after mosquito feeding on day two. The global infection, dissemination and transmission rates were quite low (4.09%, 1.91% and 0.54%, respectively); no mosquito was infected when viremia was below 1.26 × 105 RNA copies/mL. In conclusion, Ae. aegypti vector competence for ZIKV from macaques is low, likely to be due to low viral load and the short duration of ZIKV viremia in primates suitable for infecting susceptible mosquitoes. If ZIKV infection in human and macaques behaves similarly, transmission of the Zika virus in nature is most strongly affected by vector density.

Sofosbuvir shows a protective effect against vertical transmission of Zika virus and the associated congenital syndrome in rhesus monkeys.

The outbreaks of Zika virus (ZIKV) infection in Brazil, 2015-2016, were associated with severe congenital malformations. Our translational study aimed to test the efficacy of the antiviral agent sofosbuvir (SOF) against vertical transmission of ZIKV and the associated congenital syndrome (CZS), using a rhesus monkey model. Eight pregnant macaques were successfully infected during the organogenesis phase with a Brazilian ZIKV strain; five of them received SOF from two to fifteen days post-infection. Both groups of dams showed ZIKV-associated clinical signals, detectable ZIKV RNA in several specimens, specific anti-ZIKV IgM and IgG antibodies, and maternal neutralizing antibodies. However, malformations occurred only among non-treated dam offspring. Compared to non-treated animals, all SOF-treated dams had a shorter ZIKV viremia and four of five neonates had undetectable ZIKV RNA in blood and tissue samples. These results support further clinical evaluations aiming for the prevention of CZS.

Serological and virological survey of hepatitis E virus (HEV) in animal reservoirs from Uruguay reveals elevated prevalences and a very close phylogenetic relationship between swine and human strains.

Hepatitis E virus (HEV) infection is an issue of public health concern in high-income and non-endemic countries. Increasing evidence supports the hypothesis of a zoonotic route as the main mode of infection in this epidemiological setting, since the transmission of genotypes HEV-3 and HEV-4 from reservoirs to humans has been demonstrated. In America, studies have confirmed the circulation of HEV in pig herds but the zoonotic role of wild boars has never been evaluated. Uruguay has a high burden of HEV- associated acute hepatitis, and a close phylogenetic relationship was observed among human HEV-3 strains and European isolates detected in swine. However in this context, swine herds have never been surveyed. Herein is reported a survey of HEV in swine herds, pigs at slaughter-house and free-living wild boar populations. Two-hundred and twenty sera and 150 liver tissue samples from domestic pigs, and 140 sera from wild boars were tested for HEV by ELISA and PCR-based approaches. All tested swine farms resulted seropositive with an overall rate of 46.8%. In turn, 22.1% of the wild boars had anti-HEV antibodies. HEV RNA was detected in 16.6% and 9.3% of liver samples from slaughter-age pigs and adult wild boars sera, respectively. Three strains from domestic pig were also amplified by nested-PCR approaches. By contrast, none of the positive samples obtained from wild boars could be confirmed by nested-PCR. Phylogenetic analysis revealed a very high nucleotide identity among swine strains and sequences obtained from humans in Uruguay. Results showed that HEV is widely distributed among swine herds in Uruguay. Additionally, this study evidences for the first time in the American continent that wild boar populations are a reservoir for HEV, though its zoonotic role remains to be elucidated. Altogether, data presented here suggest a high zoonotic risk of HEV transmission from swine to humans.

High frequency of porcine norovirus infection in finisher units of Brazilian pig-production systems.

Norovirus (NoV) is a member of the Caliciviridae family and is considered an emerging human enteric pathogen. NoVs are detected in farm animals such as cattle, sheep and pigs. Porcine NoV (PoNoV) is widespread worldwide, but frequency of infection is often low. This study aimed to investigate the natural PoNoV infection from adult animals of an important Brazilian pig-production region. Faecal samples (n = 112) of asymptomatic pigs aged 9 to 24 weeks old were collected from 16 grower-to-finish herds located in Paraná state, Brazilian Southern region, and evaluated for PoNoV presence. A reverse transcription-polymerase chain reaction (RT-PCR) assay was performed using specific primers that target a conserved region of the virus capsid gene (VP1). PoNoV was detected in 58 (51.8%) of the 112 faecal samples and in 14 (87.5%) of the 16 herds evaluated. Six of the obtained amplicons were submitted to phylogenetic genotyping analysis. The higher nucleotide (86.5-97.4%) and amino acid (100%) similarities of the sequences in this study were with the representative strains of the porcine NoV genogroup II genotype 11 (PoNoV GII-11). These results reveal that PoNoV infection is endemic in one of the most important pork production areas of Brazil and that the PoNoV GII-11 is prevalent in this region.