Resumen de Characterization of emerging novel human astrovirus: from bedside to bench
We implemented several cell culture systems for the propagation of novel human astrovirus (HAstV) MLB: HAstV-MLB1 and HAstV-MLB2 could be propagated on HuH-7 and A549 cell lines and establish persistent infection. Only a few proportion of cells were infected (5-10%), but the viral titre in the supernatant was high (7-10 log10 genome copies/ml of supernatant). Depending on the cell culture and genotype, we observed no or a delayed and reduced interferon response during acute infection and no interferon response during persistent infection. Similarly, exogenous interferon-β could cure HuH-7 from HAstV MLB1 persistent infection, but had no effect on viral replication in A549 cell lines. In our first epidemiological study, we observed a prevalence of 10% for novel HAstV in stool samples of children < 5 years old with undiagnosed gastroenteritis, with a predominance in children under 2 years old. There was a high rate of co-infection with other enteric viruses (66%), and Cq value was not different between mono- and co-infected cases. In the second epidemiological study, we did not find a difference in the prevalence of novel HAstV when comparing children with undiagnosed gastroenteritis (6.3%) and asymptomatic children (4%). Nevertheless, we found that asymptomatic children had a higher median viral titre (6.52 log10 viral RNA copy number/ml of fecal suspension IQR 4.52-6.84) than symptomatic children (2.35 log10 viral RNA copy number/ml of fecal suspension, IQR 2.13-3.76). We also found that among symptomatic children, novel HAstV viral titre was higher in coproculture-positive cases (5.19 log10 viral RNA copy number/ml of fecal suspension, IQR 4.24-6.22) than in coproculture-negative ones (2.31 log10 viral RNA copy number/ml of fecal suspension, IQR 2.11-3.32). We could not find risk factor that can predict the occurrence of novel HAstV infection.
