engleski

Comparative phylogenetic analysis of norovirus from shellfish and patients with gastroenteritis in Croatia

Norovirus, genus in the family Caliciviridae, is a leading cause of viral gastrointenteritis in humans and is responsible for many outbreaks worldwide. Among six established genogroups (GI to GVI), GII strains are responsible for almost 90% of clinical cases (with a high prevalence of the GII.4 cluster), while the other 10% are caused by GI strains. The aim of this study was to evaluate phylogenetic similarity of norovirus obtained from patients with gastroenteritis and norovirus from shellfish collected in Croatian production areas. During March and April 2014, 23 human stool samples were ELISA tested positive. Seven randomly selected stool samples and 99 shellfish samples were analyzed using real-time RT-PCR for NoV GI and GII with primers directed towards the ORF1-ORF2 junction region for both genotypes. Virus extraction efficiency was calculated with mengovirus and it was acceptable (>1%). Following the phylogenetic characterization of the human stool samples, five out of seven belonged to GII.4 which confirmed the circulation of epidemiological strain Hu/GII.4/sydney/NSW05 (100% similarity). One stool sample showed 97, 6% similarity to genotype II.2 - Snow Mountain strain and for one we didn¨t get a good sequencing fragment. 12 out of 99 shellfish samples tested real-time RT-PCR positive and two were successfully sequenced clustered to genotype GII.4 showed 97, 1% and 98, 5% similarity with Hu/GII.4/sydney/NSW05. Here we describe the emergence of norovirus strains genetically related to Sydney2012 during the 2014 season in Croatia, providing the first evidence of that strain in Croatia. The circulating genotype found in the present study differ from results obtained previously in wich GII.4 Lordsdale was the dominant circulating genotype in Croatia during the season 2004/2005. Norovirus GII.4 in shellfish originating from Croatian production areas is determined simultaneously for the first time in Croatia. That contributes to the knowledge of norovirus contamination in shellfish worldwide. Although outbreaks related to consumption of shellfish in Croatia were not notified, it is well known that human sewage is a possible source of shellfish contamination. Understanding the transmission route and vehicle of a norovirus outbreak is of great public health importance and these results implicate co-circulation of different strains of NoV GII.4 in Croatia

norovirus ; shellfish ; stool samples ; real-time RT-PCR

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