engleski

The emergence of porcine epidemic diarrhoea in Croatia: molecular and serological investigation

Background Porcine Epidemic Diarrhoea (PED) is an emergent/reemergent viral disease (family Coronaviridae, genus Alphacoronavirus) of pigs with worldwide importance. Clinical appearance is characterized by acute diarrhoea, vomiting and dehydration in all age categories with possible high mortality in suckling piglets. The disease got a lot of media attention in 2013 when it emerged in the USA causing heavy production losses (highly pathogenic non-S-INDEL genotype). Since 2014 PED has reemerged in Europe spreading around western European countries, but causing milder consequences. The causative agent responsible for European outbreaks (apart from Ukraine) is S-INDEL PEDV genotype which represents a variant of non-S-INDEL genotype having insertions and deletions in spike (S) genomic region. Croatia had been considered free of PED until 2016 when the first outbreak was reported in Osijek-Baranja County. In the present study we report molecular characterization of the first Croatian PEDV strain and following serological investigation of sows in eastern Croatia. Methods In April 2016 we received small intestines from two 8-10 days old diarrhoeic piglets. The holding of origin was located in Osijek-Baranja County and reported 20-30% mortality in suckling piglets. Initial diagnostics included detection of PEDV by two real-time RT-PCR protocols (N and S genome fragments) together with TGEV and RVA real-time RT-PCRs. NGS sequencing was performed on Illumina MiSeq platform and Sanger sequencing on conventionally amplified complete PEDV S gene (Geneious and MEGA7 software for data analysis). Serological investigation was carried out in 2017 on 266 sow sera collected from 39 holdings in Osijek-Baranja and Vukovar-Srijem Counties by commercial ELISA test (ID Screen® PEDV Indirect ELISA test ; IDVet, France). Results The presence of PEDV genome was confirmed by both real-time RT-PCR protocols (TGEV and RVA were excluded). NGS sequencing was rather unsuccessful as majority of virus related reads corresponded to bacteriophages and only four reads were PEDV related. However conventional RT-PCR and Sanger sequencing resulted in a complete S gene sequence sharing high identity with S-INDEL genotype strains from Germany, Austria, Slovenia, Italy and Romania. Serosurveillance resulted in three positive holdings (7.7%), located in both counties with 15.4% of positive sows. Seroprevalence within a positive holding went up to 82.8%. Conclusions PEDV has emerged in Croatian pig population causing moderate losses. Expectedly the circulating strain was a member of S-INDEL genotype. Serological surveillance revealed additional three holdings of the same enterprise that didn’t previously reported PED, demonstrating the importance of strict biosecurity measures.

PEDV ; phylogenetic analysis ; serological surveillance, emerging disease, Croatia

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