IDENTIFICATION AND MOLECULAR CHARACTERIZATION OF ATYPICAL PORCINE PESTIVIRUS (APPV) IN CENTRAL ITALY.
A novel atypical porcine pestivirus (APPV), firstly discovered in USA in 2015 and now called Pestivirus K, was subsequently reported in Europe and Asia, both in pigs and in wild boars, sometimes associated with congenital tremor (CT) clinical signs in piglets. In this study, a virological survey was performed in central Italy to investigate the presence of APPV genome. One APPV strain was detected by Real Time RT-PCR and named APPV-LA/4911/2016. It comes from an adult and asintomatic pig, living in a breeding herd from Lazio region, without any anamnestic CT history. Sequences from NS5B and NS3 genomic regions were submitted to phylogenetic analysis. APPV-LA/4911/2016 clustered together with the corresponding NS5B and NS3 fragments of some German APPV strains and showed the highest similarity with APPV strains from Hungary. In addition, it is very genetically divergent from Chinese APPV strains. These data confirm the high APPV genetic diversity, not being able to cluster this virus according to the geographic area. Of course, APPV-LA/4911/2016 is similar to some Italian strains, already identified, for NS3 region. These results showed that APPV has been circulating in Italy at least since 2016 and it has been involved in a probable multiple introduction in our country. The animal and swine products trade movements and the global pig transport could have allowed the spread of APPV in different countries of three continents, as well as the introduction of APPV in Italy. Therefore, APPV presence in asintomatic pigs could be assignated mainly to its capability to induce a persistent infection, required for disease manteinance and spread. In the same time, APPV could be a door opener virus, like the most of Pestivirus, in case of co-infections with other swine pathogen agents. Further investigation should be performed to evaluate origin, epidemiological distribution, molecular evolution and pathogenetical role of this emerging swine virus.