Molecular diagnosis of Myxomavirus and characterization of strains detected in Italy during 2010 -

Myxomatosis, a lethal systemic disease of European rabbits (Oryctolagus cuniculus), is caused by Myxoma Virus (MV). The entire genome of the MV has been sequenced, allowing a systemic survey of the functions of a large number of putative pathogenic factors. The data present in literature have shown that myxoma virus is characterized by a high degree of genetic stability. Aim of this study was to identify molecular markers, on MV genome, for characterizing the isolates circulating in Italy during epidemiological studies. As a first step a PCR-based assay was established to rapidly diagnose the presence of myxoma virus in biological samples isolated from naturally infected rabbits. Twelve isolates collected during 2010-2011 from different Italian regions (wide ranging geographic locations), were then partially sequenced. Based on the sequence analysis we found nucleotides substitutions, deletions and insertions randomly present on the MV genome. We identified at least 6 different strains circulating in Italy during that time. In particular, one strain was identified in 5 samples (Cluster 1), another one in 3 samples (Cluster 2) and the remaining strains in single samples. Since three point mutations common to Cluster 1 can be identified with PCR-RFLPs analysis, these markers could be easily used to perform epidemiologic studies. Interestingly, one strain from Sicily region (South Italy) has shown 100% nt identity with the Borghi vaccine strain, with a region of the genome suggesting a possible in vivo recombination between a circulating wild virus and a Borghi vaccine strain.