MOLECUAR AND PHYLOGENETIC CHARACTERIZATION OF INDIVIDUAL NEWCASTLE DISEASE VIRUSES DETECTED IN REPUBLIC OF MACEDONIA

Abstract

Main aim of this study was to identify and characterize NDV detected in Republic of Macedonia in the period from 2002-2012. Twenty-one strains of NDV detected in domestic poultry, pigeons and wild birds were examined. Identification of the strains was done with HIT of the classical methods and RT-qPCR and RT-PCR of the molecular methods. Virulence of the strains was determined with ICPI in the part of the strains and with determination of the amino acid motif of the cleavage site of the fusion gene by sequencing. Phylogenetic characterization of the strains was done with alignment with other strains from the region and with reference strains on a global level and with construction of phylogenetic trees. Of the total 21 strains, 12 strains belong to PPMV-1 and 9 were classical strains. All strains were virulent viruses. Representatives of the PPMV-1 belong to genotype VIb while classical strains belong to genotype VIId and are phylogenetically related to isolates from the region. Viruses detected in 2002-2003 are one of the first characterized representatives of the genotype VIId in the Southeast Europe. With a great degree of certainty it can be said that in the designated period there are at least two independent introductions of the viruses of genotype VIId, possibly even earlier, and a third introduction which occurred probably later i.e. in 2005. Two independent introductions of virulent viruses, one of which was previously present in the poultry were responsible for the epizootics of ND in 2005-2006. Permanent circulation of PPMV-1 was a documented threat to poultry. Diagnostic methods in accordance with OIE and EU legislative are successfully implemented in this study but national legislative should be revised in the context of definition of ND as per OIE and EU.