Full-length genomes molecular investigation of Infectious Bronchitis Virus strains

Infectious Bronchitis virus (IBV) is one of the most important pathogen for poultry, and is ubiquitous in most parts of the world. Despite the advances in sequencing techniques, a wide collection of full-length sequences and a comprehensive understanding of the mutation affecting IBV virulence are still lacking. In the first part of the project, we obtained and analyzed the complete sequence of a Q1 strain isolated in Italy in 2013 in order to have more information on the genetic characteristics and the origin of this strain. The results of this study led to the hypothesis that the Q1 genotype was genetically related to the genotype 624I circulating in Italy from the 1960s. The full-length analysis of a 624I IBV strain isolated in Italy in 1996 was carried out in order to find out genetic correlations between Q1 and 624I genotypes. Results strongly suggest that 624I genotype has played an important role in the emerge and evolution of Q1 genotype. Findings support the hypothesis that elects 624I genotype as Q1 ancestor and suggest that 624I genotype was introduced in China somewhere in the past, there evolved into Q1 genotype, before its reintroduction in Italy. In the second part of the project the complete genome sequences of a QX genotype vaccine and its progenitor strain were obtained and analyzed in order to determine vaccines markers, thereby enabling detection on farms and to investigate the changes occurred during the attenuation process.