Giulia Rossi

Rapid detection of subtype B avian metapneumoviruses using RT-PCR restriction endonuclease digestion indicates field circulation of vaccine-derived viruses in older turkeys

Live vaccines predominantly control avian metapneumovirus (aMPV) infection in poultry flocks, but vaccine virus can be found for extended periods after application. The most frequently used aMPV vaccine in Italy, VCO3 subtype B, was shown to contain a unique Tru9I restriction endonuclease site within the amplicons produced by a commonly used aMPV diagnostic reverse transcriptase (RT)-nested polymerase chain reaction (PCR). Analysis of European and database logged subtype B aMPV sequences confirmed that the sequence occurred only in the VC03 vaccine. A subsequent RT-PCR restriction endonuclease study of field samples, collected from turkeys between 2007 and 2012, detected subtype B vaccine-derived strains in 12 of 90 samples tested that were collected from birds under 12 weeks of age.

A molecular epidemiology study based on VP2 gene sequences reveals that a new genotype of infectious bursal disease virus is dominantly prevalent in Italy

ABSTRACT A distinctive infectious bursal disease (IBD) virus genotype (ITA) was detected in IBD-live vaccinated broilers in Italy without clinical signs of IBD. It was isolated in specific-pathogen-free eggs and molecularly characterized in the hypervariable region of the virus protein (VP) 2. Phylogenetic analysis showed that ITA strains clustered separately from other homologous reference sequences of IBDVs, either classical or very virulent, retrieved from GenBank or previously reported in Italy, and from vaccine strains. The new genotype shows peculiar molecular characteristics in key positions of the VP2 hypervariable region, which affect charged or potentially glycosylated amino acids virtually associated with important changes in virus properties. Characterization of 41 IBDV strains detected in Italy between 2013 and 2014 showed that ITA is emergent in densely populated poultry areas of Italy, being 68% of the IBDV detections made during routine diagnostic activity over a two-year period, in spite of the immunity induced by large-scale vaccination. Four very virulent strains (DV86) and one classical strain (HPR2), together with eight vaccine strains, were also detected. The currently available epidemiological and clinical data do not allow the degree of pathogenicity of the ITA genotype to be defined. Only in vivo experimental pathogenicity studies conducted in secure isolation conditions, through the evaluation of clinical signs and macro/microscopic lesions, will clarify conclusively the virulence of the new Italian genotype.

Characterization and antimicrobial resistance analysis of avian pathogenic Escherichia coli isolated from Italian turkey flocks

This study investigated the occurrence of avian pathogenic Escherichia coli (APEC) in a finishing turkey commercial farm, carrying out longitudinal surveys involving 3 consecutive flocks. The diversity and the distribution of the E. coli strains detected during colisepticemia outbreaks were examined. The strains were isolated, serogrouped, assessed for the presence of virulence-associated genes, typed by random amplification of polymorphic DNA (RAPD), and antimicrobial resistance analysis was then carried out. Escherichia coli O78 and O2 were predominantly found. Moreover, based on the somatic antigens used in the study, strains were recovered that were nontypeable. On one occasion, an E. coli O111 strain was found in turkeys. The E. coli isolates differed in terms of antibiotic resistance and RAPD profile. All strains possessed the virulence genes that enabled them to be considered APEC. Strains not only differed between flocks, but also within the same flock. These findings point out the importance of addressing colibacillosis therapy on the basis of a sensitivity test.

In vitro evaluation of live attenuated vaccines against Salmonella enteritidis: cell-mediated immune response

Abstract The use of Salmonella enteritidis (SE) live attenuated vaccines is one of the major tool to reduce this infection in commercial poultry. In this work, techniques, evaluating the presence and the expression of some cytokines, were studied to improve the knowledge of the cellular-mediated immune response following SE vaccination. This study demonstrated that SE vaccination enhances the production of INF-γ, IL-8, iNOs, while downregulates IL-1β. Between these immunologic parameters, the evaluation of INF-γ seems to be the most significant and easy test to plan and optimize SE vaccination programs.

In vitro evaluation of live attenuated vaccines against Salmonella enteritidis: humoral immune response

Abstract Salmonella enteritidis (SE) vaccination is one of the major tool to reduce the infection in commercial poultry. In this work, techniques, evaluating the presence of Ig-G and Ig-A in serum, tears and intestinal secretions, were studied to improve the knowledge of the humoral immune response following SE live attenuated vaccination. The Ig-G and Ig-A ELISA are important and easy tests to plan and optimize SE vaccination programs.