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Section B: Mycoplasma synoviae (MS) is a poultry pathogen related to severe economic losses in all the productive sectors. A live MS vaccine (MS-H) obtained by mutagenizing an Australian field strain has recently been introduced in Italy. The aim of the present study is to evaluate the vaccine behavior in a broiler breeder group vaccinated with MS-H and the efficacy of the available laboratory tests in properly identifying its presence. Several laboratory tests (serology, PCR, cultivation and genotyping techniques) were applied in breeders and their progeny (serology, biomolecular techniques) at different times during the trial. The vaccine showed a great diffusion in the population, proved by the wide serological response and the positivity in PCR,moreover at the end of the trial (55 weeks after vacination) the MS cultivation was successfully applied. No signs of vertical transmission were evidenced. The analysis of different genes was found to be necessary in order to clearly classify all the positive samples. The application of different serological and biomolecular methods could be useful to monitor vaccinated avian flocks, moreover the development specific discriminating tests (DIVA) should be encouraged, as well as genotyping techniques to study the MS population circulating in HDPPAs. Section A: Avian Metapneumovirus (aMPV) is a respiratory pathogen causing the Turkey Rhinotracheitis (TRT). It is associated to the Swollen Head Syndrome in broilers, but its role as primary respiratory pathogen in this species is nowadays not completely defined. Mycoplasma synoviae (MS) is a respiratory bacterial pathogen whose importance increased in the last few years. The greater relevance of aMPV and MS in the poultry sector and the lack of experimental studies regarding their co-infection in broilers led to this infection model. The experimental design was based on 4 experimental groups (A-aMPV, B-aMPV+MS, C-MS, D-negative control), field isolates were used for both the pathogens’ inocula which were performed through the oculo-nasal route. At scheduled times during the trial, which lasted 35 days, 5 animal/group were euthanized for further investigations (serology, gross pathology, biomolecular techniques) and during the whole period of time animals were monitored for clinical observations. Aim of the present study was: reproducing the aMPV and aMPV+MS infection in broilers, evaluating the diffusion of these pathogens in the host and the possibility of a synergistic interaction between them. First of all, there was evidence of respiratory disease in group A (aMPV), in which signs of SHS were expressed; moreover the way of introduction of MS (eye and nostril) resulted effective in reproducing the disease, confirming the possible application of this type of infection for experimental purposes. The clinical and laboratory investigations suggests the possible synergic interaction between aMPV and MS in the nasal turbinates (group B, aMPV+MS), suggesting the possible contribute of MS in developing SHS. On the other hand, the possible addictive/synergistic interaction was not detected in any other respiratory tissue. The present results evidence the possible role of aMPV in leading the way for MS to peripheral and non-typically target tissues. Further studies could be useful to better understand the nature of the interaction between the two pathogens in different tissues and to evaluate, basing on the economic impact and epidemiological context, the possible application of control measures. |
