With increasing frequency, avian Metapneumovirus (aMPV) is reported to induce respiratory signs in chickens. An adequate knowledge of current aMPV prevalence among Italian broilers is lacking, with little information available on its economical and health impact on the poultry industry. In order to collect preliminary data on the epidemiological context of aMPV in broiler flocks, a survey was performed in areas of Northern Italy with high poultry density from 2014 to 2016. Upper respiratory tract swabs were collected and processed by A and B subtype-specific multiplex real-time reverse transcription PCR (RT-PCR). Samples were also screened for infectious bronchitis virus (IBV) by generic RT-PCR and sequencing. Productive data and respiratory signs were detailed where possible. The high prevalence of aMPV was confirmed in broilers older than 26 d and also attested in IBV-negative farms. All aMPV detections belonged to subtype B. Italian strain genetic variability was evaluated by the partial attachment (G) gene sequencing of selected strains and compared with contemporary turkey strains and previously published aMPV references, revealing no host specificity and the progressive evolution of this virus in Italy.

| Several viruses are associated with enteric diseases in avian species, causing decreased growth performance and mortality. In this study, 59 pools of intestinal content of layers, broilers, and breeders were investigated from different Brazilian regions for the presence of rotavirus (RVA, RVD, and RVF), avian coronavirus (ACoV), and avian astrovirus (AAstV), using PCR reactions followed by nucleotide sequencing and analysis. Twenty-nine pools (29/59; 49%) appeared positive for AAstV, 6 pools (6/59; 10%) were positive for RVD, forty-three pools (43/59; 72.8%) were positive for ACoV, and twenty-four pools (24/59; 40.67%) presented concomitant viral infections of two or three investigated agents. The relative high frequency of occurrence of the studied viruses both in single or concomitant infection emphasizes the need for continued monitoring of poultry flocks to better understand its epidemiology and understanding the impact of one virus on the pathobiology of second virus.

Ao meu orientador Prof. Dr. Paulo Eduardo Brandão que assumiu o desafio de desenvolver junto comigo um trabalho inovador. Agradeço a ele pelo apoio, pela paciência, pela ajuda, pelos conselhos e pela oportunidade de adquirir novos conhecimentos. A Laura Villarreal pelo carinho, amizade, confiança, conselhos, disposição, apoio incondicional e risadas ao longo deste caminho. Ao professor Leonardo José Richtzenhain pelo aprendizado e disponibilização do Laboratório de Virologia (VPS-USP) para a elaboração de parte deste trabalho. Aos demais professores do VPS. Aos funcionários do VPS e da FMVZ, especialmente a Danival Lopes "Dani", Maria Cristina Paick "Cris", Marcio, Isabela Furegatti e aos demais funcionários, pela amizade, convivência e ajuda. As técnicas Sheila Oliveira de Souza Silva e Sueli Taniwaki pelos conselhos, paciência, disposição e ajuda.

Chickens and quails samples were screened for IBV with an RT-PCR to the 3'UTR and positive samples were submitted to RT-PCRs to the RNA-dependent RNApolymerase gene (RdRp) and two different RT-PCRs to the spike gene, including a typing-multiplex one. Amplicons of 3'UTR (from quails samples) were cloned and sequenced. Two other RT-PCRs were used to detect the avian metapneumovirus (aMPV) and Newcastle disease virus (NDV). Avian coronavirus was found in all types of samples analyzed in chickens and quails raised on the same farms, aMPV subtype B was found in chickens and the NDV was not observed in any samples. All avian coronavirus found were classified as variants by multiplex RT-PCR, however, DNA sequences for gene S were not obtained. Based on the DNA sequences for genes encoding the protein RdRp and the 3'UTR region can be show that avian coronavirus in quails are closely related to avian infectious bronchitis virus, with a molecular phylogeographic diversity for quails viruses; thus, quails might act as reservoirs for avian coronaviroses when in close contact with other avian species.