Fifteen isolations of infectious bronchitis (IB) virus were made from a total of 126 Brazilian poultry flocks of all ages that were examined. These flocks (14 chicken and 1 quail) were experiencing a variety of IB-like conditions including respiratory disease, digestive and kidney problems, and drops in egg production. One of the isolates was of the Massachusetts serotype. The remainder were examined by means of cross-neutralization tests in tracheal organ cultures and were shown to belong to at least four antigenic groups, all different from ones described previously in other countries. Some, but not all, of the flocks from which they were isolated had been vaccinated against IB with vaccines of the Massachusetts serotype. In vivo protection studies showed that the MA5 vaccine (of the Massachusetts serotype) protected well against challenge with four of these isolates, representing the different serotypes reported in this study.

The aim of this study was to improve a reverse transcriptase (RT)-nested-polymerase chain reaction (PCR) able to differentiate avian pneumovirus (APV) subtypes A and B, and to characterize new Brazilian isolates. Representative APV strains and clinical field samples from chickens and turkey flocks were amplified in the chicken embryo-related cell line. Viral RNA was extracted from harvested cells, and submitted to cDNA synthesis. The primers utilized for RT-PCR were compatible with the G gene of both the A and B subtypes of APV, while the nested primers were subtype specific. This approach showed that three new APVs from chickens and one from turkeys were subtype A, confirmed by sequencing. This is the first report of APV isolation from turkeys in Brazil. Four other APVs were detected and classified as subtype A by RT-nested-PCR. These optimized techniques could be useful for differentiation of APV subtypes A and B, proving to be a valuable molecular epidemiological tool.

Este trabalho descreve un surto de Doença Infecciosa Bursal (DIB) ocorrendo em frangos de corte oriundos de reprodutoras imunizadas, alojadas em quatro granjas vizinhas e vacinadas ou nio vacinadas com vírus da DIB. Mortalidade elevada, mau desempenho e ocorrência de infecções múltiplas foram os principais achados de campo. A DIB foi reproduzida experimentalmente em galinhas SPF e comerciais através de inoculaçBo do homogenato de Bursa de Fabricius. Anticorpos contra vírus da DIB e partículas virais (33 a 38 nm) foram detectadas nas aves experimentalmenteinoculadas.