Tracheal organ cultures (TOC) were prepared and used for evaluating four Brazilian isolates of infectious bronchitis virus (IBV). IBV field isolates and vaccine strains were titrated in TOC and results compared to those from chicken embrionated eggs. Serum neutralization (SN) employing IBV strain-specific serum was performed for evaluating relationships between isolates. Titration results of tests performed in TOC or eggs were in mutual agreement and were considered for validating the adapted TOC methodology as alternative for virological studies in our laboratory. Sera specific to M41 (Massachusetts) or A5968 (Connecticut) did neutralize their respective IBV strains only. Field strains 208 and 29-78 specific sera did neutralize Massachusetts serotype strains M41 and H120, but PM2 serum did only M41. Strain PM4 specific serum did not neutralize any of the reference IBV analyzed, including M41, A5968 and H120 and may indicate that the isolate is serologically different from the Massachusetts serotype, currently adopted for vaccine strains in Brazil.

Um painel de anticorpos monoclonais (AcM) específicos contra o vírus da bronquite infecciosa das galinhas (VBIG) amostra Massachusetts M41 foi desenvolvido com a finalidade de possibilitar ferramentas para futuros estudos de amostras locais de VBIG. Os clones produtores de AcM foram detectados e caracterizados por ELISA, e para a determinação quanto à especificidade ao componente de VBIG foi utilizado western blotting (WB). Os híbridos produtivos foram clonados por diluição limitante, expandidos in vitro e mantidos em nitrogênio líquido. As bandas protéicas reconhecidas em WB pelos AcM apresentaram pesos moleculares que variaram de 180 a 30 kDa. Oito AcM reconheceram apenas um polipeptídeo e quatro ligaram-se ao polipeptídeo S (3, 18, 52 e 57) inteiro, com a banda de peso molecular aproximado de 180 kDa. Cinco AcM (5, 12, 41, 70 e 72) ligaram-se em mais de uma banda de VBIG. Outros sete AcM não se ligaram a nenhum polipeptídeo de VBIG. Entre os AcM que apresentam perspectivas de utilização em pesquisa e diagnóstico de VBIG incluem-se os produzidos pelo clone 42, dirigido contra S1, os produzidos pelos clones 34, 43 e 71, dirigidos contra S2, pelos clones 7 e 22, dirigidos contra M e pelos clones 15 e 50, cujos AcM reagiram contra a nucleoproteína N.

Monoclonal antibodies (Mab) specific to IBV Massachusetts M41 were produced aiming to the development of assays for IBV diagnosis and research, such as for rapidly detecting or typing IBV isolates. Mabs were detected by ELISA and characterized based on the isotype (ELISA) or IBV structural specificity (western blotting) respectively as IgA, IgG1, IgG2a, IgG2b or IgM or as specific to S1 (42), S2 (34, 43 and 71), M (7 and 22), N (15 and 50) and S whole molecule (3, 18, 52 and 57), the major IBV structural proteins