Avian metapneumovirus: susceptibility at different cell lines and production of monocioinal antibodies

Author(s)

Lia Treptow Coswig

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2008-10-07

Examining board members

Clarice Weis Arns; Flávia Saldanha Kubrusly; Liana Maria Cardoso Verinaud; Cleide Aschenbrenner Consales; Isabela Cristina Simoni

• Advisor: Dagmar Ruth Stach Machado; Clarice Weis Arns

Abstract

Avian Metapneumovirus (AM PV) , also denominated virus of the rhinotracheitis of the turkeys, it is a virus that attacks and it causes infection in the upper respirator) tract of chickens and turkeys. Besides the respiratory infection, in breeders and layers is associated with a significant fall in the production of eggs. In chickens the virus is related with the Swollen Head Syndrome (SHS), an illness multifactorial and for this reason it is very important the differential diagnosis. Tests accomplished with monoclonal antibodies (Mabs) and molecular techniques are capable to detect differences among the subtypes of the virus. Methods for the diagnosis of AMPV infections include detection or isolation of the virus itself, demonstration of a specific antibody response to the virus. For the primary isolation of the two samples of AMPV SHS-BR-121 (subtype A) and STG-SHS-1439 (subtype B) was it accomplished ir chicken embryo tracheal" organ culture (TOC), in chicken embryo fibroblast cell culture (CEF) and was it accomplished in cell line chicken embryo related (CER). Done the comparison of the averages of the titers obtain for the two strains, in cellline CER, did present statistically significant difference (P=0,014) with p< 0,05. The growth of SHS121-BR and STG-SHS-1439 was evaluated in six different celllines (CER, Vero, BHK21, HEp-2, MDBK and ED). CER, Vero and BHK-21 showed to be the most appropriate for virus multiplication. The titers in these cells varied from 105.5 to 107,o/mL !CID50, for the virus SHS-BR-121, and 105,5 to 106,o/mL TCID50 for the virus STG-SHS71439. The differences among the averages of the titers in the different cell lines was statistically significant differences (P=0,01) with p<0,05 for the strain SHS-BR-121 in CER cellline. One-step growth curves of the strains SHS-BR-121 and STG-SHS-1439 in CER, Vero and BHK-21 showed that there was not statistically significant difference in the infectious virus titers from 0 to 60 hours after infection. Five monoclonal antibodies were obtained for the viral antigen through the cell fusion that showed the isotypes IgG1, IgG2a and IgG2b, when of the characterization of Mabs. Three of them showed neutralizing activity and four inhibited the fusion in vitro. These MAbs were used to investigate antigenic relationship among three strains (SHS-BR-121, STG 854/8o/and TRT1439/91) of a MPV subtypes A and B using cross-neutralization test. When the five hybridomas were analyzed showed result positive for the homologus virus. In relation t4 two samples of heterologus AMPV three Mabs were positive to heterologus AMPV. Th4 results confirm that the two monoclonal antibodies described can be used as a valuable tool in the epizootiological and serological studies, and also for the specific diagnosis o the subtypes in the infection for Avian Metapneumovirus (AU)