Infectious bronchitis (IB) casues multi-systemic infection in chickens with signs similar caused by other poultry pathogens and thus a high diagnostic accuracy can only be achieved by s series of laboratory assays. This article reviews in a brief way the traditional virus assays such as embryo innoculation, tracheal rings and virus neutralization assays for the direct detection of Avian infectious bronchitis virus (IBV) and methods based on gene molecular biology and some assays for the detection of anti-IBV antibodies, including ELISA. A critical view on each technique is also provived by the author.
Trachea, lung, and conjunctive samples from 51 commercial layer farms from Bastos region, São Paulo, Brazil, were submitted to nested-PCR and virus isolation in SPF chicken embryos for ILT diagnosis. This region experienced an outbreak characterized by respiratory signs, decrease in egg production and increased mortality. Out of the 51 tested field samples, 23 were positive for ILT by nested-PCR, 22 were positive after the virus isolation, and 24 were positive when both techniques were used. Newcastle disease virus, Avian pneumovirus, or Mycoplasma gallisepticum were not detected. Infectious bronchitis virus was detected in one farm and Mycoplasma synoviae was detected in eight farms. The high incidence of infectious laryngotracheitis virus (ILTV) detection, the high correlation between the observed clinical signs and the ILTV detection, and the results of differential diagnosis demonstrated that ILTV was the causative agent of the outbreak of respiratory disease observed in Bastos region, São Paulo, Brazil.
Rotaviruses have been identified as one of the main etiological agents of diarrhea and enteritis in mammals, including humans, and in avian species. Few studies have been published about enteric viruses in Brazilian poultry, including those related to rotavirus infection. Such studies demonstrate significant occurrence and the importance of enteric viruses in poultry presenting intestinal problems. Enteric viruses are the primary cause of injuries to the gut, allowing other agents, especially bacteria, to attach, to penetrate, and to replicate in the enteric tissue, leading to further damage. The aim of the present study was to detect rotavirus in the intestinal contents of layers and broilers by polyacrylamide gel electrophoresis (PAGE) and virus isolation in MA-104 cell culture. A total of 45.3% of all samples were positive to rotavirus; rotavirus frequencies were 48.7% in samples from flocks with diarrhea, 46.4% in flocks with delayed growth, and 30% in asymptomatic flocks. It was possible to isolate rotavirus in MA-104 cells from the nine rotavirus-positive randomly chosen samples. These results indicate that rotavirus may have an important role in pathogenesis of enteric disease.
This article reports a survey on turkey astrovirus (TAstV) and turkey coronavirus (TCoV) infections with RT-PCR in 17 turkey flocks affected by acute enteritis and two apparently normal turkey flocks located in the Southeastern region of Brazil by PCR (TAstV and TCoV). Seven out of the 17 affected flocks were positive for TAstV and 14 for TCoV, with seven co-infections. In one of the two apparently normal flocks, a TAstV-TCoV co-infection was found. Although a definitive association of these agents and the signs can not be made, the implications of these findings are discussed.
Avian Infectious Laryngotracheitis, caused by Infectious Laryngotracheitis Virus (ILTV), has been reported for decades in Brazilian laying and broiler flocks. More recently, outbreaks have occurred in São Paulo State. This study reports the application of PCR and DNA sequencing targeted to the p32 gene of ILTV using laying chicken samples from Bastos, São Paulo, Brazil. Three out of four field samples were positive by PCR. DNA sequencing of two samples evidenced homology of the amplified fragments with the p32 gene of ILTV. The results definitely confirmed the presence of ILTV in the birds during the outbreak. Further studies are needed to establish the sources of infection and to determine whether the detected virus was originated from vaccine or field virus strains.