A Brazilian field isolate (IBV/Brazil/PR05) of avian infectious bronchitis virus (IBV), associated with development of nephritis in chickens, was previously genotyped as IBV variant after S1 gene sequencing. The aim of this study was to evaluate the levels of IL-6 in kidneys and trachea of birds vaccinated and challenged with IBV/Brazil/PR05 strain, correlating these results with scores of microscopic lesions, specific IBV antigen detection and viral load. The up-regulation of IL-6 and the increased levels of viral load on renal and tracheal samples were significantly correlated with scores of microscopic lesions. Reduced levels of viral load were detected in kidneys of birds previously vaccinated and challenged, compared to non-vaccinated challenged group, although markedly microscopic lesions were observed for both groups. The expression of IL-6, present both in the kidney and in the tracheas, was dependent on the load of the virus present in the tissue, and the development of lesions was related with IL-6 present in the tissues. These data suggest that variant IBV/Brazil/PR05 can induce the expression of proinflammatory cytokines in a manner correlated with viral load and increased IL-6 is involved in the tissue with the influx of inflammatory cells and subsequent nephritis. This may contribute with a model to the development of immunosuppressive agents of IL-6 to prevent acute inflammatory processes against infection with IBV and perhaps other coronaviruses, as well as contribute to the understanding of the immunopathogenesis of IBV nephropatogenic strains.

Newcastle disease (ND) is caused by the avian paramyxovirus type 1 (APMV-1) or Newcastle disease virus (NDV) that comprises a diverse group of viruses with a single-stranded, negative-sense RNA genome. ND is one of the most important diseases of chickens, because it severely affects poultry production worldwide. In the 1970s, outbreaks of virulent ND were recorded in Brazil, and the strain APMV-1/Chicken/Brazil/SJM/75 (SJM) of NDV was isolated. This strain was characterized as highly pathogenic for chickens but not pathogenic for other bird species. Here we present the complete genome of NDV strain SJM and investigate the phylogenetic relationships of this virus with other NDV strains in terms of genome and proteins composition, as well as characterizing its evolution process. The NDV strain SJM is categorized as a velogenic virus and the complete genome is 15,192 nucleotides in length, consisting of six genes in the order 3'-NP-P-M-F-HN-L-5'. The presence of the major pathogenic determinant of NDV strains ((112)R-R-Q-K-R↓F(117)) was identified in the Fusion protein of the NDV strain SJM. In addition, phylogenetic analysis classified the NDV strain SJM as a member of class II, genotype V, and indicates that this virus help us in the understanding of the evolutionary process of strains belonging to this genotype. This study contributes to the growing interest involving the characterization of NDV isolates to improve our current understanding about the epidemiology, surveillance and evolution of the pathogenic strains.

A semi-nested reverse transcription-polymerase chain reaction (Semi-N-RT-PCR) was developed and used to detect the S glycoprotein gene of infectious bronchitis virus (IBV) strains and to discriminate H120 vaccine strain from other strains. Viral RNA was extracted from the allantoic fluid of chicken embryos and from tissues of chickens experimentally infected with different strains of IBV. Amplification and identification of the viral RNA was performed using two sets of primers complementary to a region of the S glycoprotein gene in the Semi-N-RT-PCR assay. The pair of primers used in the first PCR consisted of universal oligonucleotides flanking a more variable region of S1-S2 gene. The second primer pair was used in the Semi-N-RT-PCR and was comprised of one of the primers from the first universal pair together with either another universal internal oligolucleotide or a oligonucleotide sequence specific for the H120 strain of IBV. The universal primers detected all reference IBV strains and field isolates tested herein. The Semi-N-RT-PCR had high sensitivity and specificity, and was able to differentiate the H120 vaccine strain from other reference IBV strains; including M41 strain. All tissue samples collected from chickens experimentally infected with H120 or M41 strains were positive in the semi-nested RT-PCR using universal primers, while only the H120-infected tissue samples were amplified by the set of primers containing the H120-oligonucleotide. In conclusion, the ability of Semi-N-RT-PCR to detect distinct IBV strains and preliminarily discriminate the vaccine strain (H120) closes a diagnostic gap and offers the opportunity to use comprehensive PCR procedures for the IBV diagnosis

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