Isolation and molecular characterization of nephropathic infectious bronchitis virus isolates of Gujarat state, India

Avian infectious bronchitis virus (AIBV) review by continent

Infectious bronchitis virus (IBV) is a positive-sense, single-stranded, enveloped RNA virus responsible for substantial economic losses to the poultry industry worldwide by causing a highly contagious respiratory disease. The virus can spread quickly through contact, contaminated equipment, aerosols, and personal-to-person contact. We highlight the prevalence and geographic distribution of all nine genotypes, as well as the relevant symptoms and economic impact, by extensively analyzing the current literature. Moreover, phylogenetic analysis was performed using Molecular Evolutionary Genetics Analysis (MEGA-6), which provided insights into the global molecular diversity and evolution of IBV strains. This review highlights that IBV genotype I (GI) is prevalent worldwide because sporadic cases have been found on many continents. Conversely, GII was identified as a European strain that subsequently dispersed throughout Europe and South America. GIII and GV are predominant in Australia, with very few reports from Asia. GIV, GVIII, and GIX originate from North America. GIV was found to circulate in Asia, and GVII was identified in Europe and China. Geographically, the GVI-1 lineage is thought to be restricted to Asia. This review highlights that IBV still often arises in commercial chicken flocks despite immunization and biosecurity measures because of the ongoing introduction of novel IBV variants and inadequate cross-protection provided by the presently available vaccines. Consequently, IB consistently jeopardizes the ability of the poultry industry to grow and prosper. Identifying these domains will aid in discerning the pathogenicity and prevalence of IBV genotypes, potentially enhancing disease prevention and management tactics.

Pathology, tissue tropism and antibody response of nephropathogenic infectious bronchitis virus (IBV) Indian isolate in experimentally infected chicken

Infectious bronchitis virus isolate (IND/AHL/16/01) from a disease outbreak characterized by nephritis, gout and mortality in coloured layer pureline at Directorate of Poultry Research, India was characterized as nephropathogenic strain by S1 genotyping and phylogenetic analysis. Serotyping with homologous and heterologous serum (M41) by virus neutralization assay in embryonated chicken eggs (ECE) showed indices of 7.3 and 2.3 respectively. Pathogenesis, tissue tropism and host immune response induced by this isolate were investigated in experimentally infected chicken. A total of 150, twenty days old seronegative Vanaraja birds were inoculated through intranasal and intravenous route using 10^4.7 Embryo infective dose₅₀ (EID₅₀/ml). Infected chickens were sacrificed at 4 h, 1, 2, 3, 5, 7, 11, 13, 15- and 20-days post-infection (dpi) for necropsy. Tissues were collected for histopathology and virus detection by isolation in ECE and by reverse transcription- PCR (RT-PCR). Serum was also collected at these intervals to investigate the specific antibody response induced. The symptoms started as early as 3 dpi and included primarily wet droppings, diarrhoea, dehydration rather than respiratory symptoms. Gross lesions were prominent in kidneys including mottling and congestion. Virus isolation and RT-PCR detection indicated the presence of virus as early as 4 h post-infection in trachea and 24 h in kidney and lungs and from 2 dpi in caecal tonsil. The host antibody response after experimental infection in serum by ELISA indicated that the protective titres were induced from 13 dpi and peaked at 35 dpi and declined thereafter. Overall, this isolate is nephropathogenic and capable of inducing severe nephritis and production loss in broilers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13337-021-00693-4.

A bio-safe multiple antigenic peptide (MAP) enzyme-linked immunoassay for the detection of antibodies to infectious bronchitis virus in chickens

The objective of the study was to develop a bio-safe synthetic peptide ELISA for the detection of antibodies against the infectious bronchitis virus (IBV) using a novel multiple antigenic peptide approach (MAP). After initial ELISA optimization, diagnostic sensitivity (DSn) and specificity (DSp) for the linear peptides were determined using receiver operator curve (ROC) analysis. The peptide IBVP1 showed 90.44% DSn and 88.64% DSp at ROC cut off 22.8% while IBVP2 showed 88.24% DSn and 85.23% DSp at ROC cut off 23.05%. The multimerization of linear peptides to MAP design resulted in the improvement of the diagnostic efficiency up to 94.85% DSn and 92.05% DSp for IBVM1 with 19.95% cut off. A similar improvement in the performance was also observed with 92.65% DSn and 90.91% DSp for IBVM2 at 20.72% cut off. All the peptides were tested for diagnostic specificity and did not show the cross-reactivity with Newcastle disease virus and infectious bursal disease virus positive serum samples. In addition, repeatability testing for all linear and multimeric peptide showed that the coefficient of variation for intra-assay was within the expected limits, ranging from 2.4 to 10.4% and inter-assay coefficient of variation was ranging from 5.56 to 14.3%. In a nutshell, the present study used predicted B cell epitope, the synthetic peptide in linear and multimeric design for IBV antibody detection. The study also highlights peptide antigen with modified scaffold design could be a safe alternative to whole virion-based ELISA for IBV antibody detection.

Emergence of variant avian infectious bronchitis virus in India

BACKGROUND

Infectious bronchitis virus (IBV) is the etiological agent of an acute and highly contagious disease. Infectious bronchitis (IB) affects chicken of all ages and poses major economic loses to the poultry industry worldwide. The continuous evolution of the spike protein (S1) of IBV is responsible for the prevalence of many serotypes/genotypes around the world. Multiple lineages of IBV strains have been detected in chicken flocks in India since 2003.

AIMS

To detect IBV genotypes prevalent in India.

METHODS

Organ samples from 20 IBV-positive flocks with variable clinical signs were used for the amplification of the S1 gene of IBV by reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

Positive PCR amplicons were sequenced. Sequence analysis showed that 14 field isolates belonged to the GI-1 genetic lineage (Mass 41 serotype), two field isolates belonged to the GI-13 (UK 4/91 variant IBV strain), one field isolate grouped with GIII, GV, and GVI genetic lineage and three belonged to a variant genotype unique to India (GI-24). Phylogenetic analysis also showed a similar type of grouping within the field isolates. Among the fourteen GI-1 isolates, 12 were isolated between 2003 and 2006 and only two were isolated between 2009 and 2011. The two field isolates belonging to GI-13 were isolated in 2007, another one belonging to GIII, GV, and GVI was isolated in 2010 and three field isolates were not close to any reference IBV sequences isolated in 2006 (IND-TN-168-06), 2010 (IND-TN-280-10) and 2011 (IND-TN-290-11).

CONCLUSION

A unique variant of IBV is emerging in India (GI-24). Our findings will have important implications for future vaccine intervention.

Avian Infectious Bronchitis Virus

Avian infectious bronchitis (IB) is caused by avian infectious bronchitis virus (IBV) belonging to Coronaviridae family. The disease is prevalent in all countries with almost 100% incidence rate. Chicken and commercially reared pheasant are the natural host for IBV. Virus causes respiratory diseases, poor weight gain, feed efficiency in broiler, damage to oviduct, and abnormal egg production in mature hens resulting in economic losses. IBV also replicates in tracheal and renal epithelial cells leading to prominent tracheal and kidney lesions. Virus undergoes spontaneous mutation leading to continual emergence of new variants. The effectiveness of immunization program is diminished because of poor cross-protection among the serotypes. Identification of circulating serotypes is important in controlling IBV infection. Toll-like receptor 3 (TLR3) and TLR21 are involved in early recognition of virus resulting in induction of inflammatory cytokines. Both humoral and cellular immune responses are important in the control of infection. Humoral immunity plays an important role in recovery and clearance of viral infection. IBV-specific cytotoxic T lymphocytes induce lysis of IBV-infected cells. Effective diagnostic tools are required at field level to identify different IBV variants. Embryonated chicken eggs are effective model for virus isolation. Identification by other specific methods like virus neutralization (VN), hemagglutination inhibition (HI), enzyme linked immunosorbent assay (ELISA), immunohistochemistry, or nucleic acid analysis or by electron microscopy is also indispensable. VN test in tracheal organ culture is the best method for antigenic typing for surveillance purposes. Continuous epidemiological surveillance, strict biosecurity measures, and vaccine effective against various serotypes are necessary for controlling IB in chickens.

Emergence of a genotype I variant of avian infectious bronchitis virus from Northern part of India

Infectious bronchitis virus (IBV) is one of the foremost causes of a persistent economic burden to poultry industries worldwide. IBV belongs to the genus Gammacoronavirus within the family Coronaviridae. The IBV infection leads to respiratory and nephrogenic symptoms in broiler chickens. In addition, its infection leads to reduced fertility and hatchability in layer birds. We determined the first complete genome sequence of a variant IBV from an outbreak in Haryana state of the Northern part of India using next generation sequencing. On phylogenetic analysis of the IBV isolate, it clustered with genotype I lineage 1 (GI-1). The deduced amino acid sequence of S gene of IBV isolates showed a high level of identity with strains isolated from Tamil Nadu and the reference vaccine strains. Our result suggests that the IBV virus isolated from unvaccinated chicken flocks in North India might be a revertant strain originally evolved from the live attenuated vaccine strains used in the region. Determination of the complete genome sequence of additional IBV isolates from India is necessary to understand the epidemiology of IBV in India.

Infectious Bronchitis Virus Variants: Molecular Analysis and Pathogenicity Investigation

Infectious bronchitis virus (IBV) variants constantly emerge and pose economic threats to poultry farms worldwide. Numerous studies on the molecular and pathogenic characterization of IBV variants have been performed between 2007 and 2017, which we have reviewed herein. We noted that viral genetic mutations and recombination events commonly gave rise to distinct IBV genotypes, serotypes and pathotypes. In addition to characterizing the S1 genes, full viral genomic sequencing, comprehensive antigenicity, and pathogenicity studies on emerging variants have advanced our understanding of IBV infections, which is valuable for developing countermeasures against IBV field outbreaks. This review of IBV variants provides practical value for understanding their phylogenetic relationships and epidemiology from both regional and worldwide viewpoints.

Phylogenetic and antigenic analysis of avian infectious bronchitis virus in southwestern China, 2012-2016

The aim of this study was to decipher the molecular epidemiological and antigenic characteristics of infectious bronchitis virus strains (IBVs) isolated in recent years in southwestern China. A total of 24 field strains were isolated from diseased chickens between 2012 and 2016. Phylogenetic analysis based on S1 nucleotide sequences showed that 16 of the 24 isolates were clustered into four distinct genotypes: QX (37.5%), TW (16.7%, TWI and TWII), Mass (8.3%), and J2 (4.2%). The QX genotype was still the prevalent genotype in southwestern China. Recombination analysis of the S1 subunit gene showed that eight of the 24 field strains were recombinant variants that originated from field strains and vaccine strains. A new potential recombination hotspot [ATTTT(T/A)] was identified, implying that recombination events may become more and more common. The antigenicity of ten IBVs, including seven field strains and commonly used vaccine strains, were assayed with a viral cross-neutralization assay in chicken embryonated kidney cells (CEK). The results showed that the ten IBVs could be divided into four serotypes (Massachusetts, 793B, Sczy3, and SCYB). Sczy3 and 793B were the predominant serotypes. Six of the seven field isolates (all except for cK/CH/SCYB/140913) cross-reacted well with anti-sera against other field strains. In conclusion, the genetic and antigenic features of IBVs from southwestern China in recent years have changed when compared to the previous reports. The results could provide a reference for vaccine development and the prevention of infectious bronchitis in southwestern China.

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The QX genotype was still the prevalent genotype in southwestern China, 2012–2016.

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The Sczy3 and 793B were the predominant serotypes in analyzed IBVs.

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A new potential recombination hotspot [ATTTT(T/A)] in S1 gene was identified.