Detection of variant infectious bronchitis viruses in Sri Lanka (2012-2015)

Dried Blood Spots technology for veterinary applications and biological investigations: technical aspects, retrospective analysis, ongoing status and future perspectives

Dried Blood Spots (DBS) technology has become a valuable tool in medical studies, however, in veterinary and biological research DBS technology applications are still limited. Up-to-date no review has comprehensively integrated all the evidence existing across the fields, technologies and animal species. In this paper we summarize the current applications of DBS technology in the mentioned areas, and provide a scope of different types of dried sample carriers (cellulose and non-cellulose), sampling devices, applicable methods for analyte extraction and detection. Mammals, birds, insects and other species are represented as the study objects. Besides the blood, the review considers a variety of specimens, such as milk, saliva, tissue samples and others. The main applications of dried samples highlighted in the review include epidemiological surveys and monitoring for infections agents or specific antibodies for disease/vaccination control in households and wildlife. Besides the genetic investigations, the paper describes detection of environmental contaminants, pregnancy diagnosis and many other useful applications of animal dried samples. The paper also analyses dried sample stability and storage conditions for antibodies, viruses and other substances. Finally, recent developments and future research for DBS technology in veterinary medicine and biological sciences are discussed.

Co-circulation of genetically diverse population of vaccine related and unrelated respiratory mycoplasmas and viruses in UK poultry flocks with health or production problems

Respiratory diseases continue to have a major impact on poultry health, welfare and productivity. However, little information is available on their current status in UK poultry flocks. We investigated the presence of four economically important respiratory pathogens in healthy or problematic flocks; infectious bronchitis virus (IBV), avian metapneumovirus (aMPV), Mycoplasma gallisepticum (Mg) and Mycoplasma synoviae (Ms). Samples from 131 UK poultry flocks were received during the 12 month study period. Oropharyngeal (OP) swabs were taken from eight birds per flock and accompanied with flock health information. The study included 118 chicken, 6 pheasant and 5 turkey flocks, and 1 quail and 1 partridge flock. Chicken flocks were of layers (n = 98), broilers (n = 15), breeders (n = 3) and undisclosed (n = 2). Flock ages ranged from 3 to 72 weeks old, and the average flock size was 17,633 birds. PCR detected 65 (49.6%), 59 (45%) and 8 (6.1%) flocks as positive for IBV, Mg/Ms and aMPV respectively. Analysis of the mgc2 gene of the Mg isolates revealed high similarities to Mg TS-11 and Mg 6/85. Further gene analysis found that the TS-11-like isolates were unrelated to the TS-11 vaccine. Multi-locus sequence typing (MLST) analysis identified the majority of positive Ms as ST21, along with ST2 (MS-H-like), ST6 and ST43. IBV S1 gene sequencing identified strains as 793B (66.7%), Arkansas (23.8%) and Massachusetts (9.5%). All aMPV positive samples belonged to subtype B. Findings indicate that over half of the flocks sampled were positive for at least one of the four vaccine or field strains of mycoplasmas or viruses.

Evaluation of full S1 gene sequencing of classical and variant infectious bronchitis viruses extracted from allantoic fluid and FTA cards

Sequence variability in the S1 gene determines the genotype of infectious bronchitis virus (IBV) strains. A single RT-PCR assay was developed to amplify and sequence the full S1 gene for six classical and variant IBVs (M41, D274, 793B, IS/885/00, IS/1494/06 and Q1) enriched in allantoic fluid (AF) or the same AF inoculated onto Flinders Technology Association (FTA) cards. Representative strains from each genotype were grown in specific-pathogen-free eggs and RNA was extracted from AF. Full S1 gene amplification was achieved using primer A and primer 22.51. Products were sequenced using primers A, 1050+, 1380+ and SX3+ to obtain short sequences covering the full gene. Following serial dilutions of AF, detection limits of the partial assay were higher than those of the full S1 gene. Partial S1 sequences exhibited higher-than-average nucleotide similarity percentages (79%; 352 bp) compared to full S1 sequences (77%; 1756 bp), suggesting that full S1 analysis allows greater strain differentiation. For IBV detection from AF-inoculated FTA cards, four serotypes were incubated for up to 21 days at three temperatures, 4°C, room temperature (approximately 24°C) and 40°C. RNA was extracted and tested with partial and full S1 protocols. Through partial sequencing, all IBVs were successfully detected at all sampling points and storage temperatures. In contrast, using full S1 sequencing it was not possible to amplify the gene beyond 14 days or when stored at 40°C. Data presented show that for full S1 sequencing, a substantial amount of RNA is needed. Field samples collected onto FTA cards are unlikely to yield such quantity or quality.

ABBREVIATIONS

AF: allantoic fluid; CD50: ciliostatic dose 50; FTA: Flinders Technology Association; IB: infectious bronchitis; IBV: infectious bronchitis virus.