Characterization of Nephropathogenic Infectious Bronchitis Virus DMV/1639/11 Recovered from Delmarva Broiler Chickens in 2011

Abstract

A limited outbreak of nephropathogenic infectious bronchitis (NIB) occurred in three Delmarva (DMV) commercial broiler chicken flocks in 2011. Isolates of NIB virus (NIBV)--DMV/1639/11, DMV/3432/11, and DMV/3902/11--were characterized by sequence analysis of the N-terminal subunit (S1) of the spike (S) gene. Findings indicated that the isolates were identical to each other and to PA/9579A/10, a 2010 isolate from poultry in Pennsylvania. The 2010 and 2011 isolates appear to have originated from a 1997-2000 NIB outbreak in Pennsylvania. DMV/1639/11 and PA/9579A/10 were determined to be nephropathogenic in susceptible chickens, yielding virus reisolations from kidney and inducing characteristic interstitial nephritis microscopic lesions. In a controlled laboratory study, 40% of chickens vaccinated with a combination live vaccine containing infectious bronchitis virus (IBV) strains Massachusetts (Mass) + Connecticut (Conn) were positive on virus isolation attempts after challenge with DMV/1639/11, compared with only 13% of Mass + Arkansas (Ark) vaccinates. Both combination vaccines gave partial protection against the development of DMV/1639/11-induced renal lesions. Although numerically fewer chickens vaccinated with Mass + Conn had interstitial nephritis compared with those vaccinated with Mass + Ark, neither vaccine combination offered greater protection (P < 0.05) than observed in unvaccinated chickens challenged with DMV/1639/11. Mass + Ark vaccinations, applied under commercial conditions in the hatchery (spray) and on-farm (spray), did not protect the trachea or kidney from DMV/1639/11 challenge. Serologic testing of broiler flocks found < 3% (2 of 69) tested to possess specific antibodies to DMV/1639/11, indicating the virus had not become established in the region.

Factors influencing the outcome of infectious bronchitis vaccination and challenge experiments

“…Another important factor to consider is whether SPF chicks or chicks with MDA should be used. Many studies have used commercial chickens with MDA (Winterfield, 1968;Alvarado et al, 2003;Joiner et al, 2007;Gelb et al, 2013) and this continued even once SPF chicks became widely available. Clearly the advantage is that the results obtained relate more closely to the field situation.…”

“…Whilst 1-day-old vaccination has been used in some studies (Toro & Fernandez, 1994;Lin et al, 2005;Martin et al, 2007), vaccination is frequently delayed until approximately 2 weeks (Endo-Munoz & Faragher, 1989;Lambrechts et al, 1993;Liu et al, 2009;Meir et al, 2012;Gelb et al, 2013), 3 weeks (Lim et al, 2012), or even as late as 5 weeks of age (Rosenberger et al, 1976). It is not easy to understand why this might be the case, except that it may be intended to mimic the age at which specific vaccines are applied in the field.…”

“…On the other hand, a big variable is the actual dose of vaccine used in different studies. Some workers simply state that a "recommended dose" was used (Darbyshire & Peters, 1985;Cook et al, 1999;Matthijs et al, 2005;Terregino et al, 2008;De Wit et al, 2011b;Gelb et al, 2013), which may imply that the vaccine was not actually titrated as part of the experimental protection study, but was diluted according to the instructions provided by the manufacturer of that vaccine. In other work, a commonly used dose is log 10 3.0 EID 50 /bird, but higher doses have been used and sometimes titres are expressed as "EID 50 /ml of vaccine", making calculation of the actual dose received by each chick more difficult.…”

Efecto de la suplementación de capsaicina como estimulante inmunológico en pollos Ross

“…Se caracteriza por presentar sintomatología respiratoria como tos, estornudos, estertores traqueales, y si afecta el tracto urogenital, puede presentar trastornos en la producción de huevos y daños en los riñones, dependiendo del tipo de cepa que esté atacando [17,18].…”

Extensive coronavirus-induced membrane rearrangements are not a determinant of pathogenicity

“…IBV is a highly important pathogen of poultry, causing animal welfare problems and extensive economic losses to poultry industries globally. There are numerous strains and serotypes of IBV that cause a broad spectrum of disease ranging from mild respiratory symptoms to nephropathology to severe pathology of the reproductive organs 15 16 17 18 . In addition, live-attenuated vaccine strains are commonly used to protect poultry from virus infection (for example Nobilis IB (MSD Animal Health), Poulvac IB (Zoetis) and Cevac (Ceva)).…”