85 (5) pp 285

Title: 
Infectious bronchitis virus infections of chickens in Belgium: an epidemiological survey
Author(s): 
P. DE HERDT, M. DE GUSSEM, S. VAN GORP, R. CURRIE
Abstract: 

Between April 2012 and July 2015, cloacal and/or tracheal swab samples were collected from fourhundred and twenty-four Belgian chicken broiler, breeder and layer flocks. All flocks were kept forproduction purposes and presented clinical signs suggestive of an infectious bronchitis virus (IBV)infection. The samples were analyzed by real-time polymerase chain reaction (RT-qPCR) to detectthe presence of ribonucleic acid (RNA) of IBV. When positive, approximately four hundred base pairs(bp) encoding for the hypervariable region of the IBV S1 protein were sequenced. Sequencing results,cycle threshold (Ct) values and vaccination history were used as criteria to try and distinguish vaccinestrains from field strains.Of all samples examined, 22.4% was negative. In 16.4% of the samples that did contain RNAfrom IBV, the genotype could not be determined. In most cases, this was due to the recovery ofRNA quantities below the lower limit of detection of the sequencing PCR. The remaining positivesubmissions predominantly revealed RNA from IBV strains that belonged to the 4/91–793B (46.8%),D388–QX (25.2%), D274-D207 (5.8%) and Massachusetts (4.0%) genotypes. Estimations indicatedthat approximately 58%, 11%, 37% and 46% of these detections, respectively, were vaccine strains.Infections with types CK/CH/Guandong/Xindadi/0903, Ukr/27/2011, NGA/295/2006 and Q1 wereobserved sporadically.The results indicate that IBV infections are highly prevalent in Belgian chickens and that at leasteight different IBV types were circulating during the monitored period. This underlines the necessityof providing flocks with a strong and broad protective immunity against IBV.

Full text: 
pp 285-290
Original article(s)