Evaluation of unintended 1/96 infectious bronchitis vaccine transmission in broilers after direct contact with vaccinated ones

Abstract

Infectious bronchitis virus is characterised by an extreme degree of variability which deeply affects the first-choice control strategies against the disease. Each country tends to adopt its own protocols and even vaccine producers themselves can also adopt different strategies in attempts to confront local epidemiological concerns. In the present study, we tested the potential environmental persistence, transmission ability and replication capability of a non-directly administrated vaccine strain at a hatchery and during transportation. To this purpose, we examined a single hatchery, where combined vaccination (Mass-like plus 793B-like strains) is commonly administered following the protectotype concept, whereas a single broiler flock receives only the Mass priming. Two groups of solely Mass-primed chicks were kept in contact with chicks vaccinated with both strains, during hatchery procedures and transportation, respectively. A regularly vaccinated control group was selected and all three were monitored by swab sampling until 11 days of age. Vaccine titres were quantified using vaccine-specific real-time RT-PCRs to check the kinetics of both strains. Mass titres were consistent among the groups, while the absence of the 1/96 vaccine strain in unvaccinated chicks confirmed the low risk of unintended vaccine transmission, which could complicate the diagnostic process and the epidemiological scenario.

Comparison of tracheal and choanal cleft swabs and poultry dust samples for detection of Newcastle disease virus and infectious bronchitis virus genome in vaccinated meat chicken flocks

“…A high IBV GC load was detected in dust samples and tracheal swabs at 10 dpv with a subsequent decline in the detection rates and GC load in individual birds at 17 and 24 dpv, followed by increase in GC load at 31 dpv. This profile is in agreement with previous studies that reported vaccine virus shedding from 3 dpv, and a peak in viral load and detection rates at 11 and 14 dpv [ 13 , 14 , 37 ]. Later increase in the viral load could be due to re-excretion of the virus from persisting infection.…”

“…Vaccine and field strains of IBV and NDV have been detected in tracheal, oropharyngeal or choanal cleft swabs for variable lengths of time post infection or vaccination. Different strains of IBV were detected in tracheal tissue [ 12 ], and tracheal [ 13 – 17 ], choanal cleft [ 13 , 18 , 19 ] and oropharyngeal swabs [ 20 ]. Similarly, NDV RNA has been detected from oral [ 21 ], oropharyngeal [ 22 , 23 ] and tracheal [ 24 ] swabs.…”

Vaccine or field strains: the jigsaw pattern of infectious bronchitis virus molecular epidemiology in Poland

“…Notably, 89.3% of the detected vaccine-derived strains were 4/91-like ones. In all 72.8% of the 4/91 detections occurred in farms not adopting this vaccine, as opposed to 6.4% and none of the 1/96 and CR88 detections: the significant difference ( P -value < 0.001) suggests a higher spreading capability of the 4/91 vaccine compared to the 1/96-based one, as previously reported (Franzo et al., 2014; Pellattiero et al., 2018). Several causes could justify the observed scenario, including a higher vaccine shedding or longer persistence.…”

Evaluation of UVC Excimer Lamp (222 nm) Efficacy for Coronavirus Inactivation in an Animal Model

“…Moreover, IBV vaccine kinetics has been previously described in field and experimental conditions [36,40] that supported the suitability of the group size and trial duration for the vaccine circulation and detection, allowing also to compare the herein obtained results with an expected trend of viral replication.…”