Protective efficacy of concomitant day-old vaccination with live-attenuated infectious bronchitis virus (IBV) vaccines (1/96 and H120 + PHY.LMV.42) against a Thai QX-like IBV challenge in commercial broilers

Description

Thotsapol Thomrongsuwannakij and co-authors evaluate in 2026 a same-day pairing of two live vaccines against infectious bronchitis virus, a major respiratory disease of commercial chickens. QX-like variants circulating in Thailand evade standard vaccine protection, so hatch-day cover needs strengthening. Seventy day-old broiler chicks were split into vaccinated, challenged control, and unchallenged control groups. Both vaccines went into the eye at hatch, and a Thai QX-like strain served as challenge at three weeks of age.

Protection was judged by windpipe ciliary function scores, a binomial protection score, virus detection, antibody levels, and body weight. Vaccinated birds kept far more windpipe function than challenged controls, reaching full protection on the binomial score while controls lost all ciliary activity, and virus detection fell without reaching significance. Antibody levels after challenge rose above unchallenged controls, yet challenged birds still weighed less, so vaccine cover was judged partial.

Catalog record

Source: https://europepmc.org/article/MED/PMC13500146