The effect of using several infectious bronchitis vaccines on the expression of TLR3 in the broiler trachea and kidney

The poultry sector is a relatively recent yet rapidly growing industry, having been established in the early twentieth century, it provides a protein source for the human population. Infectious bronchitis virus is the most rife virus in the poultry sector, causes titanic economic loss with mortality rates reaching up to 90%. During IBV infection, TLR3, TLR7 are believed to recognize viral RNA, triggering immune responses that restrict viral replication and dissemination. To protect poultry inactivated or live-attenuated vaccines are administered. The presence of diverse mutant serotypes poses challenges in vaccine design and efficacy. Our study aimed to evaluate the protective efficacy of different IBV vaccines by assessing TLR3 gene expression following immunization with either variant or classical IBV vaccine strains. This was achieved through the use of 160 one-day-old Ross 308 broiler chicks divided into four different groups (N=40) and vaccinated with either the variant or classical IBV vaccine or with both at distenic vaccination programs. Then the trachea and kidney were collected 1, 3, 7, 14, 16, and 21 days post-vaccination to assess TLR3 gene expression by using qpcr with specific primers. The results show that all vaccinated groups increased TLR3 gene expression on the third and sixteenth day post-vaccinationthis lead to concluded that the use of variant or classical IBV vaccine strains in broilers causes an increase in TlR gene expression in the kidney and the trachea, and the combination of variant or classical IBV can increase the efficacy of vaccination due to increased TLR3 expression in broilers