The study of the anti-inflammatory efficacy of KRKA's doxycycline hyclate (Doxatib ®) against infectious bronchitis in chickens
Infectious bronchitis (IB) is a contagious respiratory disease of chickens of worldwide distribution and economic importance. KRKA's Doxatib® includes doxycycline hyclate, which is a tetracycline antibiotic. Known facts of the presence and antiviral effect of doxycycline against RNA viruses, incl. through the activation of the antiviral protein ZAP, as well as the presence of anti-inflammatory effects of doxycycline, including in COVID 19 in humans. The aim of the study was to study the anti-inflammatory activity of doxycycline in infectious bronchitis of chickens. Modeling of infectious bronchitis was carried out by infecting 14 day-old chickens of the Shaver cross, 10x with a dose of the vaccine strain IBV H120. The experimental group of chickens was given the drug Doxatib® (doxycycline) manufactured by Krka, d.d., in accordance with the instructions for the drug. Pathological anatomical autopsy revealed a decrease in inflammatory processes in the thymus and lungs. Luminescent microscopy of the lungs revealed a decrease in interstitial lung inflammation and exudate in chickens of the experimental group, compared with the control group. When analyzing the expression of genes involved in inflammatory processes, the anti-inflammatory effects of the drug doxycycline (Doxatib<sup>® </sup>Krka, d.d.) were established. The found changes in the expression of genes involved in the activation of the inflammatory response are identical to the anti-inflammatory effect of doxycycline in coronavirus infection (COVID 19) in humans and consist in the suppression of pro-inflammatory factors that can increase mortality in coronavirus infections, both in humans and in chickens, NFkB, IL6, FCR.