Efficacy and safety of a novel DNA immunostimulant in cattle

Abstract

Four studies were performed to evaluate efficacy (Studies 1 and 2) and safety (Studies 3 and 4) of a novel DNA immunostimulant (Zelnate, Bayer Healthcare) in cattle. Zelnate (ZEL) was administered concurrently with (Study 1) or 24 hours after (Study 2) a Mannheimia haemolytica (Mh) challenge. Holstein steers (3 to 4 months of age; n=32/treatment, Study 1; n=40/treatment, Study 2) received either ZEL or a negative control (CON) on day 0 (Study 1) or day 1 (Study 2). Calves were challenged intratracheally with 60 mL of Mh (10 to the 7th power CFUs/mL, Study 1; 10 to the 8th power CFUs/mL, Study 2) on day 0 and clinically observed to day 5. Lung scores were obtained at the time of premature death or after necropsy on day 5. ZEL mitigated lung lesions in this Mh model, compared to the CON (Studies 1 and 2), and significantly reduced mortality compared to the CON (P < 0.05; Study 2). ZEL was shown to be safe at the injection site (Study 3) and among large populations in different field scenarios (Study 4). ZEL demonstrated efficacy by mitigating lung lesions (Studies 1 and 2) and decreasing mortality (Study 2) in this Mh disease model. Studies 3 and 4 confirmed that ZEL is safe for use in cattle.