The intra-assay CVs for IgG1, IgG2, and IgM were 3

The intra-assay CVs for IgG1, IgG2, and IgM were 3.6%, 1.9%, and 2.7%, respectively. gain during the first month and until weaning was calculated. == Results == HS showed higher (p 0.05) reactivity in calf sera againstH. somnirHsp60 and OMP40 in IgG1and IgG2. In experimental calves, compared to control calves, the reactivity of IgG1against rOMP40 in the second sampling was higher in Limousine calves (p 0.001) and in the other two herds (p 0.05). Serum IgG2antibody activity againstH. somnirHsp60 in the second sampling was higher in experimental calves than in control calves in charolaise (p 0.05) and limousine (p 0.001) herds. The reactivity of IgG2against rOMP40 in the second sampling of experimental calves was higher in herds with Charolaise and Limousine calves (p 0.001) and in crossbred calves (p 0.05). In the third sampling, serum IgG1antibody reactivity PALLD against rOMP40 in Limousine calves was higher (p 0.05) in the experimental group. Among the other evaluated parameters, only SAA in the second sampling in the herd with Charolaise calves and heart rate in the herd with Limousine calves were significantly higher in the control calves (p 0.05). == Conclusion == The application of HS to calves in all herds ALZ-801 had an impact on specific reactivity in IgG1and IgG2classes againstH. somnirOMP40 and rHsp60, antigens which were used for serum production. == Supplementary Information == The online version contains supplementary material available at 10.1186/s12917-024-03895-2. Keywords:OMP40, Hsp60, Immunity, Health protection == Introduction == During the rearing period, respiratory tract diseases are the most expensive illness in beef cattle and are a major health problem in feedlot cattle [1]. Maintaining health is crucial for improving the ALZ-801 growth rate and effectiveness of beef production [2]. Metaphylactic antimicrobial programs are used to prevent and treat bovine respiratory disease (BRD); however, this strategy fails with respect to the prudent use of antimicrobial treatments, promoting the selection of resistance gene determinants and antimicrobial-resistant bacteria [3]. Commercial polyvalent immune serum againstEscherichia coli, SalmonellaDublin andSalmonellaTyphimurium given IV (intravenously) to colostrum-deprived calves protected them against death after oral challenge withE. coliO78:K80(B) [4]. The administration of hyperimmune plasma, especially in cases of passive transfer failure, is advisable for the prophylaxis and treatment of neonatal calf diarrhea, which reduces the use of antibiotics [5]. Commercially available bovine hyperimmune serum (HS) administered to calves at the time of arrival to a feedlot in doses 36 times lower than the recommended label did not affect the incidence and severity of BRD or the number of days of treatment [6]. However, serum produced againstHistophilus somniby cow immunization reduced the incidence of BRD in calves and reduced mortality [7]. Histophilus somniis among the most commonly implicated bacterial pathogens identified using culture methods in BRD cases [8]. Sera obtained from cattle, swine, dogs, horses, and poultry vaccinated with wholeH. somnicells revealed a strong immune response against selectedH. somniantigens, including major outer membrane proteins [9]. The outer membrane ofH. somniis composed of a wide range of proteins, the most abundant of which is the major outer membrane protein (MOMP) called OMP 40 kDa (OMP40) [10]. The cross-reactivity of rabbit antiserum with whole-cell antigens of differentH. somnistrains revealed a reaction with proteins with a molecular mass of approximately 40 kDa [11]. Heat shock protein (HSP) 60 is a highly conserved protein that is widely distributed in nature and found in all prokaryotic and eukaryotic cells. Particularly in bacteria, the expression of Hsp60 on the surface occurs constitutively and increases remarkably during host infection [12]. Immunization of mice with one rHsp60 derived from four common pathogenic bacteria,E. coli, H. somni, Pasteurella multocida, andSalmonellaEnteritidis, led to the production of antibodies that ALZ-801 reacted with their homologous and heterologous antigens [13]. Mouse anti-rHsp60H. somniantibodies have been shown to inhibit in vitro biofilm production by these bacteria [14]. Therefore, two protein antigens.