Mannheimia haemolyticain bovine respiratory disease: immunogens, potential immunogens, and vaccines

Abstract

Mannheimia haemolytica is the major cause of severe pneumonia in bovine respiratory disease (BRD). Early M. haemolytica bacterins were either ineffective or even enhanced disease in vaccinated cattle, which led to studies of the bacterium's virulence factors and potential immunogens to determine ways to improve vaccines. Studies have focused on the capsule, lipopolysaccharide, various adhesins, extracellular enzymes, outer membrane proteins, and leukotoxin (LKT) resulting in a strong database for understanding immune responses to the bacterium and production of more efficacious vaccines. The importance of immunity to LKT and to surface antigens in stimulating immunity led to studies of individual native or recombinant antigens, bacterial extracts, live-attenuated or mutant organisms, culture supernatants, combined bacterin-toxoids, outer membrane vesicles, and bacterial ghosts. Efficacy of several of these potential vaccines can be shown following experimental M. haemolytica challenge; however, efficacy in field trials is harder to determine due to the complexity of factors and etiologic agents involved in naturally occurring BRD. Studies of potential vaccines have led current commercial vaccines, which are composed primarily of culture supernatant, bacterin-toxoid, or live mutant bacteria. Several of those can be augmented experimentally by addition of recombinant LKT or outer membrane proteins.

Microbial diversity involved in the etiology of a bovine respiratory disease outbreak in a dairy calf rearing unit

“…M. haemolytica is a natural inhabitant of the upper respiratory tract of the bovine species, occasionally it may develop BRD outbreaks [42]. In this study, no BALF sample analyzed was positive for this bacterium.…”

Post-Translational Protein Deimination Signatures in Serum and Serum-Extracellular Vesicles of Bos taurus Reveal Immune, Anti-Pathogenic, Anti-Viral, Metabolic and Cancer-Related Pathways for Deimination

“…F95-enrichment for deiminated proteins from serum and serum-EVs revealed a range of immunological, metabolic and gene regulatory proteins as candidates for this post-translational modification, therefore indicating hitherto under-recognized modes for protein-moonlighting of these proteins in bovine immunity and physiology. Few studies have hitherto assessed roles for PADs and deimination in cattle [22,23,42], while a range of studies have been carried out on EVs in relation to cattle immunity, fertility and development [54,57,60,61,63,65,68,74,78,83,85,88,90]. Export of post-translationally modified proteins, such as deiminated proteins in the current study, has not been assessed before in cattle serum.…”

Differences between predicted outer membrane proteins of genotype 1 and 2 Mannheimia haemolytica

“…They facilitate the exchange of nutrients over the outer membrane and can have important roles in pathogenesis [28,29]. M. haemolytcia ompA encodes a porin protein that has been well researched for both its role in M. haemolytica pathogenicity, and for its potential as a vaccine candidate (see [30] for review of M haemolytica OmpA). This protein has adhesive properties, as it binds to cell-surface fibronectin [31] and lactoferrin [32].…”