Polymicrobial abscess following ovariectomy in a mouse

Preparation of Escherichia coli ghost of anchoring bovine Pasteurella multocida OmpH and its immunoprotective effect

Pasteurella multocida is a pathogen that can infect humans and animals. A ghost is an empty bacterial body devoid of cytoplasm and nucleic acids that can be efficiently presented by antigen-presenting cells. To study a novel ghost vector vaccine with cross-immune protection, we used bacteriophage PhiX174 RF1 and Pasteurella multocida standard strain CVCC393 as templates to amplify the split genes E and OmpH to construct a bidirectional expression vector E'-OmpH-pET28a-ci857-E. This is proposed to prepare a ghost Escherichia coli (engineered bacteria) capable of attaching and producing Pasteurella multocida OmpH on the inner membrane of Escherichia coli (BL21). The aim is to assess the antibody levels and the effectiveness of immune protection by conducting a mouse immunoprotective test. The bidirectional expression vector E'-OmpH-pET28a-ci857-E was successfully constructed. After induction by IPTG, identification by SDS-PAGE, western blot, ghost culture and transmission electron microscope detection, it was proven that the Escherichia coli ghost anchored to Pasteurella multocida OmpH was successfully prepared. The immunoprotective test in mice showed that the antibody levels of Pasteurella multocida inactivated vaccine, OmpH, ghost (aluminum glue adjuvant) and ghost (Freund's adjuvant) on day 9 after immunization were significantly different from those of the PBS control group (P < 0.01). The immune protection rates were 100%, 80%, 75%, and 65%, respectively, and the PBS negative control was 0%, which proved that they all had specific immune protection effects. Therefore, this study lays the foundation for the further study of ghosts as carriers of novel vaccine-presenting proteins.

The Versatility of Opportunistic Infections Caused by Gemella Isolates Is Supported by the Carriage of Virulence Factors From Multiple Origins

The molecular basis of the pathogenesis of the opportunistic invasive infections caused by isolates of the Gemella genus remains largely unknown. Moreover, inconsistencies in the current species assignation were detected after genome-level comparison of 16 public Gemella isolates. A literature search detected that, between the two most pathogenic species, Gemella morbillorum causes about twice the number of cases compared to Gemella haemolysans. These two species shared their mean diseases - sepsis and endocarditis - but differed in causing other syndromes. A number of well-known virulence factors were harbored by all species, such as a manganese transport/adhesin sharing 83% identity from oral endocarditis-causing streptococci. Likewise, all Gemellae carried the genes required for incorporating phosphorylcholine into their cell walls and encoded some choline-binding proteins. In contrast, other proteins were species-specific, which may justify the known epidemiological differences. G. haemolysans, but not G. morbillorum, harbor a gene cluster potentially encoding a polysaccharidic capsule. Species-specific surface determinants also included Rib and MucBP repeats, hemoglobin-binding NEAT domains, peptidases of C5a complement factor and domains that recognize extracellular matrix molecules exposed in damaged heart valves, such as collagen and fibronectin. Surface virulence determinants were associated with several taxonomically dispersed opportunistic genera of the oral microbiota, such as Granulicatella, Parvimonas, and Streptococcus, suggesting the existence of a horizontally transferrable gene reservoir in the oral environment, likely facilitated by close proximity in biofilms and ultimately linked to endocarditis. The identification of the Gemella virulence pool should be implemented in whole genome-based protocols to rationally predict the pathogenic potential in ongoing clinical infections caused by these poorly known bacterial pathogens.