Characterization of Aeromonas hydrophila Strains of Clinical, Animal, and Environmental Origin Expressing the O:34 Antigen

Abstract

A collection of Aeromonas strains of different origins were characterized for isolates expressing the O:34 somatic antigen. Of over 200 strains tested, approximately 14% belonged to serogroup O:34 with >85% of these strains identified as A. hydrophila regardless of source. A subset of 14 A. hydrophila O:34 strains were further analyzed for a number of structural and pathogenic features. Most O:34 strains expressed similar whole-cell protein profiles with regards to minor bands, but major band differences were noted in outer membrane proteins (OMPs) migrating between the 31K and 58K region. OMP profiles could be subdivided into three distinct patterns. All O:34 strains expressed a heterogeneous O polysaccharide side chain profile in their lipopolysaccharide (LPS), although some variation in the electrophoretic migration of lower and higher molecular weight LPS bands was noted. Polyclonal antisera raised against a 45-K OMP-associated protein of one O:34 strain (AH-195) reacted in immunoblot assays with a major 43 to 46-K OMP in 11 of 14 (79%) O:34 strains tested. Most O:34 strains (69%) were found to be pathogenic in mice with LD-50 values (i.p.) of <1.0 x 10(7) CFU; pathogenicity appeared to correlate best with elevated protease activity. The collective results suggest significant differences in both structural and pathogenic properties between some members of the O:34 group originating from human and nonhuman (fish, water) sources.

Transcriptional profiles of multiple genes in the anterior kidney of channel catfish vaccinated with an attenuated Aeromonas hydrophila

“…Furthermore, live attenuated vaccines such as aroA mutant and transposon Tn916-generated mutant have been reported to confer significant protection against homologous A. hydrophila challenge [25,26]. However, it is well known that A. hydrophila is very heterogeneous biochemically and serologically, which is the biggest obstacle in developing effective commercial vaccine against A. hydrophila [23,27]. To prevent future disease outbreaks caused by the highly virulent West Alabama 2009 isolates of A. hydrophila, an attenuated vaccine AL09-71 NþR specifically targeting A. hydrophila AL09-71 was developed [28].…”

Further studies on biochemical characteristics and serologic properties of the genus Aeromonas

“…By using the typing system of Sakazaki and Shimada (19), several important Aeromonas serogroups have been defined. These include serogroup O:11, which is responsible for serious invasive clinical infections such as septicemia, meningitis, and peritonitis (13), and serogroup O:34, which is responsible for human wound infections such as myonecrosis and epizootic outbreaks of septicemia in goldfish (12,17).…”

Aeromonas Flagella and Colonisation Mechanisms

“…Initial electrophoretic studies on aeromonad LPS demonstrated three main patterns, the first being a major ladder-like pattern that is often seen in the enterobacteria and is associated with smooth (S) LPS. The second is characterised by the presence of some O-antigen chains demonstrating a homogeneous pattern and the third a rough (R) or semi-rough pattern in which no O-antigen is present and there is usually one main band present representing the core (Khashe, Hill, & Janda, 1996;Kokka, Vedros, & Janda, 1990;Tso & Dooley, 1995). A number of aeromonad LPS O-antigen serogroups have been shown to be regulated by heat, these being O:13, O:33, O:34 and O:44.…”