Aeromonas veronii Is a Lethal Pathogen Isolated from Gut of Infected Labeo rohita: Molecular Insight to Understand the Bacterial Virulence and Its Induced Host Immunity

Abstract

A case of severe mortality in farmed Labeo rohita was investigated to characterize the causative agent. We identified the bacterial strain as Aeromonas veronii isolated from the gut of infected L. rohita by biochemical assay, scanning electron microscopy and 16S rRNA gene sequence analysis. The in vivo challenge experiment showed that the LD50 of A. veronii was 2.2 × 104 CFU/fish. Virulence gene investigation revealed that the isolated A. veronii possesses Aerolysin, Cytotoxic enterotoxin, Serine protease, Dnase and Type III secretion system genes. The isolated strain was resistant to two antibiotics (ampicillin and dicloxacillin) while susceptible to 22 other antibiotics. The study further revealed that A. veronii induced both stresses along with non-specific and specific immune responses marked by elevated cortisol HSP70, HSP90 and IgM levels in the treated L. rohita fingerlings. Although the bacterial pathogen enhances the immune response, the negative effect on fish, including stress, and high mortality, create concern and a need for A. veronii management in L. rohita farms. The knowledge gained from this study would facilitate future research aimed at assessing the pathogenicity of A. veronii, with an emphasis on microbial disease management in other farmed fish species.

Evaluation of biocontrol efficacy of rhizosphere dwelling bacteria for management of Fusarium wilt and Botrytis gray mold of chickpea

“…The bacterial identification has been done based on 16S rRNA gene sequence analysis [ 65 , 66 ]. In this study, the 16S rRNA gene of three antagonistic bacterial isolates against FOC and B. cinerea of chickpea both under in vitro and in vivo conditions were sequenced and identified by BLAST homology analysis of the obtained sequences.…”

Identification and Characterization of Immune-Associated MicroRNAs in Silver Carp (Hypophthalmichthys molitrix) Responding to Aeromonas veronii and LPS Stimulation

“…veronii was a laboratory preservation strain (AMQ40920.1). Referring to the previous description [24], the infection concentration was determined by the median lethal dose (LD50) of bacterial infection, and the bacterial suspension was prepared using sterile physiological saline. Three groups of silver carp were created at random: A. veronii group (AV), LPS group (LPS), and control check group (CK).…”

De novo whole transcriptome analysis of Aeromonas hydrophila isolated from the gut of an infected Labeo rohita

“…For instance, the transcriptome of sturgeon fish, red swamp crayfish and Pacu infected with Aeromonas hydrophila provide a detailed insight on host genes expressed during bacterial infection ( Das and Mukherjee, 1997 ; Jiang et al, 2018 ; Mastrochirico-Filho et al, 2020 ; Liu et al, 2021 ). In our recent work, the immune gene expression profile of Labeo rohita revealed the influence of A. veronii and A. hydrophila on host health, showing that some proteins and genes upregulated might be playing an important role in host resistance during infection ( Kumar et al, 2022 ; Behera et al, 2023 ).…”