Cobra (Naja naja) venom L-amino acid oxidase (NNLAAO70) induces apoptosis and secondary necrosis in human lung epithelial cancer cells.

Snake venom L-amino acid oxidases (LAAOs) are flavoenzymes with diverse physiological and pharmacological effects. These enzymes are found to showcase anticoagulant, antiplatelet, cytotoxicity and other biological effects in bite victims. However, the exact mechanism through which they exhibit several biological properties is not yet fully understood. The current study focussed on the purification of cobra venom LAAO and the functional characterization of purified LAAO. A novel L-amino acid oxidase NNLAAO70 with a molecular weight ~70 kDa was purified from the venom of an Indian spectacled cobra (Naja naja). NNLAAO70 showed high substrate specificity for L-His, L-Leu, and L-Arg during its LAAO activity. It inhibited adenosine di-phosphate (ADP) and collagen-induced platelet aggregation process in a dosedependent manner. About 60% inhibition of collagen-induced and 40% inhibition of ADP-induced platelet aggregation was observed with a 40 µg/ml dose of NNLAAO70. NNLAAO70 exhibited bactericidal activity on Bacillus subtilis, Escherichia coli, Bacillus megaterium, and Pseudomonas fluorescens. NNLAAO70 also showed cytotoxicity on A549 cells in vitro. It showed severe bactericidal activity on P. fluorescens and lysed 55% of cells. NNLAAO70 also exhibited drastic cytotoxicity on A549 cells. At 1 lg/ml dosage, it demonstrated a 60% reduction in A549 viability and induced apoptosis upon 24-h incubation. H2O2 released during oxidative deamination reactions played a major role in NNLAAO70-induced cytotoxicity. NNLAAO70 significantly increased intracellular reactive oxygen species (ROS) levels in A549 cells by six fold when compared to untreated cells. Oxidative stress-mediated cell injury is the primary cause of NNLAAO70-induced apoptosis in A549 cells and prolonged oxidative stress caused DNA fragmentation and activated cellular secondary necrosis.

Serotyping, antibiogram, and detection of bacterial pathogens associated with bovine respiratory disease in selected areas of Ethiopia.

BACKGROUND: Bovine Respiratory Disease (BRD) is a multifactorial and economically important illness of cattle. The current study was designed to characterize the major bacterial pathogens associated with BRD and determine the antibiotic susceptibility patterns of isolates. Samples were collected from 400 pneumonic cases of cattle. RESULTS: Laboratory assay revealed isolation of 376 (94.0%) bacterial pathogens. The most prevalent bacterial pathogens recovered were Mannheimia haemolytica (M. haemolytica) followed by Pasteurella multocida (P. multocida), Histophilus somni (H. somni), and Bibersteinia trehalosi (B. trehalosi) from 191 (50.80%), 81 (21.54%), 56 (14.89%), and 48 (12.77%) samples, respectively. M. haemolytica strains were confirmed using multiplex PCR assay through the amplification of PHSSA (~ 325 bp) and Rpt2 (~ 1022 bp) genes. Capsular typing of P. multocida revealed amplification of serogroup A (hyaD-hyaC) gene (~ 1044 bp) and serogroup D (dcbF) gene (~ 657 bp). B. trehalosi isolates displayed amplification of the sodA gene (~ 144 bp). Besides, serotyping of M. haemolytica showed the distribution of serotype A:1 (82.20%), A:2 (10.47%), and A:6 (7.33%). Whereas, biotyping of P. multocida revealed a higher prevalence of biotype A:3 (83.95%), then A:1 (8.64%), A:2 (4.94%), and A:12 (2.47%). The majority of the retrieved isolates showed remarkable susceptibility to enrofloxacin, ciprofloxacin, sulfamethoxazole-trimethoprim, florfenicol, and ceftiofur (100%). Besides, varying degree of antimicrobial resistance was observed against streptomycin, gentamicin, penicillin-G, and ampicillin. CONCLUSIONS: The current findings confirmed that M. haemolytica (A:1) strain is the most common bacterial pathogen identified from BRD cases in the study areas of Ethiopia. Hence, continuous outbreak monitoring and evaluation of antibiotics susceptibility patterns of bacterial pathogens associated with BRD are indispensable to reduce the impact of BRD in the study areas. Further investigation of bacterial pathogens and genotypic analysis of pathogens from a wider area of the country is essential to design a cost-efficient control strategy.