Fusobacterium equinum possesses a leukotoxin gene and exhibits leukotoxin activity     

Tadepalli S  Stewart GC  Nagaraja TG  Jang SS  Narayanan SK 《Veterinary microbiology》2008,127(1-2):89-96

Fusobacterium equinum, a gram negative, rod-shaped and an obligate anaerobic bacterium is a newly described species. The organism is associated with necrotic infections of the respiratory tract in horses that include necrotizing pneumonia, pleuritis and paraoral infections. The species is closely related to F. necrophorum that causes liver abscesses in cattle and sheep, calf-diphtheria in cattle, and foot-rot in sheep and cattle. Leukotoxin, an exotoxin, is an important virulence factor in bovine strains of F. necrophorum. Our objective was to examine strains (n=10) of F. equinum for leukotoxin (lktA) gene and its toxic effects on equine leukocytes. Southern hybridization and partial DNA sequencing revealed that all the 10 strains had the lktA gene with greater similarities to F. necrophorum subsp. necrophorum. The secreted leukotoxin was detected in the culture supernatant and its biological activity was determined by viability assays with equine polymorphonuclear cells (PMNs) using flow cytometry. While culture supernatants of four strains (E1, E7, E9, and E10) were highly toxic to equine PMNs; strain E5 was moderately toxic and the remaining strains (E2, E3, E4, E6, and E8) were only mildly toxic. Our data indicated that F. equinum isolates had lktA gene and its product was toxic to equine leukocytes. Therefore, leukotoxin may be an important virulence factor in F. equinum infections.  相似文献   

Molecular detection of Coxiella burnetii in raw meat intended for pet consumption     

Amanda Shapiro  Katrina Bosward  Karen Mathews  Gemma Vincent  John Stenos  Mythili Tadepalli  Jacqueline Norris 《Zoonoses and public health》2020,67(4):443-452

The discovery of antibodies against Coxiella burnetii in cattery‐confined breeding cats indicating prior or current exposure (Shapiro et al., 2015) prompted an investigation into possible sources of infection. One hypothesis was that raw meat diets containing reservoir species may provide a source of C. burnetii transmission. The aim of this pilot study was to determine whether C. burnetii DNA was present in raw meat sold exclusively for companion animal consumption. The sample population consisted of raw meat packages (n = 58) of primarily kangaroo origin, with three to four aliquots (50–120 mg) randomly selected from each package. Genomic DNA was extracted from whole tissue in each of these aliquots using a modified protocol. Three quantitative PCR assays were used for the detection of C. burnetii targeting the IS1111 gene, the heat shock operon htpAB and the C. burnetii outer membrane protein‐coding gene, com1. Coxiella burnetii DNA was detected in 25/58 samples (43%) using the IS1111, htpAB and/or com1 PCR assays and confirmed by DNA sequencing. All samples amplifying a product in the com1 assay also amplified a product in the htpAB and IS1111 assays. A total of 17/58 (29%) packets were positive with all three genes, 4/58 (7%) were positive with two genes (IS1111 and htpAB) and 4/58 (7%) were positive with the IS1111 gene only. Coxiella burnetii DNA was five times more likely to be found in offal than skeletal muscle meat samples. All meat samples in which C. burnetii DNA was found were from kangaroo tissues, while samples labelled as non‐kangaroo meat (n = 4) were negative. Multi‐locus variable number of tandem repeat analysis (MLVA) identified three different genotypes of C. burnetii that have all been identified previously from Australian human clinical Q fever cases. Further investigations are required to determine the potential role of certain raw meats in the transmission of C. burnetii to cats and humans.  相似文献