NADH oxidase of Mycoplasma hyopneumoniae functions as a potential mediator of virulence

Abstract

Background Mycoplasma hyopneumoniae (M. hyopneumoniae) is the etiological agent of enzootic pneumonia, a highly infectious swine respiratory disease that distributed worldwide. The pathogenesis and virulence factors of M. hyopneumoniae are not fully clarified. As an important virulence factor of bacteria, nicotinamide adenine dinucleotide (NADH) oxidase (NOX) participates in host-pathogen interaction, however, the function of NOX involved in the pathogenesis of M. hyopneumoniae is not clear. Results In this study, significant differences in NOX transcription expression levels among different strains of M. hyopneumoniae differed in virulence were identified, suggesting that NOX may be correlated with M. hyopneumoniae virulence. The nox gene of M. hyopneumoniae was cloned and expressed in Escherichia coli, and polyclonal antibodies against recombinant NOX (rNOX) were prepared. We confirmed the enzymatic activity of rNOX based on its capacity to oxidize NADH to NAD+. Flow cytometry analysis demonstrated the surface localization of NOX, and subcellular localization analysis further demonstrated that NOX exists in both the cytoplasm and cell membrane. rNOX was depicted to mediate adhesion to immortalized porcine bronchial epithelial cells (hTERT-PBECs). Pre-neutralizing M. hyopneumoniae with anti-rNOX antibody resulted in a more than 55% reduction in the adhesion rate of high- and low-virulence M. hyopneumoniae strains to hTERT-PBECs. Moreover, a significant difference appeared in the decline in CCU50 titer between virulent (168) and virulence-attenuated (168L) strains. NOX not only recognized and interacted with host fibronectin but also induced cellular oxidative stress and apoptosis in hTERT-PBECs. The release of lactate dehydrogenase by NOX in hTERT-PBECs was positively correlated with the virulence of M. hyopneumoniae strains. Conclusions NOX is considered to be a potential virulence factor of M. hyopneumoniae and may play a significant role in mediating its pathogenesis.

Hijacking of Host Plasminogen by Mesomycoplasma ( Mycoplasma ) hyopneumoniae via GAPDH: an Important Virulence Mechanism To Promote Adhesion and Extracellular Matrix Degradation

“…Currently, many virulence factors have been identified for M. hyopneumoniae , and their roles include adhesion, invasion, and intracellular proliferation; however, the molecular mechanisms underlying infection and pathogenesis remain unclear. Recently, in addition to typical adhesins such as P97, P102, and P146 ( 5 , 23 – 25 ), several metabolic enzymes, including EF-Tu, FBA, NOX, and NFOR, were described as virulence factors ( 8 – 12 ). They play important roles in the interaction between the host and the pathogen during Mycoplasma infections.…”

“…Additionally, other less typical adhesins, such as some enzymes that moonlight as adhesion proteins, were reported in recent years. For example, NAD oxidase (NOX), NAD-dependent flavin oxidoreductase (NFOR), elongation factor thermo unstable (EF-Tu), and fructose-1,6-bisphosphate aldolase (FBA) are some adhesion molecules of M. hyopneumoniae that have been identified to date ( 8 – 12 ), and many more likely remain to be revealed.…”

Discrimination of mycoplasma infection using machine learning models trained on autofluorescence signatures of host cells

“…Mycoplasma NADH oxidase is reported to be a potential mediator of virulence, [22][23][24] implying that mycoplasma infection causes an increase in the NADH oxidase activity in host cells. NADH is a major cellular autofluorescence molecule with excitation and emission peaks of 330-360 nm and 440-470 nm, respectively.…”