Vaccination of BALB/c Mice with an Avirulent Mycoplasma pneumoniae P30 Mutant Results in Disease Exacerbation upon Challenge with a Virulent Strain

Abstract

Mycoplasma pneumoniae is a significant human respiratory pathogen that causes high morbidity worldwide. No vaccine to prevent M. pneumoniae infection currently exists, since the mechanisms of pathogenesis are poorly understood. To this end, we constructed a P30 cytadhesin mutant (P-130) with a drastically reduced capacity for binding to erythrocytes and an inability to glide on glass substrates. This mutant was determined to be avirulent and cannot survive in the lungs of BALB/c mice. We also ascertained that the previously identified P30 gliding motility mutant II-3R is avirulent and also cannot be recovered from the lungs of mice after infection. Mutant P130 was then assessed for its efficacy as a live attenuated vaccine candidate in mice after challenge with wild-type M. pneumoniae. After vaccination with the P-130 P30 mutant, mice showed evidence of exacerbated disease upon subsequent challenge with the wild-type strain PI1428, which appears to be driven by a Th17 response and corresponding eosinophilia. Our results are in accordance with other reports of vaccine-induced disease exacerbation in rodents and emphasize the need to better understand the basic mechanisms of M. pneumoniae pathogenesis. Mycoplasma pneumoniae is a chronic human pathogen and the etiological agent of many cases of bronchitis and community-acquired pneumonia. Infection with this bacterium can also cause and/or exacerbate other diseases including asthma, myocarditis, sickle cell disease, and encephalitis. Outbreaks are common at such institutions as military bases, schools, and hospitals, where individuals are in close contact for long periods of time, reflecting the community-acquired nature of infections. Diagnosis is difficult as most medical laboratories do not screen for this pathogen, since quick and inexpensive tests are not readily available. Common first-line ␤-lactam antibiotics are ineffective treatments since mycoplasmas lack a cell wall; consequently, this pathogen is often overlooked during diagnosis of affected individuals, and common treatments do not target the source of the disease. This results in considerable economic and societal hardships due to lost and ineffective work/school time, making this pathogen a burden to public health (1, 42).Several virulence determinants of M. pneumoniae have been previously identified and characterized. This bacterium is thought primarily to exploit an extracellular niche and requires a complex tip structure to attach to its host's mucosal epithelium. The tip structure is also involved in gliding motility and cell division. Densely clustered on the surface of the tip structure are the major cytadhesins P1 and P30 and cytadherence-accessory proteins B/C, which are supported by a framework of interdependent cytoskeletal proteins, including HMW1, HMW2, HMW3, P200, P65, P41, and P24 (reviewed in reference 2). Cytadhesin protein P30 has been shown to be critical for both attachment (11, 32) and gliding motility, although its requirements for each are distinguishable (18). Thus, mutant II-...

Modelling persistentMycoplasma pneumoniaeinfection of human airway epithelium

“…Mycoplasma access to the basolateral compartment may also have been facilitated by epithelial remodelling and the coordinated formation of epithelial furrows, based on the high mycoplasma density commonly observed in these regions. Both mechanisms likely require mycoplasma gliding motility, which is supported by in vivo animal studies (Hara et al, 1974;Hardy et al, 2002;Szczepanek et al, 2012). Regardless of the route, migration to the basal lamina might provide a favourable site for nutrient acquisition and immune evasion and potentiate spread to extrapulmonary sites, as occurs in a significant number of cases (Waites & Talkington, 2004).…”

P40 and P90 from Mpn142 are Targets of Multiple Processing Events on the Surface of Mycoplasma pneumoniae

“…Azithromycin and other macrolides are used for the treatment of infections caused by M. pneumoniae [4], but an increase in the frequency of reports of macrolide resistance, particularly in Europe, Asia and North America, is of major concern [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]. Efficacious vaccines for the prevention of infections caused by M. pneumoniae are yet to be developed and are complicated by the presence of antigens that are capable of evoking an autoimmune response [20]. While the infiltration of neutrophils and lymphocytes is a characteristic immunological hallmark of infections caused by M. pneumoniae , the severity of the response varies widely.…”

“…While the infiltration of neutrophils and lymphocytes is a characteristic immunological hallmark of infections caused by M. pneumoniae , the severity of the response varies widely. In severe cases, the immune response is known to generate immunopathological sequelae, complicating vaccine design [2,20]. …”

In Vitro Spatial and Temporal Analysis of Mycoplasma pneumoniae Colonization of Human Airway Epithelium

“…Mycoplasma-host interactions in vivo typically begin at mucosal barriers (11-13), which we define here as including ciliary motion, mucus production, and tight-junction formation (11, 18). Gliding motility is required for lung colonization in experimentally infected hamsters and mice (19,20), and we speculate that this requirement begins with the need to cross the gel layer mucus and gain access to ciliated airway cells.We previously described the use of normal human bronchial epithelial (NHBE) cells in air-liquid interface (ALI) culture to model M. pneumoniae interactions with the human airway (21) and noted then that impaired gliding motility was correlated with reduced colonization (22). Here, we extend that analysis further in three important ways.…”

“…Mycoplasma-host interactions in vivo typically begin at mucosal barriers (11-13), which we define here as including ciliary motion, mucus production, and tight-junction formation (11, 18). Gliding motility is required for lung colonization in experimentally infected hamsters and mice (19,20), and we speculate that this requirement begins with the need to cross the gel layer mucus and gain access to ciliated airway cells.…”