Development of an aerosol model of murine respiratory mycoplasmosis in mice

Abstract

Animal models of murine respiratory mycoplasmosis due to Mycoplasma pulmonis provide excellent opportunities to study respiratory disease due to an infectious agent. The purpose of the present study was to develop and characterize an aerosol model for the production of murine respiratory mycoplasmosis in mice. The exposure of mice for 30 min to aerosols generated with a DeVilbiss 45 nebulizer in a nose-only inhalation chamber consistently reproduced typical lesions. The chamber was operated with a nebulizer air flow of 5.3 liters/min at 5.0 lb/in2 and a diluting air flow of 20 liters/min, with the nebulizer containing 5 ml of a suspension of viable M. pulmonis organisms (a concentration between 6 x 105 to 6 x 1010 CFU/ml). Infective aerosol particles of less than a 4.0-p.m median aerodynamic diameter with a geometric standard deviation of approximately 2.0 reached the lungs and were evenly distributed among the different lung lobes. A minimum 1.5-log loss of viability in the M. pulmonis suspension was demonstrated. With the exception of the 50% lethal dose, all of the parameters previously established by intranasal inoculation could be examined with the aerosol model. The major advantages of the aerosol model were excellent reproducibility of exposure (both between different experiments and between animals in a given experiment), the avoidance of anesthetization, and the ability to immediately deposit the majority of the organisms in the lung. The only disadvantage was the requirement for large volumes of mycoplasmal cultures.

Clearance of different strains of Mycoplasma pulmonis from the respiratory tract of C3H/HeN mice

“…Experimental inoculations. The method of aerosolization of M. pulmonis and verification of organism viability has been described previously (9,25). Briefly, mice were exposed to aerosols generated with 107 to i09 M. pulmonis per ml in the nebulizer.…”

“…It has been shown previously that C3H/HeN mice are highly susceptible to Mycoplasma pulmonis infection and disease (8). An aerosol model has been described previously (9), and pulmonary clearance of virulent M. pulmonis by C3H/HeN mice has been reported previously (25). In addition, it has been shown that M. pulmonis strains differ in virulence as lung pathogens (6,15).…”

Large‐scale transposon mutagenesis ofMycoplasma pulmonis

“…Mycoplasma pulmonis strain CT is a murine pathogen originally isolated from a mouse lung and is the agent of murine respiratory mycoplasmosis (Davis et al, 1986). Infection of rats and mice with M. pulmonis offers an outstanding model of chronic inflammatory respiratory disease.…”

Identification of exopolysaccharide‐deficient mutants of Mycoplasma pulmonis

“…Mycoplasma strains used in this study. parent of all other mycoplasma strains used in this studyDavis et al (1986);French et al (2008) CTG-R40Long Vsa protein, non-biofilm forming CTG-R5Short Vsa protein, biofilm forming CTG38Long Vsa protein, non-biofilm forming, indistinguishable from the parental CT strain in all assays used in this study, contains transposon at presumably innocuous site for the purposes of this study, disrupting MYPU_0860 (coding for a conserved hypothetical protein) Schematic of the overlapping MYPU_7410 and 7420 genes and flanking regions. Arrows refer to direction of transcription.…”