Demonstration of a capsule on Mycoplasma ovipneumoniae.
OBJECTIVE
To examine Mycoplasma ovipneumoniae for presence of a capsule and its potential role in adherence.


METHODS
17 isolates of M ovipneumoniae and 2 isolates of M arginini, recovered from sheep with respiratory tract disease.


METHODS
Mycoplasmas were cultured in modified Fills broth medium, ovine fetal lung cells, or ovine tracheal ring explants. Pelleted mycoplasmas or ring cultures infected with mycoplasmas were treated with ruthenium red or polycationic ferritin and visualized by transmission electron microscopy. Reactivity of several lectins with the mycoplasmas was studied by use of a microtitration plate agglutination test.


RESULTS
Electron microscopy revealed a large number of M ovipneumoniae cells covered with an electron dense-stained amorphous material suggesting that it was a capsule. Multiple passages of the microorganisms in modified Friis broth medium decreased thickness of the capsule, but not percentage of cells encapsulated. Marked differences were observed when M ovipeumoniae isolates grown in modified Friis broth medium or co-cultured with ovine fetal lung cells were compared for capsular thickness or percentage of encapsulation. In thin sections of ruthenium red-stained tracheal ring cultures, the mycoplasmas appeared to be in close contact with cilia through their capsule. All isolates of M ovipneumoniae reacted strongly with wheat germ agglutinin lectin.


CONCLUSIONS
Mycoplasma ovipneumoniae produces a polysaccharide capsule with variable thickness that is dependent on culture conditions and strain. Morphologic observations suggest that this capsule facilitates adherence of the organism to ciliated epithelium.
Niang
M
M
Department of Microbiology, Immunology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames 50011, USA.
Rosenbusch
R F
RF
Andrews
J J
JJ
Kaeberle
M L
ML
D000371:Agglutination; D000818:Animals; D001422:Bacterial Adhesion; D016667:Bacterial Capsules / Q000378:metabolism / Q000648:ultrastructure*; D002478:Cells, Cultured; D004848:Epithelium / Q000382:microbiology / Q000648:ultrastructure; D037102:Lectins / Q000378:metabolism; D008168:Lung / Q000382:microbiology / Q000648:ultrastructure; D008854:Microscopy, Electron / Q000662:veterinary; D009174:Mycoplasma / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure*; D011019:Pneumonia, Mycoplasma / Q000382:microbiology / Q000662:veterinary*; D012756:Sheep; D012757:Sheep Diseases / Q000382:microbiology*; D014132:Trachea / Q000382:microbiology / Q000648:ultrastructure
D037102:Lectins