GapA and CrmA coexpression is essential for Mycoplasma gallisepticum cytadherence and virulence.
It was previously demonstrated that avirulent Mycoplasma gallisepticum strain R(high) (passage 164) is lacking three proteins that are expressed in its virulent progenitor, strain R(low) (passage 15). These proteins were identified as the cytadhesin molecule GapA, the putative cytadhesin-related molecule CrmA, and a component of a high-affinity transporter system, HatA. Complementation of R(high) with wild-type gapA restored expression in the transformant (GT5) but did not restore the cytadherence phenotype and maintained avirulence in chickens. These results suggested that CrmA might play an essential role in the M. gallisepticum cytadherence process. CrmA is encoded by the second gene in the gapA operon and shares significant sequence homology to the ORF6 gene of Mycoplasma pneumoniae, which has been shown to play an accessory role in the cytadherence process. Complementation of R(high) with wild-type crmA resulted in the transformant (SDCA) that lacked the cytadherence and virulence phenotype comparable to that found in R(high) and GT5. In contrast, complementation of R(high) with the entire wild-type gapA operon resulted in the transformant (GCA1) that restored cytadherence to the level found in wild-type R(low). In vivo pathogenesis trials revealed that GCA1 had regained virulence, causing airsacculitis in chickens. These results demonstrate that both GapA and CrmA are required for M. gallisepticum cytadherence and pathogenesis.
Papazisi
L
L
Center of Excellence for Vaccine Research, The University of Connecticut, Storrs 06269, USA.
Frasca
S
S
Gladd
M
M
Liao
X
X
Yogev
D
D
Geary
S J
SJ
D018829:Adhesins, Bacterial / Q000378:metabolism*; D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002645:Chickens / Q000382:microbiology; D009174:Mycoplasma / Q000472:pathogenicity* / Q000502:physiology; D009175:Mycoplasma Infections / Q000382:microbiology / Q000503:physiopathology / Q000662:veterinary*; D011201:Poultry Diseases / Q000382:microbiology* / Q000503:physiopathology; D017422:Sequence Analysis, DNA; D014169:Transformation, Bacterial; D014774:Virulence
D018829:Adhesins, Bacterial; D001426:Bacterial Proteins; C117938:GapA cytadhesin; C089115:ORF6 protein, Bacteria; C490293:ORF6 protein, Mycoplasma pneumoniae