S. Levisohn et al., IN-VIVO VARIATION OF MYCOPLASMA-GALLISEPTICUM ANTIGEN EXPRESSION IN EXPERIMENTALLY INFECTED CHICKENS, Veterinary microbiology, 45(2-3), 1995, pp. 219-231
The antigen expression profiles of Mycoplasma gallisepticum isolates o
btained from tracheal swabs of chickens after aerosol-inoculation with
M. gallisepticum strain R or clonal variant R/E were examined in west
ern immunoblots. A reference anti-M. gallisepticum chicken antiserum a
nd antisera from individual infected chickens as well as monoclonal an
tibodies (mAbs) specific for surface proteins were used to monitor in
vivo antigenic variation. mAbs 1E5 and 12D8, recognizing PvpA and p67a
, recently shown to undergo high-frequency in vitro phase variation, w
ere used for consecutive staining of colony and western immunoblots in
order to distinguish between the resultant phenotypes with respect to
the corresponding epitopes. Marked differences in the expression of m
ajor immunogenic proteins, including p67a, were observed between the t
wo inocula as well as among reisolates recovered at different times of
infection. Comparative western immunoblot analysis of the rapidly cha
nging chicken serum antibody response and reisolates recovered during
the course of an experimental infection with M. gallisepticum R or clo
nal variant R/E suggest that immune modulation may have a key role in
generating surface diversity. In addition, comparison of colony immuno
blots of strain R inoculum and of reisolated colonies from tracheas of
birds 8 days post infection indicated an in vivo selection of the Pvp
A(+)p67a(-) phenotype. This study established that surface antigens of
M. gallisepticum are subjected in vivo to rapid alteration in their e
xpression. This variability may function as a crucial adaptive mechani
sm, enabling the organism to escape from the host immune defense and t
o adapt to the changing host environment at different stages of a natu
ral infection.