Molecular variability of DR-1 and DR-2 within the pvpA gene in Mycoplasma gallisepticum isolates.
A total of 15 Mycoplasma gallisepticum (MG) isolates from Chinese poultry farms and three reference strains (S6, BG44T, and F36) were characterized by nested polymerase chain reaction and sequence analysis for two identical and directly repeated sequences, DR-1 and DR-2, within the putative cytadhesin pvpA gene. The molecular variation patterns of the pvpA genes among the 15 MG isolates were identical to the reference strains S6 and BG44T, that is, a 60 bp deletion in DR-1 and DR-2 and repetition of 1) a proline residue 33 times and 2) a tetrapeptide motif 10 times (Pro-Arg-Pro-X, where X is Met, Gly, Asn, or Gln for 6, 1, 1, or 2 times, respectively). However, the variation pattern is quite different from that of the vaccine strain F36, in which only the DR-1 region is retained, 24 of the 25 peptides comprising the linkage sequence between DR-1 and DR-2 are missing, and the entire DR-2 sequence is deleted. A comparison of the sequences within the DR-1 and DR-2 repeated regions among clinical isolates from different geographic sites suggested that > or = 30 proline residue repeats and 7-10 repeats of the tetrapeptide motif may exert an important role in the functionality of PvpA as an adhesin molecule. Size variation and differences in deletion patterns in the C-terminal coding region of the pvpA gene were observed among the field isolates and vaccine strain F, providing the basis for strain differentiation.
College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China.
Hong-Xia
HX
Jiang
Ji-Rong
JR
Chen
Hua-Ling
HL
Yan
Xu-Ning
XN
Li
Zhang-Liu
ZL
Chen
Zhen-Ling
ZL
Zeng
D018829:Adhesins, Bacterial / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004269:DNA, Bacterial; D014644:Genetic Variation; D008969:Molecular Sequence Data; D045686:Mycoplasma gallisepticum / Q000235:genetics*; D020079:Terminal Repeat Sequences
D018829:Adhesins, Bacterial; D004269:DNA, Bacterial; C410583:pvpA protein, Mycoplasma gallisepticum