Study On The Ultrastructure, Pathogenicity And Membrane Protein Of Mycoplsama Hyopheumoniae MY-99 Strain

According to the ultrastructure of Mycoplasma hyopneumoniae MY-99 strain, we found it ranges from 0.33um to 0.48um without cellwall and its modality various .34-day-old cross-bred pigs were inocuolated Mycoplasma hyopneumoniae MY-99 strain intranasally, and at postinoculation weeks (PIW) 2, the clinical signs of swine enzootic pneumonia (SEP) such as wheeze occurred to 60% inoculated pigs, a few of them coughed; histologic lesions included accumulation of neutrophils and macrophages around bronchus, and the lesions reached the peak at PIW 2 and 4, then increasingly relieved at PIW 6. We isolated Mycoplasma hyopneumoniae from the lungs of the inoculated pigs. Meanwhile, the average daily gain of inoculated pigs decreased significantly compared to the control pigs, 31.05% decreased during postinoculation days 0-14(P< 0.01). 42.01% decreased during postinoculation days I5-28(P<0.01), and 0.1% decreased during postinoculation days 29-42(P>0.05). the liters of the antibody in serum at PIW 2,4,6 were 1:24.2,1:23.9 and 1:22.5 respectively, which indicate that Mycoplasma hyopneumoniae MY-99 strain induced an acute SEP.We extracted membrane protein of Mycoplasma hyopneumoniae MY-99 strain from its different passages' strains MY-99l,MY-993 and rejuvenescence strain MY-992, then analyzed them by SDS-PAGE, the results show that the membrane protein of Mycoplasma hyopneumoniae MY-99 strain mutated during artificial culturing . According to the electrophoretic profiles, the membrane proteins of MY-991 include 7 protein bands: 94.4KD,57.5KD,46.0KD,36.0KD,32.4KD,20.4KD and 16.6KD. The membrane proteins of MY-993 also include 7 protein bands: 94.4KD,57.5KD, 46KD, 41KD,36.0KD,32.4KD and 19.5KD,but the membrane proteins of MY-992 only include 2 protein bands:46KD and 32.4KD. The immunoblotting to the antiserum of MY-991,MY-992 and MY-993, positive serum and negative serum respectively, show that P46 of all the strains reacted to all the sera but negative serum.We transferred the membrane proteins of Mycoplasma hyopneumoniae MY-99 strain to PVDF membrane, dyed and dried, then marked the P46 and sequenced the N-terminal 10 amino acids of P46 by the central laboratory of fundamental medical institute, Chinese medical academy of science. The sequence is: Ala-Glu(Gly)-Lys- Cys-Asn-Gln-Asp-Gly(Tyr)-Gln-Gly.