| Toxoplasma gondii and Chlamydia are two kinds of zoonotic pathogens posing a threat to the health of human beings as well as animals. Pigs are common susceptible host of both T. gondii and Chlamydia, play an important role in transmission of the two micro-organisms, and thus are of public health significance.In the first part of the this study, a serological investigation using an indirect hemagglutination (IHA) test was carried out to determine the seroprevalence of T. gondii infection in pigs in Jiangxi province. A total of1232serum samples were collected from pigs in10administrative districts in Jiangxi, and the specific antibodies were detected in282pigs (22.9%). No infection difference was found between weanling pigs (3.7%) and growing pigs (7.3%)(P>0.05). But lactating sows (OR=15.426,95%CI=6.768-35.159, P<0.01), non-pregnant sows (OR=13.734,95%CI=6.430-29.339, P<0.01), pregnant sows (OR=11.501,95%CI=5.331-24.811, P<0.01), breeding boars (OR=9.019,95%CI=3.801-21.401, P<0.01), fattening pigs (OR=4.925,95%CI=2.065-11.745, P<0.01) had greater risk of acquiring the infection compared to weanling pigs. Pigs in spring (OR=1.709,95%CI=1.134-2.574, P=0.01) and summer (OR=2.069,95%CI=1.341-3.192, P<0.01) faced bigger risk of being infected with T. gondii than the pigs in winter. There is no significant difference in T. gondii seroprevalence between pigs in autumn (16.8%) and winter (16.7%)(P>0.05). This is the first documentation of T. gondii seroprevalence in pigs in Jiangxi province, of which the results indicated that pigs in Jiangxi province are frequently exposed to T. gondi. Integrated strategies are needed to strengthen future prevention and control of T. gondii infection in pigs for the reason that pork is the important source of human infection.In the second part, a total of920serum samples were collected from pigs in11administrative districts in Jiangxi province, and the seroprevalence of Chlamydia infection were investigated by indirect hemagglutination (IHA) test. The specific antibodies were detected in539(58.59%) pigs with the seroprevalence ranging from33.33%(Jingdezhen) to90.91%(Pingxiang) among different cities, and the difference was statistically significant (P<0.05). The seroprevalence of Chlamydia infection varied from22.78%to80.89%among different categories of pigs with statistically significant difference (P<0.05). These results indicated that the Chlamydia is highly prevalent in pigs in Jiangxi province, which should arouse extensive attention.In the third part, a total of138DNA samples were extracted from hilar lymph nodes from pigs in Jiangxi, Jilin, Sichuan, Guangdong provinces and Chongqing Municipality in China, and were detected for the presence of T. gondii by semi-nested PCR based on B1gene. Positive DNA samples were typed at11genetic loci, namely, SAG1,5’-SAG2and3’-SAG2, alternative SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and an apicoplast locus Apico, by using PCR-RFLP. Of138DNA samples,34were positive for T. gondii B1gene. Complete genotyping data for all loci could be obtained from20samples. Three genotypes were revealed (ToxoDB PCR-RFLP genotypes#9,#3, and#10). Sixteen samples (12from Jiangxi,3from Sichuan and1from Chongqing) belong to genotype#9, three samples from Jilin belong to ToxoDB#10, and the other one sample from Guangdong belongs to genotype#3which is Type II variant. This is the first report of genetic typing of T. gondii isolates from pigs in Jiangxi, Jilin, Sichuan provinces and Chongqing Municipality, and the first report of ToxoDB#3T. gondii in pigs in China. The results further confirmed that ToxoDB#9is the predominant lineage in China’s mainland.In the the fourth part, hilar lymph node was collected from the pig died of suspected toxoplasmosis. Then the hilar lymph node was homogenized and innoculated into mice intraperitoneally, and finally the T. gondii strain named TgPJX13was isolated after continuous subculture. Specific semi-nested PCR amplification of B1gene and subsequent sequencing analysis revealed100%identity with that T. gondii B1gene available in GenBank. Genotyping of the isolated T. gondii TgPJX13strain was performed by multi-locus PCR-RFLP at11genetic markers (10nuclear loci, namely, SAG1,5’-SAG2and3’-SAG2, alternative SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and an apicoplast locus Apico), and the results indicated that the TgPJX13strain represents ToxoDB#9. The successful isolation and identification of this new strain provides foundation to elucidate its virulence and biological characteristics.In conclusion, the present study investigated the seroprevalence of T. gondii and Chlamydia infection in pigs in Jiangxi province by IHA, genetically characterized T. gondii isolates from pigs from different localities in China using multilocus PCR-RFLP, and successfully isolated and identified a T. gondii strain from a fattening pig in Jiangxi province through animal inoculation. The results not only filled the blank of related research field, but also provided fundamental data for the prevention and control of toxoplasmosis and chlamydiosis. |
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