摘要：
Neospora caninum is a protozoan parasite which can infect many mammals and birds with a worldwide distribution. However, no molecular data are available about the occurrence of N. caninum in pigs. In this study, the serological and molecular prevalence of N. caninum infection in farmed pigs were investigated in Hunan province, China, between January 2017 and December 2018. A total of 1,500 serum samples collected from 10 herds in Hunan province were evaluated using a competitive-inhibition enzyme-linked immunoassay assay (cELISA). The overall seroprevalence of N. caninum in the examined pigs was 1.9%. The seroprevalence of N. caninum ranged from 0.3% to 4.6% among different regions in Hunan province of China (p < .05). DNA was extracted from brain samples, and the Nc-5 gene and ITS-1 region were amplified and then sequenced. Three (0.5%) of the examined 600 brain tissues were found to contain N. caninum DNA. Our phylogenetic analyses indicated that N. caninum samples were classified into two distinct groups. Although the prevalence is low within the pig groups investigated, our results revealed the emergence of N. caninum infection in pigs in China. The finding of the present study provides molecular evidence that the pigs are the natural intermediate host of N. caninum and may have major epidemiological importance.
摘要：
Streptococcus suis is a zoonotic pathogen that harbors anti-oxidative stress genes, which have been reported to be associated with virulence. Serial passage has been widely used to obtain phenotypic variant strains to investigate the functions of important genes. In the present study, S. suis serotype 9 strain DN13 was serially passaged in mice 30 times. The virulence of a single colony from passage 10 (SS9-P10) was found to increase by at least 140-fold as indicated by LD50 values, and the increased virulence was stable for single colonies from passage 20 (SS0-P20) and 30 (SS0-P30). Compared to the parental strain, the mouse-adapted strains were more tolerant to oxidative and high temperature stress. Genome-wide analysis of nucleotide variations found that reverse mutations occurred in seven genes, as indicated by BLAST analysis. Three of the reverse mutation genes or their homologs in other bacteria were reported to be virulence-associated, including ide Ssuis in S. suis, a homolog of malR of Streptococcus pneumoniae, and a homolog of the prepilin peptidase-encoding gene in Legionella pneumophila. However, these genes were not involved in the stress response. Another gene, srtR (stress response transcriptional regulator), encoding an XRE family transcriptional regulator, which had an internal stop in the parental strain, was functionally restored in the adapted strains. Further analysis of DN13 and SS9-P10-background srtR-knock-out and complementing strains supported the contribution of this gene to stress tolerance in vitro and virulence in mice. srtR and its homologs are widely distributed in Gram-positive bacteria including several important human pathogens such as Enterococcus faecium and Clostridioides difficile, indicating similar functions in these bacteria. Taken together, our study identified the first member of the XRE family of transcriptional regulators that is involved in stress tolerance and virulence. It also provides insight into the mechanism of enhanced virulence after serial passage in experimental animals.
期刊：
Journal of Veterinary Medical Science,2019年81(8):1173-1176 ISSN：0916-7250
通讯作者：
Gong, Wenjie;Tu, Changchun
作者机构：
[Gong, Wenjie; Tu, Changchun; Gong, WJ; Tu, CC; Ge, Meng] Acad Mil Med Sci, Inst Mil Vet Med, Changchun 130122, Jilin, Peoples R China.;[Ge, Meng; Li, Run-Cheng] Hunan Agr Univ, Coll Vet Med, Changsha 410128, Hunan, Peoples R China.
通讯机构：
[Gong, WJ; Tu, CC] A;Acad Mil Med Sci, Inst Mil Vet Med, Changchun 130122, Jilin, Peoples R China.
关键词：
virus antibody;virus vaccine;animal;blood;enzyme linked immunosorbent assay;immunology;pig;porcine reproductive and respiratory syndrome;Porcine reproductive and respiratory syndrome virus;serodiagnosis;vaccination;veterinary medicine;Animals;Antibodies, Viral;Enzyme-Linked Immunosorbent Assay;Neutralization Tests;Porcine Reproductive and Respiratory Syndrome;Porcine respiratory and reproductive syndrome virus;Swine;Vaccination;Viral Vaccines
摘要：
Two commercial porcine reproductive and respiratory syndrome virus (PRRSV) antibody ELISA kits (IDEXX and LSI) are currently in extensive use. To determine which kit is more suitable for the evaluation of HP-PRRSV vaccine efficacy, the two kits were used to test 546 serum samples. The agreement between the results was unsatisfactory, with a kappa statistic of 0.681 and a linear correlation coefficient of 0.665. In tests of samples from experimentally vaccinated and PRRSV-negative herds, IDEXX-ELISA identified antibody-positive conversion earlier and showed a higher specificity compared to LSI-ELISA. The serological profile obtained by neutralization testing was closer to that obtained by IDEXX-ELISA than by LSI-ELISA in the late immunization period. The findings reveal that IDEXX-ELISA is the more suitable for the evaluation of antibody response to HP-PRRSV vaccine and for guiding vaccination strategies.
期刊：
VECTOR-BORNE AND ZOONOTIC DISEASES,2019年19(12):945-949 ISSN：1530-3667
通讯作者：
Liu, Guo-Hua;Ge, Meng
作者机构：
[Wang, Yu-Gui; Gui, Bin-Ze; Li, Run-Cheng; Wang, Gui-Ping; Liu, Guo-Hua] Hunan Agr Univ, Coll Vet Med, Hunan Prov Key Lab Prot Engn Anim Vaccines, Changsha 410128, Hunan, Peoples R China;[Li, Run-Cheng; Wang, Gui-Ping; Liu, Guo-Hua] Hunan Coinnovat Ctr Anim Prod Safety, Changsha, Hunan, Peoples R China;[Ge, Meng] Hunan Agr Univ, Coll Vet Med, Hunan Engn Technol Res Ctr Vet Drugs, Changsha 410128, Hunan, Peoples R China
通讯机构：
[Liu, Guo-Hua; Ge, Meng] H;Hunan Agr Univ, Coll Vet Med, Hunan Prov Key Lab Prot Engn Anim Vaccines, Changsha 410128, Hunan, Peoples R China. Hunan Agr Univ, Coll Vet Med, Hunan Engn Technol Res Ctr Vet Drugs, Changsha 410128, Hunan, Peoples R China.
关键词：
Toxoplasma gondii;pigs;risk factors;seroprevalence;subtropical China
摘要：
Toxoplasma gondii infection is prevalent in humans and animals worldwide. In the present study, a total of 612 serum samples were examined using indirect hemagglutination test (IHAT) for T. gondii infection. Antibodies to T. gondii were detected in 49 (8.0%, confidence interval [95% CI]: 5.9-10.2) serum samples (IHA titer >/=1:16). The T. gondii seroprevalence ranged from 4.4% (95% CI: 0-10.5) to 14.3% (95% CI: 0-40.2) among different regions in Hunan province of subtropical China. The highest seroprevalence was found in breeding sows (18.8%). The T. gondii seroprevalence was higher in winter (18.3%, 95% CI: 8.5-28.1) and spring (10.9%, 95% CI: 5.7-16.1) than in summer (6.4%, 95% CI: 2.8-10.1) and autumn (4.9%, 95% CI: 2.2-7.7), and the differences were statistically significant excepting summer. In addition, developmental stage and season were identified as risk factors for T. gondii infection. Our findings revealed the seroprevalence of T. gondii in growth stages of pigs in the Hunan province of subtropical China, indicating that it may cause public health and economic problems. To our knowledge, this is the first report of the comprehensive survey of T. gondii seroprevalence in pigs in the Hunan province of subtropical China.
