Objective:To evaluate the clinical value of high-risk human papillomavirus (HPV) viral load for the cervical cancer screening and triage of high-risk HPV positive populations without additional tests.Methods:(1) This study conducted a retrospective analysis of 29 720 women aged 35-64 years who received cervical cancer screening in Quanzhou, China, in 2021. Fourteen high-risk HPV types (including HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68) were detected for cervical cancer primary screening using hybrid capture-chemiluminescence method. High-risk HPV positive samples were further subjected to HPV 16/18 genotyping using hybrid capture-chemiluminescence method. Among them, HPV 16/18 positive women were directly referred to colposcopy, while the other 12 high-risk HPV positive samples were further subjected to liquid based cytology test. Those with abnormal or suspicious cytology were referred to colposcopy. Biopsies were taken for histopathological examination of suspicious or abnormal individuals under colposcopy. (2) Ten cases of colposcopy loss or refusal to undergo examination were excluded, and the data from the 29 710 cases were analyzed. The HPV viral loads of the other 12 high-risk HPV positive populations were focused and evaluated their HPV viral loads for further cervical intraepithelial neoplasia (CIN) Ⅱ and above lesions (CINⅡ +) triage in cervical cancer screening. Results:(1) Among 29 720 women, 2 487 women (8.37%, 2 487/29 720) were positive for high-risk HPV, including 807 women (2.72%, 807/29 720) were positive for HPV 16/18 and 1 680 patients (5.65%, 1 680/29 720) were positive for the other 12 high-risk HPV types. Among 1 680 women who tested positive for the other 12 high-risk HPV types, 573 patients were atypical squamous cell carcinoma of unclear significance or above, 346 patients were CIN Ⅰ, 122 patients were CIN Ⅱ-Ⅲ, 9 patients were squamous cell carcinoma patients, and 4 patients were adenocarcinoma in situ. The immediate risk of CIN Ⅱ + in HPV 16/18 positive women (11.13%) was approximately four times higher than that of other 12 high-risk HPV positive women (2.74%). (2) Through the viral load analysis of the other 12 high-risk HPV types, we found that the viral load of the other 12 high-risk HPV provide a good value for the pathological results, with a clinical cutoff (CO) value of 11.21 relative light unit/CO (RLU/CO) for the CINⅡ + detection. Except for HPV 16/18 positive patients, when the viral load values of the other 12 high-risk HPV types were greater than 10 RLU/CO, these patients had a higher risk of CINⅡ +, with a positive predictive value of 31.29%. CINⅡ + was not found in any of the other 12 high-risk HPV positive with viral load values less than or equal to 10 RLU/CO. Conclusions:Using hybrid capture-chemiluminescence HPV tests for HPV 16/18 genotyping, combined with the viral loads (>10 RLU/CO) of the other 12 high-risk HPV analysis, one could triage HPV positive population without additional tests. Such triage strategy could promote the coverage of cervical cancer screening, particularly where cytology pathologists or economic resources are limited.

In order to establish a serological method for the detection of bovine parainfluenza virus type 3(BPIV3),the prokaryotic expression and purification of BPIV3 HN,NP,F,and P proteins were carried out,and the optimal protein-coated antigen was screened,and an indirect ELISA de-tection method was established.The results showed that the four recombinant proteins of BPIV3,rHN,rNP,rF,and rP were expressed,and the checkerboard titration results showed that rHN pro-tein had the highest P/N value as the coating protein,so it was used for the subsequent method es-tablishment.The optimal reaction conditions for indirect ELISA were found to be:the mass con-centration of the antigen coating was 0.5 mg/L,37 ℃ 1.5 h,5％skim milk,overnight blocking at 4 ℃,serum dilution at 1∶50,incubation at 37 ℃ 1 h,secondary antibody dilution at 1∶10 000 and incubation at 37℃ 0.5 h,substrate reaction conditions were 37℃ for 12 min.The results of speci-ficity experiments showed that the established method could specifically identify BPIV3 antibody-positive serum with a sensitivity of 1∶800,and the coefficient of variation in the detection of intra-and inter-assay repeatability was less than 10％,and the overall coincidence rate of the same batch of samples detected with the SVANOVIR kit was 92.22％.This method was used to detect 192 se-rum samples in Hebei Province,and the positive rate of BPIV3 antibody in serum was 66.15％.The indirect ELISA detection method of BP1V3 antibody constructed in this study is suitable for large-scale clinical serological investigations,and provides valuable data support for the research and de-velopment of BPIV3 antigen and antibody detection kits in China.

In order to investigate the role of sRNA OxyS in the pathogenicity of Salmonella typhi-murium infection,the OxyS gene deletion strain ATCC25241 △OxyS and the back-complemented strain ATCC25241 △OxyS/OxyS of Salmonella typhimurium ATCC25241 were constructed by using λRed homologous recombination technique.We investigated the effect of OxyS deletion on the biological characteristics and pathogenicity of Salmonella typhimurium ATCC25241.The re-sults showed that the deletion of OxyS did not affect the growth rate,the ability of biofilm forma-tion,and the ability of adhesion,invasion and intracellular survival of Salmonella typhimurium,but significantly reduced the motility of Salmonella typhimurium as well as its ability to survive in alkaline and oxidative environments.The results of mouse infection test showed that OxyS dele-tion caused a significant decrease in the virulence of Salmonella typhimurium in mice,and toxicity is reduced obviously.The qPCR results also showed that OxyS deletion could lead to changes in the transcript levels of a number of virulence-related genes of Salmonella typhimurium such as pipB,orf245,csgA,invH,tatA,sipA,sipB,and so on.The above results indicate that OxyS gene affects the biological characteristics and pathogenicity of Salmonella typhimurium and is an important virulence regulator of Salmonella typhimurium.

Objective:To investigate the effects of Jianpi Rougan Xifeng Decoction on the behaviors and the Ca 2+ -CaM-CaMK Ⅱ signaling pathway in the striatum of rats with tic disorder models. Methods:Seventy-two SPF-grade SD male rats were randomly divided into blank group, model group, tiapride group (15.93 mg/kg, intragastric administration), low-dose (4.32 g/kg, intragastric administration), medium-dose (8.64 g/kg, intragastric administration) and high-dose (17.28 g/kg, intragastric administration) Jianpi Rougan Xifeng Decoction groups, with 12 rats in each group. Rats in the blank group and model group were gavaged with 0.5 mg/kg of distilled water while rats in other 4 groups were gavaged with corresponding drugs, all rats were gavaged once a day for 28 days.The evaluations of motor behavior and stereotyped behavior were conducted using the Kadasah scoring method and the Diamond scoring method. Calcium content in the striatum was detected using a calcium assay kit. Immunohistochemical analysis was employed to detect the expression of dopamine transporter (DAT) and inositol 1, 4, 5-triphosphate (IP3) in the striatum of rats. Western blot was used to assess the expression of calmodulin (CaM) and calcium/calmodulin-dependent protein kinase Ⅱ (CaMK Ⅱ) in the striatum. RT-PCR was utilized to detect the expression of CaM and CaMK Ⅱ mRNA in the striatum. All data were processed using SPSS 26.0 software, and comparisons among multiple groups were performed using one-way ANOVA and Kruskal-Wallis test.Results:(1) After four weeks of pharmacological intervention, statistically significant differences were observed in the locomotor activity scores and stereotyped scores among the six groups of rats ( H=41.20, 44.24, both P<0.01). Specifically, the locomotor activity scores(3.00(3.00, 3.25), 1.00(0.75, 1.25), 1.00(0.75, 2.00), 1.00(0, 1.00)) and stereotyped scores(3.00(3.00, 4.00), 1.00(0.75, 2.00), 2.00(0.75, 2.00), 1.00(0, 1.25)) in the tiapride group and the medium- and high-dose Jianpi Rougan Xifeng Decoction groups were significantly lower than those in the model group (all P<0.01). (2) Results from the calcium assay kit revealed statistically significant differences in striatal calcium content among the six groups of rats ( F=146.67, P<0.01). The calcium content in the tiapride group and the medium- and high-dose Jianpi Rougan Xifeng Decoction groups was significantly lower than that in the model group (all P<0.01). Additionally, the calcium content in the medium-dose ((0.40±0.02)mmol/g) and high-dose ((0.30±0.03)mmol/g) Jianpi Rougan Xifeng Decoction groups was lower than that in the low-dose group ((0.48±0.02)mmol/g) (both P<0.01). (3) Immunohistochemical results showed that there were statistically significant differences in the mean optical density values of DAT and IP3 in the striatum among the six groups of rats ( F=25.57, 154.98, both P<0.01). The IP3 mean optical density in the tiapride group and the Jianpi Rougan Xifeng Decoction groups with medium and high doses exhibited lower values compared to the model group (all P<0.05), whereas the DAT mean optical density displayed higher values in these groups compared to the model group (all P<0.05). The low-dose Jianpi Rougan Xifeng Decoction group also exhibited a lower optical density value of IP3 compared to the model group( P<0.05). The optical density values of IP3 (2.68±0.21, 2.40±0.22) in the medium-dose and high-dose Jianpi Rougan Xifeng Decoction groups were lower than that in the low-dose group (4.27±0.23) (both P<0.01). (4) Western blot results indicated that there were statistically significant differences in the protein expression levels of CaM and CaMK Ⅱ in the striatum among the six groups of rats ( F=233.03, 118.60, both P<0.01). The protein expression levels of CaM and CaMK Ⅱ in the tiapride group and the low-dose, medium-dose, and high-dose Jianpi Rougan Xifeng Decoction groups were lower than those in the model group (all P<0.01). The protein expression levels of CaM (1.02±0.06, 0.84±0.02) and CaMK Ⅱ (0.48±0.03, 0.40±0.02) in the medium-dose and high-dose Jianpi Rougan Xifeng Decoction groups were lower than those in the low-dose group (1.21±0.03, 0.57±0.02)) (all P<0.05). Additionally, the protein expression level of CaM in the high-dose Jianpi Rougan Xifeng Decoction group was lower than that in the medium-dose group( P<0.05).(5) The RT-PCR results indicated significant variations in the mRNA expression levels of CaM and CaMK Ⅱ within the striatum across the six groups rats ( F=30.54, 20.78, both P<0.01). The mRNA expression levels of CaM and CaMK Ⅱ in the tiapride group and the high-dose Jianpi Rougan Xifeng Decoction group were lower than those in the model group (both P<0.05). The mRNA expression levels of CaMK Ⅱ (1.38±0.17) in the high-dose Jianpi Rougan Xifeng Decoction group were lower than those in the low-dose group (1.99±0.27) ( P<0.01). Conclusion:Jianpi Rougan Xifeng Decoction can improve locomotor activity and stereotyped behavior in rats with tic disorder model. The mechanism may be through inhibiting the Ca 2+ -CaM-CaMK Ⅱ signaling pathway and regulating the expression of DAT and IP3, thereby modulating the release and recovery of dopamine and reducing the occurrence of tic symptoms.

In order to establish a serological method for the detection of bovine respiratory syncytial virus,the prokaryotic expression of four proteins of BRSV,G,F,P,and M was carried out,and the most suitable coating antigen was screened to establish an indirect ELISA detection method.The results showed that the four recombinant proteins of BRSV,rG,rF,rP and rM were successfully expressed.The results of checkerboard screening showed that the P/N value of rG protein was the largest,which was determined to be the best coating antigen established by indirect ELISA meth-od.The optimal reaction conditions for indirect ELISA were as follows:the mass concentration of rG protein coating was 1 mg/L,37℃ for 2 h;3％BSA 37℃ block for 1 h;Serum was diluted 1∶50 and incubated at 37℃ for 1h;Secondary antibody 1∶5 000 dilution,37℃ for 30min;The color development conditions of the substrate were 37℃ for 15 min;Thirty negative sera were selected,and the cut-off value was determined to be 0.63 by the established indirect ELISA method.The re-sults of the specificity test showed that the indirect ELISA method established in this test only recognized BRSV-positive serum,and did not react with IBRV,BCoV,and BPIV3-positive serum.The results of repeatability test showed that the method had good repeatability,and the coefficient of variation within and between batches was less than 10％.The results of the sensitivity test showed that the BRSV-positive serum was still positive when diluted to 1∶8 192.The indirect ELISA method established in this experiment was used to detect 100 clinical serum samples at the same time,and the total coincidence rate of the two reached 90.48％,the positive coincidence rate was 93.42％,and the negative coincidence rate was 82.75％.The indirect ELISA established in this test can be used for the detection of bovine respiratory syncytial virus in clinical practice.

Objective:To investigate the effects of Jianpi Rougan Xifeng Decoction on the behaviors and the Ca 2+ -CaM-CaMK Ⅱ signaling pathway in the striatum of rats with tic disorder models. Methods:Seventy-two SPF-grade SD male rats were randomly divided into blank group, model group, tiapride group (15.93 mg/kg, intragastric administration), low-dose (4.32 g/kg, intragastric administration), medium-dose (8.64 g/kg, intragastric administration) and high-dose (17.28 g/kg, intragastric administration) Jianpi Rougan Xifeng Decoction groups, with 12 rats in each group. Rats in the blank group and model group were gavaged with 0.5 mg/kg of distilled water while rats in other 4 groups were gavaged with corresponding drugs, all rats were gavaged once a day for 28 days.The evaluations of motor behavior and stereotyped behavior were conducted using the Kadasah scoring method and the Diamond scoring method. Calcium content in the striatum was detected using a calcium assay kit. Immunohistochemical analysis was employed to detect the expression of dopamine transporter (DAT) and inositol 1, 4, 5-triphosphate (IP3) in the striatum of rats. Western blot was used to assess the expression of calmodulin (CaM) and calcium/calmodulin-dependent protein kinase Ⅱ (CaMK Ⅱ) in the striatum. RT-PCR was utilized to detect the expression of CaM and CaMK Ⅱ mRNA in the striatum. All data were processed using SPSS 26.0 software, and comparisons among multiple groups were performed using one-way ANOVA and Kruskal-Wallis test.Results:(1) After four weeks of pharmacological intervention, statistically significant differences were observed in the locomotor activity scores and stereotyped scores among the six groups of rats ( H=41.20, 44.24, both P<0.01). Specifically, the locomotor activity scores(3.00(3.00, 3.25), 1.00(0.75, 1.25), 1.00(0.75, 2.00), 1.00(0, 1.00)) and stereotyped scores(3.00(3.00, 4.00), 1.00(0.75, 2.00), 2.00(0.75, 2.00), 1.00(0, 1.25)) in the tiapride group and the medium- and high-dose Jianpi Rougan Xifeng Decoction groups were significantly lower than those in the model group (all P<0.01). (2) Results from the calcium assay kit revealed statistically significant differences in striatal calcium content among the six groups of rats ( F=146.67, P<0.01). The calcium content in the tiapride group and the medium- and high-dose Jianpi Rougan Xifeng Decoction groups was significantly lower than that in the model group (all P<0.01). Additionally, the calcium content in the medium-dose ((0.40±0.02)mmol/g) and high-dose ((0.30±0.03)mmol/g) Jianpi Rougan Xifeng Decoction groups was lower than that in the low-dose group ((0.48±0.02)mmol/g) (both P<0.01). (3) Immunohistochemical results showed that there were statistically significant differences in the mean optical density values of DAT and IP3 in the striatum among the six groups of rats ( F=25.57, 154.98, both P<0.01). The IP3 mean optical density in the tiapride group and the Jianpi Rougan Xifeng Decoction groups with medium and high doses exhibited lower values compared to the model group (all P<0.05), whereas the DAT mean optical density displayed higher values in these groups compared to the model group (all P<0.05). The low-dose Jianpi Rougan Xifeng Decoction group also exhibited a lower optical density value of IP3 compared to the model group( P<0.05). The optical density values of IP3 (2.68±0.21, 2.40±0.22) in the medium-dose and high-dose Jianpi Rougan Xifeng Decoction groups were lower than that in the low-dose group (4.27±0.23) (both P<0.01). (4) Western blot results indicated that there were statistically significant differences in the protein expression levels of CaM and CaMK Ⅱ in the striatum among the six groups of rats ( F=233.03, 118.60, both P<0.01). The protein expression levels of CaM and CaMK Ⅱ in the tiapride group and the low-dose, medium-dose, and high-dose Jianpi Rougan Xifeng Decoction groups were lower than those in the model group (all P<0.01). The protein expression levels of CaM (1.02±0.06, 0.84±0.02) and CaMK Ⅱ (0.48±0.03, 0.40±0.02) in the medium-dose and high-dose Jianpi Rougan Xifeng Decoction groups were lower than those in the low-dose group (1.21±0.03, 0.57±0.02)) (all P<0.05). Additionally, the protein expression level of CaM in the high-dose Jianpi Rougan Xifeng Decoction group was lower than that in the medium-dose group( P<0.05).(5) The RT-PCR results indicated significant variations in the mRNA expression levels of CaM and CaMK Ⅱ within the striatum across the six groups rats ( F=30.54, 20.78, both P<0.01). The mRNA expression levels of CaM and CaMK Ⅱ in the tiapride group and the high-dose Jianpi Rougan Xifeng Decoction group were lower than those in the model group (both P<0.05). The mRNA expression levels of CaMK Ⅱ (1.38±0.17) in the high-dose Jianpi Rougan Xifeng Decoction group were lower than those in the low-dose group (1.99±0.27) ( P<0.01). Conclusion:Jianpi Rougan Xifeng Decoction can improve locomotor activity and stereotyped behavior in rats with tic disorder model. The mechanism may be through inhibiting the Ca 2+ -CaM-CaMK Ⅱ signaling pathway and regulating the expression of DAT and IP3, thereby modulating the release and recovery of dopamine and reducing the occurrence of tic symptoms.

In order to establish a serological method for the detection of bovine respiratory syncytial virus,the prokaryotic expression of four proteins of BRSV,G,F,P,and M was carried out,and the most suitable coating antigen was screened to establish an indirect ELISA detection method.The results showed that the four recombinant proteins of BRSV,rG,rF,rP and rM were successfully expressed.The results of checkerboard screening showed that the P/N value of rG protein was the largest,which was determined to be the best coating antigen established by indirect ELISA meth-od.The optimal reaction conditions for indirect ELISA were as follows:the mass concentration of rG protein coating was 1 mg/L,37℃ for 2 h;3％BSA 37℃ block for 1 h;Serum was diluted 1∶50 and incubated at 37℃ for 1h;Secondary antibody 1∶5 000 dilution,37℃ for 30min;The color development conditions of the substrate were 37℃ for 15 min;Thirty negative sera were selected,and the cut-off value was determined to be 0.63 by the established indirect ELISA method.The re-sults of the specificity test showed that the indirect ELISA method established in this test only recognized BRSV-positive serum,and did not react with IBRV,BCoV,and BPIV3-positive serum.The results of repeatability test showed that the method had good repeatability,and the coefficient of variation within and between batches was less than 10％.The results of the sensitivity test showed that the BRSV-positive serum was still positive when diluted to 1∶8 192.The indirect ELISA method established in this experiment was used to detect 100 clinical serum samples at the same time,and the total coincidence rate of the two reached 90.48％,the positive coincidence rate was 93.42％,and the negative coincidence rate was 82.75％.The indirect ELISA established in this test can be used for the detection of bovine respiratory syncytial virus in clinical practice.

Objective:To evaluate the clinical value of high-risk human papillomavirus (HPV) viral load for the cervical cancer screening and triage of high-risk HPV positive populations without additional tests.Methods:(1) This study conducted a retrospective analysis of 29 720 women aged 35-64 years who received cervical cancer screening in Quanzhou, China, in 2021. Fourteen high-risk HPV types (including HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, and 68) were detected for cervical cancer primary screening using hybrid capture-chemiluminescence method. High-risk HPV positive samples were further subjected to HPV 16/18 genotyping using hybrid capture-chemiluminescence method. Among them, HPV 16/18 positive women were directly referred to colposcopy, while the other 12 high-risk HPV positive samples were further subjected to liquid based cytology test. Those with abnormal or suspicious cytology were referred to colposcopy. Biopsies were taken for histopathological examination of suspicious or abnormal individuals under colposcopy. (2) Ten cases of colposcopy loss or refusal to undergo examination were excluded, and the data from the 29 710 cases were analyzed. The HPV viral loads of the other 12 high-risk HPV positive populations were focused and evaluated their HPV viral loads for further cervical intraepithelial neoplasia (CIN) Ⅱ and above lesions (CINⅡ +) triage in cervical cancer screening. Results:(1) Among 29 720 women, 2 487 women (8.37%, 2 487/29 720) were positive for high-risk HPV, including 807 women (2.72%, 807/29 720) were positive for HPV 16/18 and 1 680 patients (5.65%, 1 680/29 720) were positive for the other 12 high-risk HPV types. Among 1 680 women who tested positive for the other 12 high-risk HPV types, 573 patients were atypical squamous cell carcinoma of unclear significance or above, 346 patients were CIN Ⅰ, 122 patients were CIN Ⅱ-Ⅲ, 9 patients were squamous cell carcinoma patients, and 4 patients were adenocarcinoma in situ. The immediate risk of CIN Ⅱ + in HPV 16/18 positive women (11.13%) was approximately four times higher than that of other 12 high-risk HPV positive women (2.74%). (2) Through the viral load analysis of the other 12 high-risk HPV types, we found that the viral load of the other 12 high-risk HPV provide a good value for the pathological results, with a clinical cutoff (CO) value of 11.21 relative light unit/CO (RLU/CO) for the CINⅡ + detection. Except for HPV 16/18 positive patients, when the viral load values of the other 12 high-risk HPV types were greater than 10 RLU/CO, these patients had a higher risk of CINⅡ +, with a positive predictive value of 31.29%. CINⅡ + was not found in any of the other 12 high-risk HPV positive with viral load values less than or equal to 10 RLU/CO. Conclusions:Using hybrid capture-chemiluminescence HPV tests for HPV 16/18 genotyping, combined with the viral loads (>10 RLU/CO) of the other 12 high-risk HPV analysis, one could triage HPV positive population without additional tests. Such triage strategy could promote the coverage of cervical cancer screening, particularly where cytology pathologists or economic resources are limited.

In order to establish a serological method for the detection of bovine parainfluenza virus type 3(BPIV3),the prokaryotic expression and purification of BPIV3 HN,NP,F,and P proteins were carried out,and the optimal protein-coated antigen was screened,and an indirect ELISA de-tection method was established.The results showed that the four recombinant proteins of BPIV3,rHN,rNP,rF,and rP were expressed,and the checkerboard titration results showed that rHN pro-tein had the highest P/N value as the coating protein,so it was used for the subsequent method es-tablishment.The optimal reaction conditions for indirect ELISA were found to be:the mass con-centration of the antigen coating was 0.5 mg/L,37 ℃ 1.5 h,5％skim milk,overnight blocking at 4 ℃,serum dilution at 1∶50,incubation at 37 ℃ 1 h,secondary antibody dilution at 1∶10 000 and incubation at 37℃ 0.5 h,substrate reaction conditions were 37℃ for 12 min.The results of speci-ficity experiments showed that the established method could specifically identify BPIV3 antibody-positive serum with a sensitivity of 1∶800,and the coefficient of variation in the detection of intra-and inter-assay repeatability was less than 10％,and the overall coincidence rate of the same batch of samples detected with the SVANOVIR kit was 92.22％.This method was used to detect 192 se-rum samples in Hebei Province,and the positive rate of BPIV3 antibody in serum was 66.15％.The indirect ELISA detection method of BP1V3 antibody constructed in this study is suitable for large-scale clinical serological investigations,and provides valuable data support for the research and de-velopment of BPIV3 antigen and antibody detection kits in China.

In order to investigate the role of sRNA OxyS in the pathogenicity of Salmonella typhi-murium infection,the OxyS gene deletion strain ATCC25241 △OxyS and the back-complemented strain ATCC25241 △OxyS/OxyS of Salmonella typhimurium ATCC25241 were constructed by using λRed homologous recombination technique.We investigated the effect of OxyS deletion on the biological characteristics and pathogenicity of Salmonella typhimurium ATCC25241.The re-sults showed that the deletion of OxyS did not affect the growth rate,the ability of biofilm forma-tion,and the ability of adhesion,invasion and intracellular survival of Salmonella typhimurium,but significantly reduced the motility of Salmonella typhimurium as well as its ability to survive in alkaline and oxidative environments.The results of mouse infection test showed that OxyS dele-tion caused a significant decrease in the virulence of Salmonella typhimurium in mice,and toxicity is reduced obviously.The qPCR results also showed that OxyS deletion could lead to changes in the transcript levels of a number of virulence-related genes of Salmonella typhimurium such as pipB,orf245,csgA,invH,tatA,sipA,sipB,and so on.The above results indicate that OxyS gene affects the biological characteristics and pathogenicity of Salmonella typhimurium and is an important virulence regulator of Salmonella typhimurium.