{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,8]],"date-time":"2026-07-08T11:56:36Z","timestamp":1783511796691,"version":"3.55.0"},"reference-count":45,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,3,28]],"date-time":"2025-03-28T00:00:00Z","timestamp":1743120000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Hubei Provincial Natural Science Foundation Project","award":["2022CFB945"],"award-info":[{"award-number":["2022CFB945"]}]},{"name":"Hubei Provincial Natural Science Foundation Project","award":["Q20211612"],"award-info":[{"award-number":["Q20211612"]}]},{"name":"Hubei Provincial Department of Education Scientific and Technological Research Project","award":["2022CFB945"],"award-info":[{"award-number":["2022CFB945"]}]},{"name":"Hubei Provincial Department of Education Scientific and Technological Research Project","award":["Q20211612"],"award-info":[{"award-number":["Q20211612"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>Streptococcus suis serotype 2 (SS2) is an important zoonotic pathogen that seriously harms the swine industry and human health. However, its pathogenic mechanisms are largely unknown, and the few virulence factors reported so far are insufficient to systematically explain its infectious and pathogenic mechanisms. In preliminary research, we identified a gene named G22 encoding a hypothetical secreted protein that may be closely associated with the high-level pathogenicity of S. suis. In this study, we constructed deletion and complementation strains of the G22 gene through homologous recombination and explored its roles in the pathogenicity and susceptibility of S. suis to environmental stresses through in vitro and in vivo experiments. The deletion of G22 clearly influenced the typical capsular structure of SS2 and impaired the bacterium\u2019s growth in a medium containing hydrogen peroxide (showing a growth reduction of 32.98% \u00b1 5.23% compared to the wild-type strain SC19, p &lt; 0.001) or with a low pH (with a growth inhibition of 17.44% \u00b1 1.9% relative to the wild-type strain SC19, p &lt; 0.01). \u0394G22 also showed reduced survival in whole blood and in RAW 264.7 macrophages (with a survival reduction of 16.44% \u00b1 2.29% compared to the wild-type, p &lt; 0.001). The deletion of G22 also sharply attenuated the virulence of SS2 in a mouse infection model (reducing the mortality rate by 50% \u00b1 0.04%, p &lt; 0.05). We also demonstrated that G22 is required for the adhesion and invasion of SS2 in host cells. An RNA sequencing analysis revealed that 50 genes were differentially expressed in the \u0394G22 and wild-type strains: 23 upregulated and 37 downregulated. Many of the genes are involved in carbohydrate metabolism and the synthesis of virulence-associated factors. Several genes associated with the phosphotransferase system were significantly upregulated in strain \u0394G22. In summary, G22 plays a role in the morphological development and pathogenesis of the highly virulent SS2 strain SC19.<\/jats:p>","DOI":"10.3390\/microorganisms13040774","type":"journal-article","created":{"date-parts":[[2025,3,28]],"date-time":"2025-03-28T13:36:49Z","timestamp":1743169009000},"page":"774","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Mechanisms Underlying the Effects of Secretory Protein G22 on Biological Characteristics and Virulence of Streptococcus suis"],"prefix":"10.3390","volume":"13","author":[{"given":"Shiyue","family":"Fan","sequence":"first","affiliation":[{"name":"National R&D Center for Serich Agricultural Products Processing, School of Modern Industry for Selenium Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanping","family":"Tan","sequence":"additional","affiliation":[{"name":"National R&D Center for Serich Agricultural Products Processing, School of Modern Industry for Selenium Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhiwei","family":"Li","sequence":"additional","affiliation":[{"name":"Joint International Research Laboratory of Animal Health and Animal Food Safety, College of Veterinary Medicine, Southwest University, Chongqing 400715, China"},{"name":"Division of Infectious Diseases and Geographic Medicine, Department of Medicine, Stanford University, Stanford, CA 94305, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanyan","family":"Zhang","sequence":"additional","affiliation":[{"name":"Engineering Research Center of Feed Protein Resources on Agricultural By-Products, Ministry of Education, Wuhan Polytechnic University, Wuhan 430023, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jinquan","family":"Li","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Agricultural Microbiology, College of Biomedicine and Health, Huazhong Agricultural University, Wuhan 430070, China"},{"name":"State Key Laboratory of Agricultural Microbiology, College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6551-1560","authenticated-orcid":false,"given":"Ye","family":"Feng","sequence":"additional","affiliation":[{"name":"Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou 310029, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yi","family":"He","sequence":"additional","affiliation":[{"name":"National R&D Center for Serich Agricultural Products Processing, School of Modern Industry for Selenium Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoling","family":"Chen","sequence":"additional","affiliation":[{"name":"National R&D Center for Serich Agricultural Products Processing, School of Modern Industry for Selenium Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xingxing","family":"Dong","sequence":"additional","affiliation":[{"name":"National R&D Center for Serich Agricultural Products Processing, School of Modern Industry for Selenium Science and Engineering, Wuhan Polytechnic University, Wuhan 430023, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,3,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1017\/S1466252307001247","article-title":"Streptococcus suis infections in humans: The Chinese experience and the situation in North America","volume":"8","author":"Gottschalk","year":"2007","journal-title":"Anim. Health Res. Rev."},{"key":"ref_2","first-page":"1","article-title":"Streptococcus suis, an important pig pathogen and emerging zoonotic agent\u2014An update on the worldwide distribution based on serotyping and sequence typing","volume":"3","author":"Auger","year":"2019","journal-title":"Emerg. Microbes Infect."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"259","DOI":"10.2217\/fmb.11.149","article-title":"Virulence factors involved in the pathogenesis of the infection caused by the swine pathogen and zoonotic agent Streptococcus suis","volume":"7","author":"Nahuel","year":"2012","journal-title":"Future Microbiol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"477","DOI":"10.4161\/viru.28595","article-title":"Streptococcus suis infection","volume":"5","author":"Feng","year":"2014","journal-title":"Virulence"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Sheng, Q., Xu, Q., Lan, Z., and Wu, Z. (2024). Comparative Genome Analysis of TwoStreptococcus suis Serotype 8 Strains Identifies Two New Virulence-Associated Genes. Animals, 14.","DOI":"10.3390\/ani14040572"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1016\/S0378-1135(00)00188-7","article-title":"Distribution of capsular types and production of muramidase-released protein (MRP) and extracellular factor (EF) of Streptococcus suis strains isolated from diseased pigs in seven European countries","volume":"74","author":"Wisselink","year":"2000","journal-title":"Vet. Microbiol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1538","DOI":"10.1080\/21505594.2021.1936770","article-title":"The biological role of MutT in the pathogenesis of the zoonotic pathogen Streptococcus suis serotype 2","volume":"12","author":"Li","year":"2021","journal-title":"Virulence"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Tang, J., Wang, C., Feng, Y., Yang, W., Song, H., Chen, Z., Yu, H., Pan, X., Zhou, X., and Wang, H. (2006). Streptococcal toxic shock syndrome caused by Streptococcus suis serotype 2. PLoS Med., 3.","DOI":"10.1371\/journal.pmed.0030377"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Yong, H., Shiming, F., Geng, Z., Anusak, K., Xiabing, C., Xingxing, D., Lin, T., and Jinquan, L. (2021). Genome analysis provides insight into hyper-virulence of Streptococcus suis LSM178, a human strain with a novel sequence type 1005. Sci. Rep., 11.","DOI":"10.1038\/s41598-021-03370-0"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"585","DOI":"10.1016\/j.tim.2017.02.005","article-title":"Critical Streptococcus suis Virulence Factors: Are They All Really Critical?","volume":"25","author":"Segura","year":"2017","journal-title":"Trends Microbiol."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Tong, W., Hexiang, J., Fengyang, L., Xuan, J., Jun, W., Shaopeng, W., Yi, S., Yanyan, T., Hong, C., and Yu, S. (2024). O-acetyl-homoserine sulfhydrylase deficient Streptococcus suis serotype 2 strain SC19 becomes an avirulent strain and provides immune protection against homotype infection in mice. Vet. Microbiol., 288.","DOI":"10.1016\/j.vetmic.2023.109943"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"516","DOI":"10.1016\/j.jmii.2019.03.003","article-title":"How Streptococcus suis serotype 2 attempts to avoid attack by host immune defenses","volume":"52","author":"Xia","year":"2019","journal-title":"J. Microbiol. Immunol. Infect."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Willenborg, J., Koczula, A., Fulde, M., Greeff, A.D., Beineke, A., Eisenreich, W., Huber, C., Seitz, M., Valentin-Weigand, P., and Goethe, R. (2016). FlpS, the FNR-like Protein of Streptococcus suis Is an Essential, Oxygen-Sensing Activator of the Arginine Deiminase System. Pathogens, 5.","DOI":"10.3390\/pathogens5030051"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"241","DOI":"10.1128\/IAI.00746-09","article-title":"CcpA and LacD.1 affect temporal regulation of Streptococcus pyogenes virulence genes","volume":"78","author":"Kietzman","year":"2010","journal-title":"Infect. Immun."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1023\/A:1020628909429","article-title":"Global control of sugar metabolism: A gram-positive solution","volume":"82","author":"Fritz","year":"2002","journal-title":"Antonie Van Leeuwenhoek"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1366","DOI":"10.1128\/JB.01013-06","article-title":"Time-resolved determination of the CcpA regulon of Lactococcus lactis subsp. cremoris MG1363","volume":"189","author":"Zomer","year":"2007","journal-title":"J. Bacteriol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1698","DOI":"10.1073\/pnas.0711767105","article-title":"A direct link between carbohydrate utilization and virulence in the major human pathogen group A Streptococcus","volume":"105","author":"Shelburne","year":"2008","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Wen, Z.T., and Burne, R.A. (2003). Functional Genomics Approach to Identifying Genes Required for Biofilm Development by Streptococcus mutans. Appl. Environ. Microbiol., 69.","DOI":"10.1128\/AEM.69.1.722.2003"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1823","DOI":"10.1099\/mic.0.046417-0","article-title":"Role of glucose and CcpA in capsule expression and virulence of Streptococcus suis","volume":"157","author":"Willenborg","year":"2011","journal-title":"Microbiology"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Zhou, Y., Tu, T., Yao, X., Luo, Y., Yang, Z., Ren, M., Zhang, G., Yu, Y., Lu, A., and Wang, Y. (2024). Pan-genome analysis of Streptococcus suis serotype 2 highlights genes associated with virulence and antibiotic resistance. Front. Microbiol., 15.","DOI":"10.3389\/fmicb.2024.1362316"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"948","DOI":"10.1007\/s12275-022-2146-4","article-title":"Deletion of lacD gene affected stress tolerance and virulence of Streptococcus suis serotype 2","volume":"60","author":"Xiaowu","year":"2022","journal-title":"J. Microbiol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"e13810","DOI":"10.15252\/emmm.202013810","article-title":"The global emergence of a novel Streptococcus suis clade associated with human infections","volume":"13","author":"Dong","year":"2021","journal-title":"EMBO Mol. Med."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"914","DOI":"10.3201\/eid1206.051194","article-title":"Human Streptococcus suis outbreak, Sichuan, China","volume":"12","author":"Yu","year":"2006","journal-title":"Emerg. Infect. Dis."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"140","DOI":"10.1006\/plas.2001.1532","article-title":"Thermosensitive Suicide Vectors for Gene Replacement in Streptococcus suis","volume":"46","author":"Takamatsu","year":"2001","journal-title":"Plasmid"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1006\/plas.2000.1510","article-title":"Construction and Characterization of Streptococcus suis\u2014Escherichia coli Shuttle Cloning Vectors","volume":"45","author":"Takamatsu","year":"2001","journal-title":"Plasmid"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Tan, M.F., Liu, W.Q., Zhang, C.Y., Gao, T., Zheng, L.L., Qiu, D.X., Li, L., and Zhou, R. (2017). The involvement of MsmK in pathogenesis of the Streptococcus suis serotype 2. Microbiol. Open, 6.","DOI":"10.1002\/mbo3.433"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1016\/j.micres.2019.04.003","article-title":"Role of ClpX and ClpP in Streptococcus suis serotype 2 stress tolerance and virulence","volume":"223\u2013225","author":"Roy","year":"2019","journal-title":"Microbiol. Res."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Zhang, Y., Li, R., Li, Q., Zhu, Y., Yang, X., Zhao, D., and Zong, B. (2023). Orphan response regulator CovR plays positive regulative functions in the survivability and pathogenicity of Streptococcus suis serotype 2 isolated from a pig. BMC Vet. Res., 19.","DOI":"10.1186\/s12917-023-03808-9"},{"key":"ref_29","doi-asserted-by":"crossref","unstructured":"Zhu, H., Wang, Y., Ni, Y., Zhou, J., Han, L., Yu, Z., Mao, A., Wang, D., Fan, H., and He, K. (2018). The Redox-Sensing Regulator Rex Contributes to the Virulence and Oxidative Stress Response of Streptococcus suis Serotype 2. Front. Cell. Infect. Microbiol., 8.","DOI":"10.3389\/fcimb.2018.00317"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1650","DOI":"10.1128\/IAI.05443-11","article-title":"The CovS\/CovR acid response regulator is required for intracellular survival of group B Streptococcus in macrophages","volume":"80","author":"Cumley","year":"2012","journal-title":"Infect. Immun."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Feng, L., Zhu, J., Chang, H., Gao, X., Gao, C., Wei, X., Yuan, F., and Bei, W. (2016). The CodY regulator is essential for virulence in Streptococcus suis serotype 2. Sci. Rep., 6.","DOI":"10.1038\/srep21241"},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Fan, J., Zhao, L., Hu, Q., Li, S., Li, H., Zhang, Q., Zou, G., Zhang, L., Li, L., and Huang, Q. (2022). Screening for Virulence-Related Genes via a Transposon Mutant Library of Streptococcus suis Serotype 2 Using a Galleria mellonella Larvae Infection Model. Microorganisms, 10.","DOI":"10.3390\/microorganisms10050868"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Servane, P., David, R., Ana\u00efs, B., Masatoshi, O., JeanPhilippe, A., Mariela, S., and Marcelo, G. (2021). Role of Maturation of Lipoproteins in the Pathogenesis of the Infection Caused by Streptococcus suis Serotype 2. Microorganisms, 9.","DOI":"10.3390\/microorganisms9112386"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Liu, L., Zhang, Q., Xu, Z., Huang, J., Zhu, W., Zhang, A., Sun, X., and Jin, M. (2019). HP1717 Contributes to Streptococcus suis Virulence by Inducing an Excessive Inflammatory Response and Influencing the Biosynthesis of the Capsule. Microorganisms, 7.","DOI":"10.3390\/microorganisms7110522"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"82","DOI":"10.1111\/j.1574-6968.2009.01551.x","article-title":"Immunization with SsEno fails to protect mice against challenge with Streptococcus suis serotype 2","volume":"294","author":"Esgleas","year":"2009","journal-title":"FEMS Microbiol. Lett."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"106996","DOI":"10.1016\/j.ijantimicag.2023.106996","article-title":"Methyl anthranilate deteriorates biofilm structure of Streptococcus suis and antagonizes the capsular polysaccharide defence effect","volume":"62","author":"Gao","year":"2023","journal-title":"Int. J. Antimicrob. Agents"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1128\/IAI.00377-19","article-title":"Identification of an Autorepressing Two-Component Signaling System That Modulates Virulence in Streptococcus suis Serotype 2","volume":"87","author":"Zhong","year":"2019","journal-title":"Infect. Immun."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Gu, Q., He, P., Wang, D., Ma, J., Zhong, X., Zhu, Y., Zhang, Y., Bai, Q., Pan, Z., and Yao, H. (2021). An Auto-Regulating Type II Toxin-Antitoxin System Modulates Drug Resistance and Virulence in Streptococcus suis. Front. Microbiol., 12.","DOI":"10.3389\/fmicb.2021.671706"},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"Guo, G., Zhang, Y., Wei, D., Wang, Z., Li, Q., Yu, Y., and Zhang, W. (2024). Contribution of nadR to the cell growth and virulence of Streptococcus suis serotype 2. Vet. Microbiol., 288.","DOI":"10.1016\/j.vetmic.2023.109928"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"634","DOI":"10.1016\/j.jiac.2017.06.006","article-title":"Inhibiting effects of fructanase on competence-stimulating peptide-dependent quorum sensing system in Streptococcus mutans","volume":"23","author":"Suzuki","year":"2017","journal-title":"J. Infect. Chemother."},{"key":"ref_41","first-page":"10","article-title":"The Fructose-Specific Phosphotransferase System of Klebsiella pneumoniae is regulated by global regulator CRP and link to virulence and growth","volume":"86","author":"Disi","year":"2018","journal-title":"Infect. Immun."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Haber, A., Friedman, S., Lobel, L., Burg-Golani, T., Sigal, N., Rose, J., Livnat-Levanon, N., Lewinson, O., and Herskovits, A.A. (2017). L-glutamine Induces Expression of Listeria monocytogenes Virulence Genes. PLoS Pathog., 13.","DOI":"10.1371\/journal.ppat.1006161"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"532","DOI":"10.1080\/03079457.2020.1781791","article-title":"The two-component system, BasSR, is involved in the regulation of biofilm and virulence in avian pathogenic Escherichia coli","volume":"49","author":"Yu","year":"2020","journal-title":"Avian Pathol."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"2434","DOI":"10.1128\/JB.01624-09","article-title":"Utilization of lactose and galactose by Streptococcus mutans: Transport, toxicity, and carbon catabolite repression","volume":"192","author":"Zeng","year":"2010","journal-title":"J. Bacteriol."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Panjaitan, N.S., Horng, Y.T., Chien, C.C., Yang, H.C., You, R.I., and Soo, P.C. (2021). The PTS Components in Klebsiella pneumoniae Affect Bacterial Capsular Polysaccharide Production and Macrophage Phagocytosis Resistance. Microorganisms, 9.","DOI":"10.3390\/microorganisms9020335"}],"container-title":["Microorganisms"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2607\/13\/4\/774\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T17:04:24Z","timestamp":1760029464000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2607\/13\/4\/774"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,3,28]]},"references-count":45,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2025,4]]}},"alternative-id":["microorganisms13040774"],"URL":"https:\/\/doi.org\/10.3390\/microorganisms13040774","relation":{},"ISSN":["2076-2607"],"issn-type":[{"value":"2076-2607","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,3,28]]}}}