Streptococcus agalactiae is an important pathogen in fish, causing great losses of intensive tilapia farming. To develop a potential live attenuated vaccine, a re-attenuated S. agalactiae (named TFJ-ery) was developed from a natural low-virulence S. agalactiae strain TFJ0901 through selection of resistance to erythromycin. The biological characteristics, virulence, stability and the immunization protective efficacy to tilapia of TFJ-ery were determined. The results indicated that TFJ-ery grew at a slower rate than TFJ0901. The capsule thickness of TFJ-ery was significantly less (p < 0.05) than TFJ0901. When Nile tilapia were intraperitoneally (IP) injected with TFJ-ery, the mortality of fish was decreased than that injected with TFJ0901. The RPS of fish immunized with TFJ-ery at a dose of 5.0 × 107 CFU was 95.00%, 93.02% and 100.00% at 4, 8 and 16 weeks post-vaccination, respectively. ELISA results showed that the vaccinated fish produced significantly higher (p < 0.05) antibody titres compared to those of control at 2 or 4 weeks post-vaccination. Taken together, our results suggest that erythromycin could be used to attenuate S. agalactiae, and TFJ-ery is a potent attenuated vaccine candidate to protect tilapia against S. agalactiae infections.

Streptococcus agalactiae is a major pathogen of tilapia causing significant economic losses for the global aquatic industry yearly. To elucidate the role of cel-EIIB protein-mediated phosphotransferase systems (PTS) in the virulence regulation of S. agalactiae, cel-EIIB gene deletion in a virulent strain THN0901 was achieved by homologous recombination. The cellobiose utilization of △cel-EIIB strain was significantly decreased relative to S.a.THN0901 strain incubating in LB with 10 mg/ml cellobiose (p < 0.05). The biofilm formation ability of △cel-EIIB strain was also significantly decreased when cultured in BHI medium (p < 0.05). Under a lower infection dose, the accumulative mortality of tilapia caused by △cel-EIIB strain was dramatically decreased (20%), of which S.a.THN0901 strain and △cel-EIIB::i strain were 53.33% and 50%, respectively. The competition experience using tilapia model indicated the invasion and colonization ability of △cel-EIIB strain was significantly weaker than that of S.a.THN0901 strain (p < 0.05). Compared to △cel-EIIB::i strain, the mRNA expression of csrS, csrR, rgfA, rgfC, bgrR and bgrS was significantly downregulated in △cel-EIIB strain (p < 0.05). In conclusion, cel-EIIB protein-mediated cel-PTS not only contributes to biofilm formation and virulence regulation, but also plays an important role in the invasion and colonization of S. agalactiae.

Journal of Fish DiseasesVolume 37, Issue 12 p. 1067-1072 Short Communication Outbreak of Streptococcus agalactiae infection in barcoo grunter, Scortum barcoo (McCulloch & Waite), in an intensive fish farm in China L Liu, L Liu Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaThese authors contribute to this work equally.Search for more papers by this authorY W Li, Y W Li Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaThese authors contribute to this work equally.Search for more papers by this authorR Z He, R Z He Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaSearch for more papers by this authorX X Xiao, X X Xiao Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaSearch for more papers by this authorX Zhang, X Zhang College of Animal Sciences, South China Agricultural University, Guangzhou, ChinaSearch for more papers by this authorY L Su, Y L Su Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaSearch for more papers by this authorJ Wang, J Wang Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaSearch for more papers by this authorA X Li, Corresponding Author A X Li Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China Correspondence A X Li, State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, 135 Xingang West Road, Guangzhou 510275, Guangdong Province, China (e-mail: [email protected])Search for more papers by this author L Liu, L Liu Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaThese authors contribute to this work equally.Search for more papers by this authorY W Li, Y W Li Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaThese authors contribute to this work equally.Search for more papers by this authorR Z He, R Z He Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaSearch for more papers by this authorX X Xiao, X X Xiao Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaSearch for more papers by this authorX Zhang, X Zhang College of Animal Sciences, South China Agricultural University, Guangzhou, ChinaSearch for more papers by this authorY L Su, Y L Su Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaSearch for more papers by this authorJ Wang, J Wang Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, ChinaSearch for more papers by this authorA X Li, Corresponding Author A X Li Key Laboratory for Aquatic Products Safety of Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China Correspondence A X Li, State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory for Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, 135 Xingang West Road, Guangzhou 510275, Guangdong Province, China (e-mail: [email protected])Search for more papers by this author First published: 07 October 2013 https://doi.org/10.1111/jfd.12187Citations: 41 Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Reference Al-Marzouk A., Duremdez R., Yuasa K., Al-Zenki S., Al-Gharabally H. & Munday B. (2005) Fish kill of mullet Liza klunzingeri in Kuwait Bay: the role of Streptococcus agalactiae and the influence of temperature. In: Diseases in Asian Aquaculture V (ed. by P. Walker, R. Lester & M.G. Bondad-Reantaso), pp. 143–153. Fish Health Section, Asian Fisheries Society, Manila. Amal M.N.A., Zamri-Saad M., Iftikhar A.R., Siti-Zahrah A., Aziel S. & Fahmi S. (2012) An outbreak of Streptococcus agalactiae infection in cage-cultured golden pompano, Trachinotus blochii (Lacépède), in Malaysia. Journal of Fish Diseases 35, 849–852. Azad I.S., Al-Marzouk A., James C.M., Almatar S., Al-Gharabally H. & Qasem J.A. (2012) Outbreak of natural Streptococcosis in hatchery produced silver pomfret (Pampus argenteus Euphrasen) larvae in Kuwait. Aquaculture 330–333, 15–20. Baeck G.W., Kim J.H., Gomez D.K. & Park S.C. (2006) Isolation and characterization of Streptococcus sp. from diseased flounder (Paralichthys olivaceus) in Jeju Island. Journal of Veterinary Science 7, 53–58. Baya A.M., Lupiani B., Hetrick F.M., Roberson B.S., Lukacovic R., May E. & Poukish C. (1990) Association of Streptococcus sp. with fish mortalities in the Chesapeake Bay and its tributaries. Journal of Fish Diseases 13, 251–253. Bromage E.S., Thomas A. & Owens L. (1999) Streptococcus iniae, a bacterial infection in barramundi Lates calcarifer. Diseases of Aquatic Organisms 36, 177–181. Chen K.C., Ma L.S., Shi Y., Zhao J. & Zhu X.P. (2011) Genetic diversity analysis of cultured populations of jade perch (Scortum barcoo) in China using AFLP markers. Journal of Agricultural Science and Technology 4, 455–461. Chen M., Li L.P., Wang R., Liang W.W., Huang Y., Li J., Lei A.Y., Huang W.Y. & Gan X. (2012) PCR detection and PFGE genotype analyses of streptococcal clinical isolates from tilapia in China. Veterinary Microbiology 159, 526–530. Eldar A., Bejerano Y., Livoff A., Horovitcz A. & Bercovier H. (1995) Experimental streptococcal meningo-encephalitis in cultured fish. Veterinary Microbiology 43, 33–40. Evans J.J., Klesius P.H., Gilbert P.M., Shoemaker C.A., Al Sarawi M.A., Landsberg J., Duremdez R., Al-Marzouk A. & Al-Zenki S. (2002) Characterization of β-haemolytic Group B Streptococcus agalactiae in cultured seabream, Sparus auratus L., and wild mullet, Liza klunzingeri (Day), in Kuwait. Journal of Fish Diseases 25, 505–513. Geng Y., Wang K.Y., Huang X.L., Chen D.F., Li C.W., Ren S.Y., Liao Y.T., Zhou Z.Y., Liu Q.F., Du Z.J. & Lai W.M. (2012) Streptococcus agalactiae, an emerging pathogen for cultured ya-fish, Schizothorax prenanti, in China. Transboundary and Emerging Diseases 59, 369–375. Gudkovs N.. (1988) Fish immunology, In: Fish diseases: refresher course for veterinarians. Proc 106, Post Graduate Committee in Veterinary Science, University of Sydney, pp. 531–544. Iguchi K.I., Ogawa K., Nagae M. & Ito F. (2003) The influence of rearing density on stress response and disease susceptibility of ayu (Plecoglossus altivelis). Aquaculture 220, 515–523. Imperi M., Pataracchia M., Alfarone G., Baldassarri L., Orefici G. & Creti R. (2010) A multiplex PCR assay for the direct identification of the capsular type (Ia to IX) of Streptococcus agalactiae. Journal of Microbiology Methods 80, 212–214. Kosoff R.E., Chen C.Y., Wooster G.A., Getchell R.G., Bowser P.R., Clifford A., Craig J.L., Lim P., Wetzlich S.E., Craigmill A.L. & Tell L.A. (2009) Florfenicol residues in three species of fish after 10-day oral dosing in feed. Journal of Aquatic Animal Health 21, 8–13. Maruvada R., Zhu L., Pearce D., Sapirstein A. & Kim K.S. (2011) Host cytosolic phospholipase A2α contributes to Group B Streptococcus penetration of the blood-brain barrier. Infection and Immunity 79, 4088–4093. Mian G.F., Godoy D.T., Leal C.A.G., Yuhara T.Y., Costa G.M. & Figueiredo H.C.P. (2009) Aspects of the natural history and virulence of S. agalactiae infection in Nile tilapia. Veterinary Microbiology 136, 180–183. Pasnik D.J., Evans J.J. & Klesius P.H. (2006) Passive immunization of Nile tilapia (Oreochromis niloticus) provides significant protection against Streptococcus agalactiae. Fish & Shellfish Immunology 21, 365–371. Poyart C., Tazi A., Reglier-Poupet H., Billoet A., Tavares N., Raymond J. & Trieu-Cuot P. (2007) Multiplex PCR assay for rapid and accurate capsular typing of group B streptococci. Journal of Clinical Microbiology 45, 1985–1988. Pulkkinen K., Suomalainen L.R., Read A.F., Ebert D., Rintamaki P. & Valtonen E.T. (2010) Intensive fish farming and the evolution of pathogen virulence: the case of columnaris disease in Finland. Proceedings. Biological sciences/The Royal Society 277, 593–600. Robinson J.A. & Meyer F.P. (1966) Streptococcal fish pathogen. Journal of Bacteriology 92, 512. Slotved H.C., Kong F., Lambertsen L., Sauer S. & Gilbert G.L. (2007) Serotype IX, a Proposed New Streptococcus agalactiae Serotype. Journal of Clinical Microbiology 45, 2929–2936. Suanyuk N., Kong F., Ko D., Gilbert G.L. & Supamattaya K. (2008) Occurrence of rare genotypes of Streptococcus agalactiae in cultured red tilapia Oreochromis sp. and Nile tilapia O. niloticus in Thailand—Relationship to human isolates? Aquaculture 284, 35–40. Suomalainen L.R., Tiirola M.A. & Valtonen E.T. (2005) Influence of rearing conditions on Flavobacterium columnare infection of rainbow trout, Oncorhynchus mykiss (Walbaum). Journal of Fish Diseases 28, 271–277. Vandamme P., Devriese L.A., Pot B., Kersters K. & Melin P. (1997) Streptococcus difficile is a nonhemolytic Group B, type Ib streptococcus. International Journal of Systematic Bacteriology 47, 81–85. Ye X., Li J., Lu M., Deng G., Jiang X., Tian Y., Quan Y. & Jian Q. (2011) Identification and molecular typing of Streptococcus agalactiae isolated from pond-cultured tilapia in China. Fisheries Science 77, 623–632. Citing Literature Volume37, Issue12December 2014Pages 1067-1072 ReferencesRelatedInformation

Journal of Fish DiseasesVolume 37, Issue 8 p. 757-763 Short Communication Chronic streptococcosis in Nile tilapia, Oreochromis niloticus (L.), caused by Streptococcus agalactiae Y W Li, Y W Li Key Laboratory for Aquatic Products Safety Department of the Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, ChinaSearch for more papers by this authorL Liu, L Liu Key Laboratory for Aquatic Products Safety Department of the Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, ChinaSearch for more papers by this authorP R Huang, P R Huang College of Veterinary Medicine, Hunan Agricultural University, Changsha, Hunan, ChinaSearch for more papers by this authorW Fang, W Fang Guangdong Provincial Aquatic Animal Epidemic Disease Prevention and Control Center, Guangzhou, Guangdong, ChinaSearch for more papers by this authorZ P Luo, Z P Luo Aquaculture Technology Service Station of Zhuhai, Zhuhai, Guangdong, ChinaSearch for more papers by this authorH L Peng, H L Peng Guangdong Provincial Aquatic Animal Epidemic Disease Prevention and Control Center, Guangzhou, Guangdong, ChinaSearch for more papers by this authorY X Wang, Y X Wang Guangdong Provincial Aquatic Animal Epidemic Disease Prevention and Control Center, Guangzhou, Guangdong, ChinaSearch for more papers by this authorA X Li, Corresponding Author A X Li Key Laboratory for Aquatic Products Safety Department of the Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China Correspondence A X Li, Key Laboratory for Aquatic Products Safety Department of the Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, 135 Xingang West Street, Haizhu District, Guangzhou 510275, Guangdong Province, China (e-mail:lianxing@mail.sysu.edu.cn)Search for more papers by this author Y W Li, Y W Li Key Laboratory for Aquatic Products Safety Department of the Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, ChinaSearch for more papers by this authorL Liu, L Liu Key Laboratory for Aquatic Products Safety Department of the Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, ChinaSearch for more papers by this authorP R Huang, P R Huang College of Veterinary Medicine, Hunan Agricultural University, Changsha, Hunan, ChinaSearch for more papers by this authorW Fang, W Fang Guangdong Provincial Aquatic Animal Epidemic Disease Prevention and Control Center, Guangzhou, Guangdong, ChinaSearch for more papers by this authorZ P Luo, Z P Luo Aquaculture Technology Service Station of Zhuhai, Zhuhai, Guangdong, ChinaSearch for more papers by this authorH L Peng, H L Peng Guangdong Provincial Aquatic Animal Epidemic Disease Prevention and Control Center, Guangzhou, Guangdong, ChinaSearch for more papers by this authorY X Wang, Y X Wang Guangdong Provincial Aquatic Animal Epidemic Disease Prevention and Control Center, Guangzhou, Guangdong, ChinaSearch for more papers by this authorA X Li, Corresponding Author A X Li Key Laboratory for Aquatic Products Safety Department of the Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China Correspondence A X Li, Key Laboratory for Aquatic Products Safety Department of the Ministry of Education/State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, 135 Xingang West Street, Haizhu District, Guangzhou 510275, Guangdong Province, China (e-mail:lianxing@mail.sysu.edu.cn)Search for more papers by this author First published: 17 August 2013 https://doi.org/10.1111/jfd.12146Citations: 46Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume37, Issue8August 2014Pages 757-763 RelatedInformation