Development of a colloidal gold immunochromatographic strip for rapid detection of Streptococcus agalactiae in tilapia

• Published in: Biosensors & bioelectronics Vol. 91; pp. 66 - 69
• Main Authors: Wen-de, Wu, Min, Li, Ming, Chen, Li-ping, Li, Rui, Wang, Hai-lan, Chen, Fu-Yan, Chen, Qiang, Mi, Wan-wen, Liang, Han-zhong, Chen
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15.05.2017
• Subjects: Animals; Antibodies, Bacterial - chemistry; Antibodies, Monoclonal - chemistry; Biosensing Techniques - instrumentation; Colloidal gold; Equipment Design; Female; Fish Diseases - diagnosis; Fish Diseases - microbiology; Gold Colloid - chemistry; Immunochromatographic strip; Immunochromatography - instrumentation; Immunoconjugates - chemistry; Mice; Mice, Inbred BALB C; Monoclonal antibody; Reagent Strips - analysis; Sensitivity and Specificity; Streptococcal Infections - diagnosis; Streptococcal Infections - microbiology; Streptococcal Infections - veterinary; Streptococcus agalactiae; Streptococcus agalactiae - isolation & purification; Tilapia; Tilapia - microbiology; Immunochromatographic strip; Tilapia; Monoclonal antibody; Colloidal gold; Streptococcus agalactiae
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2016.11.038

A colloidal gold immunochromatographic strip was developed for rapid detection of Streptococcus agalactiae (S. agalactiae) infection in tilapia. The monoclonal antibodies (mAb) 4C12 and 3A9 were used to target S. agalactiae as colloidal gold-mAb conjugate and captured antibody, respectively. The colloidal gold immunochromatographic strip was assembled via routine procedures. Optimal pH and minimum antibody levels in the reaction system for gold colloidal-mAb 4C12 conjugation were pH 7.4 and 18μg/mL, respectively. Optimal concentrations of the captured antibody 3A9 and goat anti-mouse antibody were 0.6mg/mL and 2mg/mL, respectively. The sensitivity of the strip for detecting S. agalactiae was 1.5×105 colony forming units (CFU). No cross-reaction was observed with other commonly encountered bacteria, including Pseudomonas fluorescens, Aeromonas hydrophila, Vibrio anguillarum and Streptococcus iniae. The assay time for S. agalactiae was less than 15min. Tilapia samples artificially infected with S. agalactiae were tested using the newly developed strip. The results indicated that blood, brain, kidney, spleen, metanephros and intestine specimens of infected fish can be used for S. agalactiae detection. The validity of the strip was maintained for 6 months at 4°C. These findings suggested that the immunochromatographic strip was effective for spot and rapid detection of S. agalactiae infected tilapia. •The strip was made of mono-antibody to detect the Streptococcus agalactiae.•The strip Applied to Tilapia fish farming.•Rapid diagnosed the disease of Streptococcus agalactiae.•The strip can test all kinds’ tissues samples.