Development of a single-dose recombinant CAMP factor entrapping poly(lactide-co-glycolide) microspheres-based vaccine against Streptococcus agalactiae.
Streptococcus agalactiae is an important contagious bovine mastitis pathogen. Although it is well controlled and even eradicated in most Northern European and North American dairy herds, the prevalence of this pathogen remains very high in China. However, research on development of a vaccine against S. agalactiae mastitis is scarce. The aims of the present study were to: (1) develop a single-dose vaccine against S. agalactiae based on poly(lactic-co-glycolic acid) (PLGA) microspheres (MS) encapsulated CAMP factor, a conserved virulent protein encoded by S. agalactiae's cfb gene; and (2) evaluate its immunogenicity and protective efficacy in a mouse model. The cfb gene was cloned and expressed in a recombinant Escherichia coli strain Trans1-T1. The CAMP factor was tested to determine a safe dose range and then encapsulated in MS of PLGA (50:50) to assess its release pattern in vitro and immune reaction in vivo. Furthermore, a mouse model and a histopathological assay were developed to evaluate bacterial burden and vaccine efficacy. In the low dosage range (<100μg), CAMP factor had no obvious toxicity in mice. The release pattern in vitro was characterized by an initial burst release (44%), followed by a sustained and slower release over 7wk. In mice immunized with either pure CAMP factor protein or PLGA-CAMP, increased antibody titers were detected in the first 2wk, whereas only PLGA-CAMP immunization induced a sustained increase of antibody titers. In mice vaccinated with PLGA-CAMP, mortality and bacteria counts were lower (compared to a control group) after S. agalactiae challenge. Additionally, no pathological lesions were detected in the vaccinated group. Therefore, PLGA-CAMP conferred protective efficacy against S. agalactiae in our mouse model, indicating its potential as a vaccine against S. agalactiae mastitis. Furthermore, the slow-release kinetics of PLGA MS warranted optimism for development of a single-dose vaccine.
Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, PR China.
Gang
G
Liu
Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, PR China.
Jinhua
J
Yin
Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
Herman W
HW
Barkema
Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
Liben
L
Chen
Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, PR China.
Muhammad
M
Shahid
MTA-SZIE Large Animal Research Group, Üllő - Dóra Major, H-2225, Hungary.
Otto
O
Szenci
Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
Jeroen
J
De Buck
Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
John P
JP
Kastelic
Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, PR China. Electronic address: hanbo@cau.edu.cn.
Bo
B
Han
D000818:Animals; D058491:Bacterial Load; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology*; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology / Q000382:microbiology / Q000517:prevention & control*; D002681:China / Q000453:epidemiology; D004195:Disease Models, Animal; D005260:Female; D006460:Hemolysin Proteins / Q000235:genetics / Q000276:immunology*; D056724:Immunity, Humoral; D007700:Kinetics; D019344:Lactic Acid; D008413:Mastitis / Q000453:epidemiology / Q000382:microbiology; D051379:Mice; D008863:Microspheres; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D013290:Streptococcal Infections / Q000276:immunology / Q000517:prevention & control* / Q000662:veterinary; D022541:Streptococcal Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D013292:Streptococcus agalactiae / Q000276:immunology*; D014611:Vaccination
D001426:Bacterial Proteins; C039092:CAMP protein, Streptococcus; D006460:Hemolysin Proteins; D022541:Streptococcal Vaccines; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid
Mastitis; PLGA; Single dose; Streptococcus agalactiae; Vaccine