Identification of a surface protein of Streptococcus suis and evaluation of its immunogenic and protective capacity in pigs.
A Streptococcus suis surface protein reacting with convalescent-phase sera from pigs clinically infected by S. suis type 2 was identified. The apparent 110-kDa protein, designated Sao, exhibits typical features of membrane-anchored surface proteins of gram-positive bacteria, such as a signal sequence and an LPVTG membrane anchor motif. In spite of high identity with the partially sequenced genomes of S. suis Canadian strain 89/1591 and European strain P1/7, Sao does not share significant homology with other known sequences. However, a conserved avirulence domain that is often found in plant pathogens has been detected. Electron microscopy using an Sao-specific antiserum has confirmed the surface location of the Sao protein on S. suis. The Sao-specific antibody reacts with cell lysates of 28 of 33 S. suis serotypes and 25 of 26 serotype 2 isolates in immunoblots, suggesting its high conservation in S. suis species. The immunization of piglets with recombinant Sao elicits a significant humoral antibody response. However, the antibody response is not reflected in protection of pigs that are intratracheally challenged with a virulent strain in our conventional vaccination model.
Li
Yuanyi
Y
Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de Médecine Vétérinaire, Université de Montréal, C.P. 5000, St.-Hyacinthe, Québec J2S 7C6, Canada.
Martinez
Gabriela
G
Gottschalk
Marcelo
M
Lacouture
Sonia
S
Willson
Philip
P
Dubreuil
J Daniel
JD
Jacques
Mario
M
Harel
Josee
J
D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D000942:Antigens, Bacterial / Q000008:administration & dosage / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D000954:Antigens, Surface / Q000008:administration & dosage / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D001426:Bacterial Proteins / Q000008:administration & dosage / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D002473:Cell Wall / Q000737:chemistry* / Q000276:immunology; D008969:Molecular Sequence Data; D012703:Serotyping; D013290:Streptococcal Infections / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D017011:Streptococcus suis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D013552:Swine; D018418:Th2 Cells / Q000276:immunology / Q000382:microbiology
D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D000954:Antigens, Surface; D001426:Bacterial Proteins