Serologic profile of a cohort of pigs and antibody response to an autogenous vaccine for Actinobacillus suis

Abstract

-Actinobacillus suis is a commensal opportunistic pathogen in swine. However, in recent years, an increasing prevalence of clinical signs associated with A. suis has been observed in high health status herds in North America. The objectives of the study were to assess the kinetics of antibodies to A. suis in pigs from a herd showing clinical signs of A. suis infection and, to evaluate the antibody response in gilts following vaccination with an autogenous vaccine. An enzyme-linked immunosorbent assay (ELISA) using a saline extract of boiled-formalinized whole cells of a field strain as the coating antigen was standardized. This ELISA was used as a tool for monitoring, in a comparative way, the variations in A. suis antibody levels. The herd selected for the serologic profile was negative for Actinobacillus pleuropneumoniae infection and showed clinical signs of A. suis infection in 16 to 19-week-old pigs. A cohort of 20 pigs was blood sampled at 5, 8, 12, and 16 weeks of age. The lowest level of serum antibodies was observed between weeks 8 and 12, this probably corresponding to a decrease in maternal immunity. A marked increase in the antibody response was seen at 16-week of age, at the approximate time of onset of A. suis clinical signs in the herd. The evaluation of serum antibody responses to an autogenous vaccine revealed that the humoral immunity of gilts further increased following vaccination although the level of antibodies was already high prior to vaccination. The magnitude of the response to vaccination was higher when the level of antibodies was low prior to the first injection. The ELISA test seems to detect antibodies against the O-chain LPS. Actinobacillus suis / autogenous vaccine / ELISA / serologic profile / pigRésumé -Profil sérologique chez une cohorte de porcs et réponse humorale à un autovaccin pour Actinobacillus suis. Actinobacillus suis est généralement considéré comme un agent pathogène opportuniste chez le porc. Toutefois, en Amérique du Nord, une augmentation de la prévalence des signes cliniques associés à A. suis a été notée récemment dans des troupeaux de haut statut sanitaire. Les objectifs de cette étude étaient d'évaluer la cinétique des anticorps chez des porcs provenant Vet. Res. 32 (2001) 175-183 175

Three cases of Actinobacillus suis in eastern North Carolina

“…1-3,6-10, [12][13][14] It is a ubiquitous opportunistic pathogen and early colonizer of the tonsils and nasal cavity of healthy pigs. 2,3,5,[7][8][9][10][11][12][15][16][17][18] It can also be found in the vaginal mucosa of sows. 2,3,[8][9][10]12 Actinobacillus suis is believed to pass from sows to piglets.…”

“…7 Skin lesions similar in appearance to erysipelas, abortions, metritis, fever, and anorexia can be observed in this form. 2,3,7,9,11,16 Again, hemorrhages in multiple organs and fibrin can be seen during necropsy. 3,7 Differentials should include APP, GPS, and erysipelas.…”

Actinobacillus suis and Actinobacillus equuli, emergent pathogens of septic embolic nephritis, a new challenge for the swine industry

“…Actinobacillus suis has emerged as a new threat to swine health, particularly in high health status herds; and the occurrence of the disease in this group of pigs has been attributed to lack of herd immunity in these closed herds, but there is minimal information about the immunogenicity of A. suis (Yaeger 1996, MacInnes and Desrosiers 1999, Wilson and McOrist 2000, Lapointe et al 2001, Oliveira 2007. Actinobacillus suis is an early colonizer of the upper respiratory tract of swine and the nasopharynx and palatine tonsils are the main colonization sites (Ojha et al 2005).…”

“…Vaccination and serodiagnostic testing are complicated by the presence of multiple serotypes, and cross-reactive antigens (Rosendal and Mittal 1985, Fenwick et al 1996, MacInnes and Desrosiers 1999, Lapointe et al 2001, Oliveira 2007. Currently, no sero-diagnostic tests or vaccines are commercially available to help controlling A. suis infections .…”

“…Serologic profile could be used to determine the duration of passive immunity in a specific herd in order to help implementing the best vaccination strategy. The use of autogenous A. suis vaccine increased the specific humoral immunity in gilts (Lapointe et al 2001). Oliveira et al (2007) reported that A. suis affecting North American swine herds are highly clonal and this information may be important for the selection of vaccine strains.…”