Liposaccharides and Capsules of the HAP Group Bacteria

Fenwick, B. W.

doi:10.1007/978-1-4899-0978-7_7

Cited by 1 publication

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“…Antibodies against capsule, lipopolysaccharides and outer membrane proteins serve as opsonins, thereby enabling phagocytosis by neutrophils (Thwaits and Kadis, 1991; Byrd and Kadis, 1992), but do not destroy A. pleuropneumoniae cells by complement binding (Rycroft and Cullen, 1990). Although these antibodies provide only partial protection against challenge by homologous A. pleuropneumoniae serotypes and, particularly, by heterologous serotypes (Inzana et al, 1988, 1991, 1993; Jansen, 1994; Beaudet et al, 1994), respective antigens contribute to typical lesion formation (Fenwick and Osburn, 1986; Paradis et al, 1994; Fenwick, 1994). Non‐capsulated A. pleuropneumoniae mutants are not virulent, but are useful as vaccines in protecting against swine pleuropneumonia (Inzana, 1996).…”

Section: Introductionmentioning

confidence: 99%

Overcoming Immune Tolerance During Oral Vaccination Against Actinobacillus pleuropneumoniae

Silin

Lyubomska

2002

Journal of Veterinary Medicine, Series B

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In the preliminary study mice were vaccinated orally with Actinobacillus pleuropneumoniae microsphere oral vaccine. The lung and eye mucous membranes of these mice did not contain increased immunoglobulin A (IgA) following the initial oral vaccination, possibly through antibody persistence and the phenomenon of immune exclusion. A similar tendency was found for serum IgG. However, after the second vaccination, IgA still did not increase significantly, which could be attributed to immune suppression due to the possibility of the intestine inducing immune tolerance. Only the third vaccination overcame this effect and increased the level of IgA. In order to achieve a high systemic and local immune response this study attempted to overcome the initial tolerance to oral vaccination by using temporary immunosuppression, increasing antigen dose, and prolonging vaccine influence. Triamcinolone, used in the later productive phase of the immune response after the first and second vaccinations, but restricted in the inductive phase of the second and third vaccinations, could disable immune tolerance. Suppression of antibody production before the next induction of the immune response by an oral vaccine combined with suppression of cell-suppressor activity led to the creation of systemic immunity with the possibility of high levels of A. pleuropneumoniae growth inhibition. Increased antigen doses or durable consumption of antigen could overcome immune exclusion of antigen by primary antibodies. Even very low doses of vaccine (4.5 mg) could induce a primary immune response, and a dose increased by 10-fold for the second vaccination could overcome tolerance and maintain high systemic immunity. Chronic consumption of oral vaccine led to benefits in the quantity of local (not systemic) antibodies. The outcomes of the study can be adapted for practical oral immunization of pigs.

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