Page 1386 - Veterinary Immunology, 10th Edition

glycopeptides or synthetic antigens can also enhance the
VetBooks.ir immunostimulating effects of MDP. MDP prolongs survival time

and decreases metastases in dogs with osteosarcoma.
Killed anaerobic corynebacteria, such as Propionibacterium acnes,

also promote antibody formation. These bacteria are phagocytosed
by macrophages and presumably stimulate cytokine synthesis
through TLRs. P. acnes has a complex activity since it stimulates
macrophages and the antibody response to thymus-dependent

antigens, but it has a variable effect on the response to thymus-
independent antigens. Killed P. acnes has been of benefit in the
treatment of staphylococcal pyoderma, malignant oral melanoma in
dogs, feline leukemia, and respiratory disease in horses. Other

bacterial components, such as staphylococcal cell walls (especially
staphylococcal phage lysate), some streptococcal components, and
components of Bordetella pertussis, Brucella abortus, Bacillus subtilis,
and Klebsiella pneumoniae, all have immunostimulating activity.

Immunomodulators have never been widely employed in
veterinary medicine, largely because of the biological variability of
the results obtained by their use. Parapoxvirus ovis (orf),
mycobacterial cell wall fractions, and killed Propionibacterium acnes

have, however, been employed in equine medicine. They improve
immune defenses nonspecifically and provide support for other
antimicrobial therapy. While they do not appear to protect against
respiratory infection, they may reduce respiratory disease severity,

reduce the frequency of complications, and accelerate recovery.

Complex Carbohydrates

Certain complex carbohydrates derived from yeasts, namely
zymosan, glucans, aminated polyglucose, and lentinans, can also

activate macrophages. These may function as adjuvants and
potentiate resistance to infectious agents. Fish such as trout, salmon,
and catfish appear to respond especially well to these

immunostimulants when incorporated in the diet. As a result,
immunostimulation by complex carbohydrates, especially glucans,
is routine in aquaculture.

Vitamins

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