Modified-live Vaccine Research Articles

Vitamin E is Immunostimulatory in Calves1,2

Thirty-two Holstein heifer calves, eight per group, were fed 0, 125, 250, or 500 IU/d of supplemental vitamin E/calf, from birth to 24 wk of age, in order to determine the effect on their immune responses. Overall mean lymphocyte blastogenic responses to various T-cell and B-cell mitogens were higher in supplemented calves than in control calves. Mean concentrations of cortisol in serum were lower in all supplemented calves than in control calves. Antibovine herpesvirus type 1 antibody titer (IgG) at 8 and 9 wk, in response to a commercial modified-live intranasal vaccine at 7 wk, was similar in all treatment groups. At 24 wk, in response to a booster at 21 wk, titer was higher in calves given 125 IU of vitamin E/d than in control calves. Based on the concentrations used, it is concluded that supplementation of conventional rations with 125 IU of vitamin E/d may maximize immune responses in calves and may be cost effective.

Repeated suppression of lymphocyte blastogenesis following vaccinations of CPV-immune dogs with modified-live CPV vaccines

A commercially available modified-live canine parvovirus (CPV) vaccine was evaluated for its immunosuppressive properties in eight random-bred dogs, all with circulatory antibody to CPV. Three of the eight dogs exhibited a significant decrease in lymphocyte blastogenesis after vaccine administration. In these dogs, this decrease in blastogenesis was of short duration and was consistently observed after repeated administrations of the vaccine. Neither gastroenteritis, fever nor leukopenia, signs indicative of virulent canine parvovirus infection, were detected in these animals. In addition, lymphocytes from these dogs lacked Ia antigen expression. This study demonstrated that the immunomodulating effects of ML-CPV is not observed in all animals yet is consistent in affected individuals.