Serological Responses of Patas Monkeys (Erythrocebus patas) to Vaccination Against Cholera and Yellow Fever

Abstract

Gateff (1), after examining sera from a small number of persons in Africa, stated that cholera vaccination (CV) may lower the yellow fever (YF) antibody titers and vice versa. Nonhuman primates respond with antibody formation to most vaccines used in man. Patas monkeys (Erythrocebus patas) are especially useful in the study of immunologic responses to antigens prepared from vibrios, as well as from yellow fever virus (2). Therefore, this species was used to see whether or not antagonism between CV and yellow fever vaccine (YFV) occurs in primates other than man.

Patas monkeys. Patas monkeys of both sexes, weighing 4–8 kg and free from signs of disease as determined by clinical, hematological, urine, stool, clinical chemistry and blood culture examination, were used. Blood samples were collected before and periodically after inoculations. The sera were stored at —20° without a preservative.

Vibriocidal antibody titer (VA) determinations. Vibriocidal antibody titer was determined by technique of Watanabe et al. (3) using Vibrio cholerae Ogawa 41 strain. Only 3+ and 4+ reactions were recorded as positive.

Yellow fever neutralizing antibodies. The plaque-neutralization test of Spector and Tauraso (4, 5) was used with the 17D vaccine strain. The neutralizing titers of the sera were recorded in decimal exponents, log₁₀ (Dex) of the highest dilution (6).

All serologic tests were carried out in duplicate.

Vaccination procedure. Cholera vaccination consisted of the intramuscular injection of 4 × 10⁹ phenol-killed and phenol-preserved V. cholerae Ogawa 41 organisms; vaccination against yellow fever was by the im injection of 1/2 the adult human dose of the 17D vaccine. Groups of 4 patas monkeys each were vaccinated with YFV 8, 6, 4, and 2 weeks before, simultaneously with; and 2, 4, 6, and 8 weeks after the administration of cholera vaccine, respectively.