Attempts to Demonstrate Virus-Neutralizing Substances in Saliva and Serum from Mumps Immunes. ∗

Active immunity to experimental mumps parotitis in Macacus rhesus has been studied by Johnson and Good pasture, 1 with the following conclusions: “The only reliable experimental method at present of inducing active immunity to mumps in monkeys is by causing a unilateral or bilateral clinical or subclinical specific parotitis by intraparotid inoculation”. They failed, except rarely, to demonstate any passive immunity to mumps in monkeys previously injected with the serum of persons immune to this disease, or any marked virus-neutralizing action of human convalescent serum.

As a further step toward understanding the mechanism of active immunity to experimental mumps, the present study has been made concerning the virus-neutralizing properties of human and monkey saliva and of monkey serum.

For this purpose it was decided to inject a number of normal Macacus rhesus monkeys by the usual transductal route with variously treated mixtures of mumps virus (saline suspensions of infected glands) and saliva (or serum) from immune or normal animals and human beings. One parotid would receive the immune substance, the other the normal, and the presence or absence of virus-neutralizing substances would be shown by the presence or absence of or difference in the mumps “takes” on the 2 sides, with respect to time of onset and size of gland.

Several monkeys were actively immunized by unilateral of bilateral injections, into the parotid duct, of centrifuged saline suspensions of the parotid glands of monkeys in the active stage of experimental mumps. The virus used had been recently obtained from the saliva of a boy in the first day of clinical mumps, and had undergone several typical monkey passages, with characteristic clinical signs and gross and microscopic changes in the glands.

When the inoculated animal developed, on the 6th to 8th day, fever, swelling of the parotid gland or glands, with or without edema of the overlying tissues, and enlargement of the adjacent lymph-nodes, it was assumed, on the basis of the constantly positive results obtained by Johnson and Good pasture, that it had mumps, and would subsequently be immune.