Yellow fever vaccine: direct challenge of monkeys given graded doses of 17D vaccine.

In rhesus monkeys a wide dosage range of 17D yellow fever (YF) vaccine extending to a level even below that recommended for vaccination of man elicited an immune response providing solid protection to challenge with virulent YF virus. Forty-three of 45 monkeys vaccinated with 10(2.3) or greater weanling mouse mean lethal doses of 17D vaccine were resistant to challenge 20 weeks later with virulent Asibi strain YF virus.

Problems in the laboratory isolation of simian hemorrhagic fever viruses and isolatse metaboli enterobacteriaceae classificat enterobacteriaceae enzymology hydrogen peroxide metaboli enterobacteriaceae metaboliion of the agent responsible for the Sussex-69 epizootic.

At least six epizootics of simian hemorrhagic fever have occurred at four different primate centers. Although these diseases could easily be transmitted to other monkeys of the Macaca species, difficulty has been encountered in isolating the causative virus in cell culture. The results of this study have shown that the isolation of simian hemorrhagic fever virus strains in cell culture is dependent upon the use of a susceptible MA-104 cell strain and that the ability of such strains to support the replication of these viral agents may vary.

Identification and quantitation of the components of polyvalent inactivated influenza virus vaccines by immunodiffusion.

One of the basic problems in the standardization of inactivated polyvalent influenza virus vaccines has been the determination of the relative potency of the individual strain components. The chicken cell agglutination test measures reliably the total hemagglutinin content of these vaccines. With immunodiffusion techniques, it is now possible to quantitate each strain component of polyvalent vaccines.

Yellow fever vaccine. V. Antibody response in maonkeys inoculated with graded doses of the 17D vaccine.

A dosage equal to or greater than approximately 3.4 Dex (decimal exponent, log(10)) weanling mouse intracerebral 50% lethal dose (LD(50)) was sufficient to elicit a yellow fever antibody response, as determined by the plaque neutralization (PN) test, in better than 90% of vaccinated rhesus monkeys. Lower dosages were progressively less effective in terms of PN titers and the PN and hemagglutination-inhibition serological conversion rates observed.

Growth of respiratory syncytial virus in suspension cell culture.

Respiratory syncytial virus, Burnett strain, adsorbed efficiently and grew to high titers in suspension cultures of HEp-2 and MA-160 cells. Our results compared favorably with previous experience with the growth of respiratory syncytial virus in monolayer cell cultures. The use of suspension cell cultures provides a convenient and simple procedure for producing high-titering respiratory syncytial virus pools.

Intracerebral inoculation of rhesus monkeys with a strain of measles virus isolated from a case of subacute sclerosing panencephalitis.

Measles virus isolated from the brain of a patient with subacute sclerosing panencephalitis was injected intracerebrally (ic) into 34 rhesus monkeys. Groups of these animals were injected with measles antigen in Freund's complete adjuvant or treated by schedules used for suppression of the general or cell-mediated immune responsiveness. In another group of animals, experimental allergic encephalitis was induced parallel with measles infection.