Biomedical subjects
Publications and source records attributed to U Ray.
Mice infected with reovirus type 1 developed a mild thyroiditis characterized by focal destruction of acinar tissue, infiltration of inflammatory cells, and autoantibodies to thyroglobulin and microsomal antigens. Thyroid involvement appears to be part of a more generalized virus-induced polyendocrine disease.
Inoculation of suckling mice with coxsackievirus B4 (CB4) results in the death of a majority of the animals. In this study we selected antigenic variants of CB4 in the presence of neutralizing monoclonal antibodies and tested them to see whether they were attenuated. Antigenic variants selected with a single antibody showed little or no attenuation by producing a high mortality (60 to 100%). A double variant selected with two antibodies showed considerable attenuation by causing only 25% mortality. A triple variant selected with three antibodies was almost completely attenuated (killed only 5% of the animals). Polypeptides from these variants were tested for their ability to interact with the monoclonal antibodies used for their selection. These studies showed that resistance of variant virus to neutralization in general was due to the inability of the antibody to bind to the virus. However, one of the antibodies could bind but not neutralize the virus, perhaps due to an alteration in the epitope. It is concluded that selection of CB4 variants using more than one neutralizing monoclonal antibody can lead to attenuation of the virus.
A suppressor mutation of E. coli mut T has been isolated and mapped in the lue--ace(E/F) region.
Fv-1 gene-mediated host restriction of Friend leukemia virus replication was investigated in terms of coat protein synthesis. By using the assay of pseudotype formation with vesicular stomatitis virus. it was shown that under restricting growth conditions the availablity of leukemia virus coat protein for pseudotype formation was decreased. These studies appear to eliminate a pure assembly defect as the mechanism of Fv-1 host restriction.
When bacteriophage lambda DNA replication is blocked by mutation in phage genes O or P, the efficiency of lysogenization drops to a very low value unless high multiplicities of infecting phage are used. Our results show that even at high multiplicity, lambda O or P mutants cannot efficiently lysogenize some hosts that are defective in either DNA polymerase I or DNA ligase. Covalent closure of infecting DNA molecules, a preliminary step for insertion according to Campbell's model and an obvious candidate for this lysogenization defect, appears to occur normally under our conditions. In addition, prophage excision as measured by the frequency of curing O- and P- lysogens seemed normal when tested in the poll- strain. These results suggest that the Escherichia coli enzymes DNA polymerase I and ligase, and phage proteins O and P, are able to provide some complementary activity whose function is required specifically for prophage integration.