Post-transcriptional regulation of MHC class II expression in human T cells.

Human T lymphocytes are among those cells which are cell surface class II- in the resting state, but can be induced to express class II following treatment with appropriate stimulators. Although resting T cells do not express detectable surface class II, cell surface class II can be detected on purified T cells as early as 30 min following stimulation with PHA and PMA, well before the initiation of DNA synthesis, and the percentage of positive cells gradually increases with time. One hypothesis explaining this very rapid surface expression of class II is that the genes can be regulated post-transcriptionally in T cells.

Involvement of an inducible factor in interferon-gamma-mediated accumulation of HLA gene transcripts.

Earlier studies with a cDNA clone (C5-4) complementary to an interferon (IFN)-gamma-inducible mRNA showed that in human fibroblasts (FS-4), IFN-gamma induced the transcription of the cognate gene, but it required new protein synthesis (Caplen and Gupta, J. Biol. Chem.

Differential regulation of a cellular gene by human interferon-gamma and interferon-alpha.

Two cDNA clones complementary to interferon (IFN)-gamma inducible mRNAs in human cells were isolated, and one of these, C5-4, was used for studying the regulation of its cognate mRNA by IFNs. C5-4 cDNA hybridized to a 2.2-kilobase mRNA that coded for a 42,000 Mr polypeptide in vitro.

Pathogenicity and immunogenicity of a mutagen-attenuated Rift Valley fever virus immunogen in pregnant ewes.

A mutagenized clone of Rift Valley fever virus (RVFV; MV P12) used in inoculation of 3 pregnant ewes was immunogenic, nonpathogenic, and nonabortogenic. In contrast, inoculation of a matched group of 3 pregnant ewes with parent RVFV induced clinical disease and abortions. Ewes given MV P12 delivered healthy lambs that had RVFV antibody titers of less than 1:10 at birth, increasing to greater than or equal to 1:80 after ingestion of colostrum.

Mutagen-directed attenuation of Rift Valley fever virus as a method for vaccine development.

Serial mutagenesis with 5-fluorouracil has been employed to derive an attenuated strain of Rift Valley fever virus for use as a live virus vaccine.