title: Differential expression of gamma interferon mRNA induced by attenuated and virulent Mycobacterium tuberculosis in guinea pig cells after Mycobacterium bovis BCG vaccination.
abstract: To determine whether Mycobacterium bovis BCG vaccination would alter gamma interferon (IFN-gamma) mRNA expression in guinea pig cells exposed to Mycobacterium tuberculosis, we cloned a cDNA encoding guinea pig IFN-gamma from a spleen cell cDNA library. The cDNA is composed of 1,110 bp, with an open reading frame encoding a 166-amino-acid protein which shows 56 and 41% amino acid sequence homology to human and mouse IFN-gamma, respectively. Spleen or lymph node cells from naïve and BCG-vaccinated guinea pigs were stimulated with purified protein derivative (PPD) or M. tuberculosis H37Ra or H37Rv, and the total RNA was subjected to Northern blot analysis with a (32)P-labeled probe derived from the cDNA clone. Compared to the IFN-gamma mRNA expression in cells of naïve animals, that in spleen and lymph node cells exposed to various stimuli was enhanced after BCG vaccination. However, there was a significant reduction in IFN-gamma mRNA levels when cells were stimulated with a multiplicity of infection of greater than 1 virulent M. tuberculosis bacterium per 10 cells. The enhanced IFN-gamma mRNA response in BCG-vaccinated animals was associated with an increase in the proportions of CD4(+) T cells in the spleens, as determined by fluorescence-activated cell sorter analysis. Furthermore, the nonadherent population in the spleens enriched either by panning with anti-guinea pig immunoglobulin G-coated plates or by purification on nylon wool columns produced more IFN-gamma mRNA than whole spleen cells following stimulation with concanavalin A or PPD. This indicates that T cells are principally responsible for the upregulation of IFN-gamma mRNA expression following BCG vaccination. The mechanism by which virulent mycobacteria suppress IFN-gamma mRNA accumulation is currently under investigation.
authors.affiliation: Department of Medical Microbiology and Immunology, Texas A&M University System Health Science Center, College Station, Texas 77843, USA. ajeevan@medicine.tamu.edu
authors.forename: Amminikutty
authors.initials: A
authors.lastname: Jeevan
authors.forename: Teizo
authors.initials: T
authors.lastname: Yoshimura
authors.forename: Kyeong Eun
authors.initials: KE
authors.lastname: Lee
authors.forename: David N
authors.initials: DN
authors.lastname: McMurray
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001500:BCG Vaccine / Q000008:administration & dosage* / Q000276:immunology; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D003001:Cloning, Molecular; D018076:DNA, Complementary; D006168:Guinea Pigs; D007371:Interferon-gamma / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000276:immunology* / Q000472:pathogenicity*; D012333:RNA, Messenger / Q000378:metabolism*; D013154:Spleen / Q000166:cytology / Q000276:immunology; D014611:Vaccination
chemical_list: D001500:BCG Vaccine; D018076:DNA, Complementary; D012333:RNA, Messenger; D007371:Interferon-gamma