PubMed · 7691705
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D Moradpour, J R Wands, M Melegari. 1993. Chasing the escape mutant.. https://doi.org/10.1002/hep.1840180438
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Plants and animals detect biomolecules termed microbe-associated molecular patterns (MAMPs) and induce immunity. Agricultural production is severely impacted by pathogens which can be controlled by transferring immune receptors. However, most studies use a single MAMP epitope and the impact of diverse multicopy MAMPs on immune induction is unknown. Here, we characterized the epitope landscape from five proteinaceous MAMPs across 4,228 plant-associated bacterial genomes. Despite the diversity sampled, natural variation was constrained and experimentally testable. Immune perception in both Arabidopsis and tomato depended on both epitope sequence and copy number variation. For example, Elongation Factor Tu is predominantly single copy, and 92% of its epitopes are immunogenic. Conversely, 99.9% of bacterial genomes contain multiple cold shock proteins, and 46% carry a nonimmunogenic form. We uncovered a mechanism for immune evasion, intrabacterial antagonism, where a nonimmunogenic cold shock protein blocks perception of immunogenic forms encoded in the same genome. These data will lay the foundation for immune receptor deployment and engineering based on natural variation.
Growth hormone (GH) has been available for therapeutic use for more than 30 years, but there is still considerable debate about the best way to diagnose GH deficiency. This can be attributed to the existence of a variable degree of GH insufficiency in most cases and the fact that assays vary considerably between laboratories in terms of sensitivity and epitope specificity. These difficulties are compounded by the episodic nature of GH secretion and our reliance on a variety of provocative tests. A workshop and consensus report held in Portland, Oregon, in 1995 highlighted these issues and suggested a rational diagnostic approach that emphasizes good auxologic evidence, followed by assays of insulin-like growth factor I and insulin-like growth factor binding protein 3 to identify abnormalities in the GH axis. Actual assays of GH, during some provocative tests, are relegated to confirming that an identified abnormality in the GH-insulin-like growth factor axis is related to GH insufficiency rather than to GH resistance.
Considerable evidence suggests that immune mechanisms are involved in the pathogenesis of both hepatitis B and C. Both CD4+ and CD8+ T cell responses to viral antigens are important mechanisms that may be responsible for the hepatocyte damage in hepatitis B and C. CD4+ T cell proliferative responses to hepatitis B core antigen (HBcAg) in terms of stimulation index are correlated with hepatitis activity. These responses can be demonstrated in both adult and paediatric patients, and are more vigorous in patients with acute self-limited hepatitis B than in patients with chronic hepatitis B. Patients with hepatitis C also had a significant CD4+ T cell response to hepatitis C virus (HCV) antigens. These responses are also vigorous in acute hepatitis C with recovery than in those cases that evolve to chronic hepatitis C. In terms of human leucocyte antigen (HLA) class I-restricted, CD8+ cytotoxic T lymphocyte (CTL) response, antigenic peptides derived from HBcAg, hepatitis B surface antigen (HBsAg), and polymerase have been demonstrated as the targets for CTL recognition in hepatitis B patients. Multiple CTL epitopes within both HBsAg and HBcAg can be detected by sensitizing target cells with synthetic peptides. Similar to hepatitis B virus (HBV) infection, multispecific, HCV-specific CTL responses can coexist with an extensive quasispecies of viral variants. The mechanisms of viral persistence in both hepatitis B and C are not yet clarified.