Role of the amino acid mutations in the HA gene of H9N2 avian influenza virus under selective pressure in escape vaccine antibodies

It has been well-documented that some amino acid mutations in hemagglutinin (HA) of H9N2 avian influenza virus (H9N2 virus) alter the viral antigenicity, but little is reported about the role of antibody escape mutations in escape vaccine antibodies. In this study, we found that the evolution of F/98 strain in chicken embryos or chickens resulted in significant differences in immune escape, and identify the contribution of HA mutations to the antigenic variation and immune escape of H9N2 virus. Among amino acid mutations in the HA of the antigen variant viruses occurring in embryonated chicken eggs and/or chickens with or without the selection pressure of vaccine antibodies, the mutations, S145N, Q164L, A168T, A198V, M224K and Q234L, affect the antigen drift of H9N2 virus. Specially, the A198V mutation, located at the receptor-binding site on the head domain of HA, significantly contributed the antigenic variation of H9N2 virus. The mutation A198V or Q234L significantly improved the receptor binding activity, while S145N mutation decreased the receptor binding activity. Single S145N mutation could promote viral escape from polyclonal antibodies (pAbs) by preventing Ab binding physically, and single A198V mutation could promote viral escape from pAbs by enhancing the receptor binding activity. Additionally, either the mutation S145N or A198V did interfere with the immunogenicity of the inactivated vaccine, resulting in reduction of the protective efficiency of H9N2 inactivated vaccine, which contributed escape from the antibody-based immunity. Our findings provided an important reference for the accurate evaluation of the role of the amino acids mutation in HA affecting the antigenicity of H9N2 virus on immune escape, and delivered a new perspective for monitoring the adaptive evolution of H9N2 virus.ImportanceIn this study, the role of the HA mutations of H9N2 virus occurring with and without antibody selective pressure on escaping from the antibody-based immune response in host was analyzed. The results demonstrated that (i) the HA mutations S145N, Q164L, A168T, A198V, M224K, and Q234L occurring in the process of the adaptive evolution of H9N2 virus in embryonated chicken eggs and/or chickens could affect the antigenic variation of H9N2 virus. Among these mutations, the HA mutation A198V had the most significant effect on the antigenic variation; (ii) S145N mutation promoted viral escape from pAbs by preventing Abs binding physically; (iii) A198V mutation did promote viral escape from pAbs by enhancing the receptor binding activity; (iv) neither the HA mutation S145N or A198V interfered with the immunogenicity of the inactivated vaccine, resulting in reduction of the protective efficiency of H9N2 inactivated vaccine.

Chemical composition and biological effects of kratom (Mitragyna speciosa): In vitro studies with implications for efficacy and drug interactions

The safety and efficacy of kratom (Mitragyna speciosa) for treatment of pain is highly controversial. Kratom produces more than 40 structurally related alkaloids, but most studies have focused on just two of these, mitragynine and 7-hydroxymitragynine. Here, we profiled 53 commercial kratom products using untargeted LC–MS metabolomics, revealing two distinct chemotypes that contain different levels of the alkaloid speciofoline. Both chemotypes were confirmed with DNA barcoding to be M. speciosa. To evaluate the biological relevance of variable speciofoline levels in kratom, we compared the opioid receptor binding activity of speciofoline, mitragynine, and 7-hydroxymitragynine. Mitragynine and 7-hydroxymitragynine function as partial agonists of the human µ-opioid receptor, while speciofoline does not exhibit measurable binding affinity at the µ-, δ- or ƙ-opioid receptors. Importantly, mitragynine and 7-hydroxymitragynine demonstrate functional selectivity for G-protein signaling, with no measurable recruitment of β-arrestin. Overall, the study demonstrates the unique binding and functional profiles of the kratom alkaloids, suggesting potential utility for managing pain, but further studies are needed to follow up on these in vitro findings. All three kratom alkaloids tested inhibited select cytochrome P450 enzymes, suggesting a potential risk for adverse interactions when kratom is co-consumed with drugs metabolized by these enzymes.

ROLE OF SERIN/ THREONINE KINASE INHIBITOR IN THERAPY NON-ALCOHOLIC STEATOHEPATITIS AND ALCOHOLIC HEPATITIS

Liver fibrosis is a reversible response to a wound healing with marked accumulation of extracellular matrix which caused by injury to the liver. Liver fibrosis can be caused by various factors including alcohol and non-alcohol steatohepatitis. The process of fibrosis serves to localize the inflammation during chronic exposure. The hepatic stem cell (HSC) has a key role in the pathogenesis of liver fibrosis. The HSC activation is characterized by increased profibrogenic mediators including members of the TGF-? superfamily. In order to enable signal transduction, the mediator needs to bind to its receptors. The serine/ threonine kinase receptor is a receptor that binds to the TGF-? superfamily ligand, including TGF-?, BMP, activin and other mediators. The ligand receptor-binding activity will stimulate signal transduction that will translocate into the nucleus and phosphorylate various transcription factors that play a role in cell proliferation, differentiation, or apoptosis. There is currently no standard therapy for liver fibrosis. Based on the central role of the serine/ threonine kinase receptor in the pathogenesis of liver fibrosis, it is thought that the use of serine/ threonine kinase inhibitors is a promising therapy.