IPHY 4440 1st Edition Lecture 26Outline of Last Lecture I. Caused by Mycobacterium lepraeII. Two different forms of diseaseIII. Influenza Virus IV. 2 main types of influenza V. Influenza Attachment and Host Cell EntryVI. Replication Cycle of Influenza AOutline of Current Lecture II. Influenza Genome III. Antigenic DrifIV. Pandemic Flu TodayV. Vaccine Current LectureI. Influenza GenomeA. A shell of matrix proteins loosely contains RNA genome.RNA segments are coated with nucleocapsid proteins (NPs)B. H1N1 influenza Lots of strains -Three main groups: A, B, Ce.g. A = mostly H1, H2, H3 + N1 and N2H1N1 = 1918 pandemic (reappeared in 1977, 2009)H2N2 = 1957H3N2 = 1968 H5N1 = “bird flu”B. Antigenic Determinants/Virulence FactorsHemagglutinin: 16 typesC. Neuraminidase:- Cleaves surface receptors promoting release of viruses from cells- 9 typesWhat causes evolution of new flu viruses?- Primarily changes in NA and HAThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.II. Antigenic Drif"antigenic drif" = year to year minor variations (mutations) in the code for NA and HA "antigenic shif" = major changes in NA or HAMajor changes caused of deadly pandemics (e.g. 1918 and 1957)Possible genetic rearrangement among duck, swine and human flu viruses (usually inpigs as the “mixing vessel”)- Antigenic Drif year to year minor mutations in HA and NA genes - Antigenic Shif rearrangement of RNA segments due to multiple infections by different viral strains- More than one strain of flu infect a single cell (usually in pigs) at the same time Thus during assembly of the viral-RNA segments mixed and matched into new viruses- Major new antigenic presentation- Pigs can be infected with multiple influenza strains, pigs as “mixing vessels”III. Pandemic Flu TodayDespite..– Expanded global and national surveillance – Better healthcare, medicines, diagnostics– Greater vaccine manufacturing capacityNew risks:– Increased global travel and commerce– Greater population density– More elderly and immuno-suppressed– More daycare and nursing homesA. H5N1 “avian flu”, “bird flu”- 1st reported in Asia in 1997- Outbreak in Hong Kong killed 6 healthy adults- In response, the entire population of poultry in Hong Kong culled within 3 days (1.5 million chickens)How do you develop resistance to a given influenza strain?- production of antibodies against hemagglutinin and neuraminidaseIV. Vaccine -Made from killed viral strains - ‘best guess’ of main antigenic types - viruses grown in chicken eggs-Each year choose which variant of each subtype is the best to use for optimal protection-Usually 2 type A strains (H3N2, H1N1), 1 type B strain-Vaccine production takes a minimum of 6 monthsA. Treatmentamantadine; blocks viral uncoating inside cell- 92% of major flu strains are resistant Neuraminidase inhibitors (Tamiflu, Relenza) Prevents virion release Recent increases in
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