Two glycoproteins jut out from the surface of the influenza virus: hemagglutinin (HA) and neuraminidase (NA). Both of these antigenic surface proteins play key roles in viral infection and dissemination. Influenza A and B can be differentiated by the protein forming the membrane spanning channel of each type of virus. In influenza A, the M 2 protein is present and is the target for older antivirals, the M 2 inhibitors. M 2 protein acts as an ion channel extending through the viral envelope and has an important role to play in the penetration and release of viral RNA into the host cell. Influenza B viruses contain a different protein and are therefore not sensitive to this drug class. Slide 21 Lecture Notes
What are pandemics? Pandemics are when a new influenza A emerges to which most or many of the population have no immunity. The result usually from an animal influenza combining some of its genes with a human influenza. To be a pandemic strain an influenza A virus needs to have three or four characteristics. They need to be able to infect humans, to cause disease in humans and to spread from human to human quite easily. An additional criteria that is often applied is that many or most of the population should be non-immune to the new virus. Note this animated slide was first developed by the National Institute of Infectious Disease in Japan and we are grateful to them and especially Masato Tashiro for letting us use it.
RIESGOS BIOLÓGICOS EMERGENTES, UNA AMENAZA PARA LA SALUD PÚBLICA Juan José Badiola Diez Catedrático de la la Universidad de Zaragoza Presidente del Consejo General de Colegios de Veterinarios de España
Pandemias de Gripe 1889 Gripe rusa H2N2 1957 Gripe asiatica H2N2 1968 Gripe de Hong Kong H3N2 1900 Gripe Hong Kong antigua H3N8 1918 Gripe española H1N1 2009 Gripe A H1N1 Subtipos virales registrados Reproduced and adapted (2009) with permission of Dr Masato Tashiro , Director, Center for Influenza Virus Research, National Institute of Infectious Diseases (NIID), Japan. Animated slide: Press space bar H7 H5 H9 * 1980 1997 Nuevos virus influenza aviares registrados 1996 2002 1999 2 003 1955 1965 1975 1985 1995 2005 H1N1 H2N2 H2N2 H3N2 H3N8 1915 1925 1955 1965 1975 1985 1995 2005 1895 1905 2010 2015 H1N1 H1N1
PANDEMIAS DE GRIPE DEL SIGLO XX Fuente: CDC IMPACTO EN LA POBLACIÓN CARACTERÍSTICAS Gripe española 1918-1919. H1N1 40 millones de muertos Tasa de ataque: 25-30% Letalidad del 2,5% Adultos jóvenes(15-35) Gripe asiática 1957-1958. H2N2 2 millones de muertos Niños y ancianos Gripe de Hong Kong 1968-1969. H3N2 1 millón de muertos Tasa de ataque:25-30% Niños y ancianos Gripe rusa 1977-1978. H1N1 Escasa mortalidad Jóvenes < 20 años