When more than one influenza A virus subtype is circulating in humans, as has been the case since 1977, there are several possible outcomes. The viruses might co-circulate, one virus might out-compete another, or co-infection of cells with two viruses can lead to the production of genetically distinct viruses by the process of reassortment of …
Pandemic H1N1 influenza virus outcompetes seasonal strains in ferrets Read More »
Of the many questions that I receive about influenza, one of the most common is “when will swine flu return to the US?”. In other words, when will the 2009 pandemic H1N1 strain, first recognized in humans in April 2009, emerge for the 2009-2010 influenza season? “Return” is probably not the correct word to use, …
The Advisory Committee on Immunization Practices (ACIP) has released its recommendations on the use of influenza A (H1N1) 2009 monovalent vaccine. Here is my summary of the salient points. The report begins with information on who is contracting pandemic 2009 H1N1 influenza. The median age of persons with laboratory-confirmed infections in the United States is …
There has been a great deal of discussion about the use of adjuvants to improve the immunogenicity of vaccines against the 2009 H1N1 pandemic influenza strain. What effect do these compounds have on the immune response? Adjuvants are compounds added to vaccines that stimulate the immune response. They are often used when the antigen is …
The second RNA segment of the influenza virus genome encodes the PB1 protein – part of the viral RNA polymerase – and, in some strains, a second protein called PB1-F2. The latter protein is believed to be an important determinant of influenza virus virulence. The absence of a full-length PB1-F2 protein has been suggested as …
Two different influenza vaccines will be available in the fall of 2009. One will be a trivalent preparation comprising seasonal influenza H3N2 and H1N1 strains, plus an influenza B virus strain. A monovalent vaccine will also be available against the 2009 pandemic H1N1 strain. Many readers of virology blog have asked why these four virus …
