April 11, 2014

Dr. Kawaoka gave a talk at the Institut Pasteur as part of the 9th Louis Pasteur conference on Emerging Infectious Diseases. No title or abstract were provided. Lots of data were flashed up; not easy to keep up with the tempo.


• Started with pandemic 2009 influenza A virus (pH1N1) and selected escape mutants with polyclonal sera. Classic. There was little diversity and was disappointed.

• Took gene segment corresponding to amino acid residues 71-270 of the hemagglutinin (HA), performed error prone PCR, re-expressed as mutant library in H1N1 backbone by reverse genetics.

• Took 14 convalescent sera and isolated 50 escape mutants. Found 9 amino acid sites of variation.

• Factored in a few other sites (didn’t catch how) and ended up with 15 key sites in the HA sequence

• Performed saturation codon mutagenesis on these sites in the gene and ended up with 2 amino acid site, 3 site, 4 site and 5 site virus variants that were further refined by mutagenesis. 4 and 5 site mutants completely escaped vaccine-induced antibodies.

They worked hard to get a vaccine resistant virus. Apparently the work was performed at biosafety level 2 (BSL2).

April 10, 2014

Linster M, van Boheemen S, de Graaf M, Schrauwen EJ, Lexmond P, Mänz B, Bestebroer TM, Baumann J, van Riel D, Rimmelzwaan GF, Osterhaus AD, Matrosovich M, Fouchier RA, Herfst S.
Identification, characterization, and natural selection of mutations driving airborne transmission of A/H5N1 virus.
Cell. 2014 Apr 10;157(2):329-39. doi: 10.1016/j.cell.2014.02.040.