New flu strain 'has mutated, become more infectious'

[cHeroKee]

The Yomiuri Shimbun (http://www.yomiuri.co.jp/dy/national/200....)

The new strain of influenza appears to have mutated to become more infectious for humans, the online edition of science magazine Nature reported Monday, referencing research by a team including Prof. Yoshihiro Kawaoka of Tokyo University's Institute of Medical Science.

The surface of influenza virus particles are covered with thorn-shaped proteins called hemagglutinin (HA), which allows the virus to stick to human cells.

After analyzing multiple samples of the new flu virus, the team ascertained that in some cases the HA of the new H1N1 strain have mutated, allowing the strain to stick to human cells more easily.

According to Kawaoka, the same mutations have been found in HA of the H5N1 strain of influenza, the highly virulent bird flu, which kills about 60 percent of those it infects. Kawaoka said the virus is still in the process of mutating into a form even more infectious to humans.
(Jun. 16, 2009)


(http://www.yomiuri.co.jp/dy/national/20090616TDY03103.htm)

[cHeroKee]

Another report that in Hong Kong, a Mexiflu sequence was released that had a recombination event on the PB2 protein.

This mutation, seen before in H5N1 and the 1918 pandemic virus, supposedly allows influenza grow best at 33 C, the temp of the nose during the winter. The current circulating strain is mostly avian at this genetic point, which means it grows at avian temps of 44C.

Some believe the higher temp sequence is why it is spreading in summer.

I've always thought that theory bull, as 44C is 111.2 F.

33C is 91 degrees F, and is about right for nose temps, as the outside air cools down the nasal tissues below core body temperature.

37 is 98.6 F is the "normal" core body temp.

40 is 104 F

The only way this "higher temp" protein theory to be true is if the reproduction temperature growth chart has a large bulge to the right side of the peak optimal growth temperature.

[signseeker]

How would the "airborne" virulence be affected by outside temperature, if it is at all?