“Changeable” Virus

Now we understand that the virus of flu “A” is the most insidious. It is able to change and causes mass epidemics on the planet. In the world there are many laboratories with an arsenal of the vaccines against flu developed for each serotype of drugs, but for flu “A” this arsenal is useless.

Almost every year there is flu epidemic. This virus took a special place among the viruses possessing ability to change. Changes usually happen in surface proteins of a virus which are recognized by protective system of the person and therefore immunity which was acquired after contact to one of flu types, doesn’t see the changes which happened in structure of a new virus.

Property thanks to which the virus is able to change is called antigenic change. Sometimes, it happens that changes of structure of a virus become essential, i.e. there is an antigenic shift. It is promoted with that fact that flu affects not only people but also birds and animals. Therefore it may happen that in one individual two or several kinds of viruses will meet. In this case they can exchange the whole genes. Such situation results in emergence of a new strain having even larger aggression than an initial virus. As result of such exchanges there is an emergence of a pandemic of Asian flu in 1957, Hong Kong in 1969 and H1N1pandemic nowadays. The originator of the most terrible pandemic of the twentieth century (Spanish influenza) developed due to antigenic drifting of a bird’s virus which caused catastrophic epidemic.

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