Type A, B & C vaccines

[juju]

Hello,

I am doing a project on Influenza vaccines. I would like to know where I can find why type A vaccines are so effective and why type B and C aren't?

Please write back as soon as possible.
Thank you!

[Willz]

Hi juju,

Are you looking for specific websites that talk about the different influenza vaccine types?
Basically, type A influenza is much more common than type B and type C. Type C is especially rare in humans; most of the different types of influenza that humans contract are type A, including several different kinds of human flu (H5N1, H1N2, etc.) and avian flu. This explains why type A vaccines are more effective than type B and type C vaccines, since the most common influenza type is type A.
Here are some more detailed information about the 3 different types of influenza:
http://en.wikipedia.org/wiki/Influenzavirus_A
http://en.wikipedia.org/wiki/Influenzavirus_B
http://en.wikipedia.org/wiki/Influenzavirus_c

Hope this helps!

[juju]

Hi,

I am doing a project on influenza viruses and vaccines. I would like to know how doctors or scientists know if the you have type A, B or C virus?

Please Write Back
Thank You!

[MelissaB]

Juju,

Please keep all your posts in a single thread--it will help the experts help you. In order to do this, click 'new post' when you look at the responses to your questions rather than clicking 'new thread'.

Most of the time, doctors do not even know if a sick person has influenza--if you look at the CDC website, you will see that a lot of the viruses isolated from sick people thought to have the flu are not actually influenza viruses. The only way a doctor knows for sure is to take a blood sample from a sick person, isolate the virus, and then sequence it. The DNA sequence of the virus will tell scientists whether it is influenza at all, and if it is whether it's in the A, B, or C genus.

[juju]

Also, when the virus reaches the lab how do scientists distinguish if the virus is type, A, B, or C?
And, how long would it take for scientists to know if the virus is type A, B, or C?


Thank You!
Please write back!

[donnahardy2]

Hi Juju,

Influenza viruses are typed based on their M, or matrix, antigen, and this is done using an immunoassay. There are variations in the methods used to test, but there are commercially available tests based on what is called a sandwich assay. An antibody to a specific type of influenza is coupled to a solid surface or bead, a sample is mixed with the antibody and any specific-type viruses will bind to the antibody; a detection antibody is then added that will bind to the virus, and then a label is added that will bind to the antibody. Since antibodies are available that only interact with one type of influenza antigen, the assay is very specific.

Here is an example of a test kit that is based on a fluorescent label:

http://www.bd.com/ds/productCenter/256020.asp

These assays are expensive and require specialized equipment.

Here are some other websites that describe the basis of typing and subtyping influenza viruses.

http://pathmicro.med.sc.edu/mhunt/flu.htm
http://www.medindia.net/patients/patien ... _virus.htm
http://pathmicro.med.sc.edu/mhunt/flu.htm

Let us know if you have any other questions.

Donna Hardy