why do some vaccines protect against all isotopes of a virus, and others only protect against one?

Answer 1

Some Vaccines use attenuated virus, those that can't cause disease, some use the toxin the virus releases- it's outer membrane, and others vaccines use an exact replica of the virus but at a low dose. The attenuated virus vaccine may Target the mode of transmission the virus uses, and all similar viruses that use that path, one would be immune to. The Toxin one, whatever virus that has the same outer membrane structure, it would work for, but the low dose one- it would only protect against that specific virus. There are many more reasons why, it all depends on which way the vaccine uses to allow your body to recognize and store your B antibodies to defend against the virus in the future.

Answer 2

Viruses are obligate intracellular parasites and therefore have to enters cells to survive. The main aim of a vaccine is to produce antibodies that prevent the virus from entering a cell. These are called neutralizing antibodies. The way to do this is to block specific sites of the virus known as glycoproteins that interacts with cellular receptors and this prevents viral entry. In a live vaccine with a whole virus, antibodies are produced against the glycoproteins and other parts of the viurs such as its core but the main ones are those agains the glycoproteins.

However, many viruses have alot of serotypes, or different surface glycoproteins. For example the cold virus (rhinovirus) has 100 or more serotypes. There fore it is impossible to produce a vaccine for all the serotypes. The influenza virus has many strains. The two main glycoproteins are H (haemagglutinin) and N(neuramindase) There are 16H protein types and 9 N proteins. So the virus has differnt combinations of this such as H1N6, H1N5. When this virus infects a cell, it can exchange genes for the H and N and produce a different combination that is more pathogenic. Therefore it is not possible to produce a vaccine for all the strain.

Answer 3

depends on whether the vaccine is against the core, the protein coat, the genetic material (RNA or DNA) or multivalent. Because many viruses share antigenic determinants, its possible to have a vaccine against several isotypes.