Why can some viruses not be targeted by antibodies for destruction? Is this a limitation for developing an ELISA-based protocol for detecting the disease?

Viruses in the host body are constantly changing and mutating in the dynamics of the physical and functional forms. For each kind of mutation the host body develops new antibodies.

Some viruses mutate too quickly and they are not detected by the antibodies in the host for their destruction. This can be considered as limitation of ELISA. ELISA is enzyme linked immunosorbent assay. It is a plate based assay technique used for the purpose of quantification of antibodies.

The number of antibodies produce will be related to the number of viral cells present in the body of the host.