Viral Genetics

Recombination

Reassortment

Complementation

Phenotypic Mixing

A major determinant of viral tropism for the specific tissues of specific hosts is the extent to which the viral surface proteins can bind to complementary host cell plasmalemma receptors.

In the case of an enveloped virus, whether or not the virus can attach to a specific host cell generally depends on if a viral envelope glycoprotein with a high binding affinity for a host cell surface glycoprotein is present.

Eg. Influenza Virus

Mutations in viral encoded capsid proteins, RNA polymerases, endonucleases, or proteases could nonspecifically affect viral replication in the standard host cell but would be less likely to significantly after the range of host cell types that an enveloped RNA virus could successfully infect.

Virus ploidy

copies of RNA or DNA

basically, all RNA/DNA viruses contain haploid number (1 copy of RNA/DNA) except retroviruses which contain 2 copies of ssRNA

DNA viral genomes

Most DNA viruses - dsDNA except Parvovirus which is ssDNA

Most DNA viruses - linear DNA except

Papilloma (circular), Polyoma (circular) and Hepadna (partially circular)

RNA viral genomes

Most RNA viruses - ssRNA, except

Reovirus and Rotavirus which are dsRNA