Reactogenicity

Ability to cause an immunological reaction

Reassortment

The recombination or mixing of the genetic material of viruses; may occur when two different influenza virus strains infect the same cell, resulting in the formation of a new influenza virus strain

Recombinant

Produced by genetic engineering

Recombination

The process by which DNA is broken and genetic material is exchanged through the crossover of DNA between maternal and paternal chromosomes. This can result in offspring having different combinations of genes than their parents.

Retrovirus

A type of virus that uses RNA as its genetic material (rather than DNA). Examples include HIV and HTLV.

RNA

Ribo nucleic acid, a chemical structure that is related to DNA, but has only one strand and a somewhat different chemical composition. RNA performs a variety of functions in the cell and can act as a messenger to carry the genetic code from the DNA to other parts of the cell. RNA can also serve as the genetic material of some viruses.