Patent ID: 6077661
Filing Date: 2000-06-20
Classification: C07K,C12N,C12Q

Abstract:
A method for quantitating an amount of a wild type virus present in a sample from a mammal, amphibian, reptile or bird, said method comprising the steps of:(a) adding to an aliquot of said sample, as an internal control, a composition comprising a specified amount of a genetically tagged virus containing a genetically tagged nucleic acid having a genetic tag sequence, said genetic tag sequence having a mutation in a region other than a conserved, non-coding region of said wild type virus, said mutation comprising a deletion, insertion or substitution, thereby providing a novel, engineered site having a sequence that does not occur in a genome contained in the sample at a position corresponding to the engineered site;(b) co-isolating said wild type nucleic acid and said genetically tagged nucleic acid, respectively, from said wild type virus and said genetically tagged virus in said sample;(c) amplifying in vitro said wild type nucleic acid and said genetically tagged nucleic acid from said sample to provide amplified wild type nucleic acid and amplified tagged nucleic acid;(d) quantitating the ratio of the amount of said amplified wild type nucleic acid to said amplified tagged nucleic acid provided in said amplifying step (c);(e) wherein the ratio of amplified wild type nucleic acid to genetically tagged nucleic acid, quantitated in step (d), is proportional to the ratio of said wild type virus to said genetically tagged virus in said sample, andwherein said genetically tagged nucleic acid comprises a genetic tag sequence of sufficient length that said wild type and genetically tagged nucleic acids can be quantitated after amplification, and wherein the genetic tag sequence does not prohibit the growth of said genetically tagged virus.