Abstract: A method of testing phenotypic drug susceptibility in an enveloped virus-infected mammalian individual by testing on an enzyme packed into an enveloped virus, such as HIV, recovered from a biological sample, such as blood or plasma, from said individual is described. The method comprises the steps of a) adding an enzyme inactivating agent to the sample for inactivating polymerase activity other than that present in the enveloped virion, b) removing the enzyme inactivating agent, enzyme activity blocking antibodies, endogenous enzyme activity inhibitors and antiviral drugs, c) lysing the virus particle to release the enzyme, d) recovering the concentrated purified viral enzyme, such as a HIV reverse transcriptase (RT), resulting from c) and determining the drug sensitivity profile of the individual from the recovered enzyme by using sensitive enzyme assays. The drug sensitivity profile may be used for selecting drug treatment therapy. A commercial package is included.

Abstract: A method of concentrating and recovering an enzyme activity from enveloped viruses present in a biological sample, is described. The method comprises contacting the biological sample in a first buffer solution with a virus-binding matrix, such as an anion exchanger matrix, to attach virus particles present in the sample to the matrix, washing the matrix carrying the virus particles with a second buffer solution to remove components interfering with viral enzyme activity, lysing the immobilized virus particles in a third buffer solution and recovering the concentrated viral enzyme activity from the third buffer solution. Additionally, a commercial package containing written and/or data carrier instructions for performing laboratory steps for concentration and recovery of an enzyme activity from enveloped viruses present in a biological sample and at least one component necessary for the assay, is disclosed.