PCR-Sequencing for Detection of Human Cytomegalovirus Mutations Conferring Antiviral Resistance
Antiviral resistant strains will emerge in at least 10% of patients receiving long-term antiviral therapy for the prevention or treatment of cytomegalovirus (CMV) infection and disease. Prophylaxis therapy with the antiviral agent valganciclovir (the oral pro-drug of ganciclovir) is becoming a common strategy for the prevention of CMV infection in immunocompromised transplant recipients, and accordingly, requests for CMV antiviral resistance testing are also increasing. The antiviral agents cidofovir and foscarnet are also used against ongoing CMV infection and disease when ganciclovir or valganciclovir therapy has failed, but resistance to these compounds can also develop. The most accurate, sensitive and comprehensive approach for identification of antiviral resistant CMV strains is PCR-sequencing, where segments of the CMV UL97 and UL54 genes are amplified by nested PCR and the PCR products sequenced [1, 2]. Mutations that confer antiviral resistance to CMV strains occur in specific regions of UL97 and UL54, and therefore only specific segments of these genes (one segment for UL97 and two for UL54) need to be amplified and sequenced, increasing the overall sensitivity and specificity of the assay. In combination, sequencing of these three PCR products allows the identification of all mutations known to confer resistance to ganciclovir and valganciclovir, as well as foscarnet and cidofovir, including DNA polymerase mutations that can confer cross-resistance to two or more of these compounds. This information is highly valuable to clinicians trying to determine a course of action where CMV-positive patients fail to respond to the antiviral agent they have been administered.
KeywordsAntiviral Agent UL54 Gene Antiviral Resistance Prophylaxis Therapy UL54 Mutation
- 3.Iwasenko JM, Scott GM, Rawlinson WD et al (2009) Successful valganciclovir treatment of post-transplant cytomegalovirus infection in the presence of UL97 mutation N597D. J Med Virol 81(3):510–807Google Scholar