Clinical utility of PCR CMV testing in aqueous and peripheral blood in patients with CMV retinitis

S Sudharshan

Purpose: Pp65 antigenemia and quantitative PCR can misleadingly be lower in CMV retinitis(CMVR) than in CMV diseases of other organs. Localised CMV organ infections may give false negative results in blood. To comparatively analyse sensitivity of pp65antigenemia, qualitative and quantitative PCR performed on blood and aqueous of CMVR patients and their therapeutic correlation.

Methods: Peripheral blood sample and intraocular specimens of 20 CMVR patients seen between 2008-2010 were subjected to pp65 antigenemia, qualitative and quantitative PCR testing using mtrII region of human CMV and comparatively analysed.

Results: Group I-11 patients-both aqueous and peripheral blood samples, Group II-9 patients-blood alone. Group I-RT-PCR was positive in aqueous in all patients. Four were positive for qualitative mtrII PCR also. In blood, CMV was detected by both qualitative and quantitative PCR, quantitative PCR alone and RT-PCR in 2 patients each. Three others were negative for CMV in blood. Sensitivity of RT-PCR in aqueous-100% and 36.3% for nPCR. Sensitivity of qualitative PCR in blood-45% and 72.7% in aqueous. Group-II-eight patients showed positivity for pp65 antigenemia assay, qualitative and quantitative PCR. Sensitivity of RT-PCR was 100% in peripheral blood. Sensitivity of nPCR and pp65 antigenemia assay was 88.8%.

Conclusions: RT-PCR was found to be most useful. CMV may be confined to eye and found in relatively less numbers/absent in blood in some patients. This can help decide mode of treatment of CMVR(intravitreal and/or a combination with systemic anti-CMV therapy) as the case may be especially in resource constraints settings.