Use of uniplex polymerase chain reaction & evaluation of multiplex PCR in the rapid diagnosis of viral retinitis.

BACKGROUND & OBJECTIVES Polymerase chain reaction (PCR) has been known to be a rapid and accurate diagnostic test for causative viruses of viral retinitis, but cost is the limiting factor. In the present study an attempt was made to standardize a multiplex PCR (mPCR) on intraocular specimens from patients with viral retinitis for the detection of one or more viruses [herpes simplex virus (HSV), varicella zoster virus (VZV) or cytomegalovirus (CMV)] in order to reduce the period of time required for uniplex polymerase chain reaction (uPCR). METHODS Using the uniplex PCR (uPCR) primers, a nested mPCR was developed and standardized for the simultaneous detection of HSV, VZV and CMV. mPCR and uPCRs were applied on 9 stored specimens and 38 prospective specimens obtained from patients with viral retinitis. RESULTS The specificity and sensitivity of the mPCR were concordant with that of uPCRs. Clinical specificity and sensitivity of mPCR was further confirmed by the detection of the same herpes viral DNA on the 9 stored specimens. Of the 38 specimens collected prospectively, mPCR detected HSV in 3 (7.9%), VZV in 9 (23.7%), CMV in 5 (13.2%) and both VZV and CMV in 2 (5.3%). Co-infections of two viruses were found in 7 (14.89%) of the 47 specimens. INTERPRETATION & CONCLUSION mPCR is a rapid, specific and sensitive diagnostic tool in viral retinitis. Compared to uPCR, mPCR is less time-consuming and cost effective.