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KL Therese, B Mahalakshmi, HN Madhavan; Diagnostic Value of Nested Polymerase Chain Reaction (n PCR) for Detection of Toxoplasma Gondii in Aqueous Humor and Peripheral Blood Specimens of Clinically Suspected Cases of Toxoplasma Chorioretinitis . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4299.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To standardise and apply nested Polymerase Chain Reaction (n PCR) as a rapid and reliable laboratory diagnostic test to detect Toxoplasma gondii (T.gondii) in aqueous humor (AH) and peripheral blood samples of clinically suspected toxoplasma chorioretinitis patients. Methods: The nPCR using primers coding for B1 gene of T. gondii. was standardised for specificity using DNA of T.gondii , bacteria, fungi, viruses and human blood and the sensitivity by using DNA from known number of tachyzoites. The nPCR procedure was done by the standard protocol . Thirty six specimens , consisting of 18 AH and 18 blood samples from 10 clinically suspected toxoplasma chorioretinitis patients and 8 healthy adults who underwent cataract surgery (as controls) were subjected to nPCR. The T gondii specific (IgG and IgM )antibodies were estimated separately by ELISA kit (Biokit, Spain) in all the 36 samples. Results: The nPCR was specific and sensitive to detect one tachyzoite of T.gondii at the end of second round. of nPCR resulting in 96 bp amplified product.. Of the 10 AH from toxoplasma chorioretinitis patients both nPCR and ELISA (only IgG antibodies) were positive in 7, whereas only 2 blood samples were positive by nPCR though ELISA was positive for T. gondii IgG antibodies in 9 of them .Two of the 10 blood samples had inhibitors for nPCR. All the 8AH and 6 blood samples were negative by nPCR and one blood sample was positive by nPCR and another one was positive for IgG antibodies by ELISA. Conclusion: In this study nPCR was found to be a specific and highly sensitive diagnostic tool in AH .specimens of clinically suspected cases of toxoplasma chorioretinitis with an added advantage that collection of it is a simple office procedure. C.R: none
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