Polymerase chain reaction (PCR):
The PCR technique enables the exponential amplification of nucleic acid sequences from any biological samples. In the last few years, the PCR has evolved as an increasingly powerful tool in diagnosis of various pathogens on account of its ability to amplify gene sequences from minute quantities of biological samples. PCR has been successfully used for the diagnosis of many viral, bacterial and parasitic diseases and in understanding the epidemiology of diseases. The versatility of PCR makes it a method of choice not only in medical diagnosis but also in molecular biology research, population genetics and forensic medicine.