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Is Possible to Use Long Time Formalin-Fixed Cryptosporidium Oocysts for Polymerase Chain Reaction?

Inventing PCR technique made a great progress in the field of medical diagnostic, legal affairs, archeology and so on. Early detection of some infections like toxoplasmosis, rubella and etc are important in view of preventing undesired outcomes. Formalin-fixed archival samples are one of the popular source of diagnostic materials but, however are known to be poor materials for molecular biology applications. These are the easiest to store and transport. They are often used as the source of nucleic acids for retrospective molecular analyses based on DNA amplification by polymerase chain reaction. We conducted a series of experiments to understand possibility of doing polymerase chain reactions on materials fixed for a long time. Two human stool samples and two cattle samples contained Cryptosporidium oocysts, that had been stored for a long time, used for experiment. DNA extraction were done by serial freeze and thaw and phenol chloroform method. Some modifications were done in usual PCR technique, for example altering the time of anealing step, to repeat this step and other modifications. Employing some modifications in the anealing step, and repeat of this step one or two times, showed that it can be possible doing PCR with long time formalin-fixed materials. Extraction of DNA by such method was not impossible but difficult. Also our results showed that two isolates of Cryptosporidium from human and cattle genetically were the same. Formalin-fixed clinical materials can use for diagnostic purposes.