The scientists at the Hyderabad-based Centre for Cellular and Molecular Biology (CCMB) have developed a DNA based diagnostic chip for identifying more of the 15 pathogens that cause eye disease.

A paper published by the CCMB scientists headed by Dr Ch Mohan Rao and comprised of Dr K Sridhara Rao and Dr P V Ramchander, said " A unique set of DNA sequences are identified and primers designed to meet critical parameters of large multiplexing in a single reaction." The identification of the pathogen was based on the hybridization of PCR (polymerase chain reaction) amplified DNA sequences with specific target sequences immobilised on a membrane. The hybridization would be visualised by colour development, the paper said.

The DNA chip, Dr Rao said, "Is a very sensitive and requires a small sample volume (only a few micro litres)". The complete test can be done with minimum facilities at district level hospitals, too, without the need for trained personnel. After the successful demonstration of the efficacy and diagnostic potential of the chip at the laboratory level at the CCMB, the technology was transferred to the Bangalore-based Xcyton Diagnostics for product development.

Though the present product was for diagnosing ophthalmic infections, the same pathogens can be detected in other infections, too, with different samples, such as blood, cerebrospinal fluid, etc. The same principles and technology can be extended to identification of infecting organisms in other diseases as well, the scientist said.

The clinicians at the L V Prasad Eye Institute in Hyderabad, Sankar Nethralaya in Chennai and RP Centre in New Delhi, helped in the development of the DNA chip.