Tuesday, January 17, 2012

Biosensor Technology for Snake Venom

The following story by T. Nandakumar is from The Hindu, originally published in November 1, 2011 and was sent by Dr. A. Buji Kumar.
Naja naja, JCM
A team of researchers at the State Inter-University Centre for Excellence in Bioinformatics (SIUCEB) under the University of Kerala is working on the development of a biosensor for identification of snake venom that could help bring down the mortality rate of snake bite victims in the country significantly.

The State-funded project, essentially an amalgamation of biology and electronics, will enable targeted treatment of snake bite victims by precise detection of the type of snake. The sensor under development is a gadget like a glucometer that can read a strip laced with the body fluid of a snake bite victim and provide a read out on a screen. The blood, urine or fluid from the bite site can be used to analyse the specific type of venom. The prototype of the biosensor is expected to be ready in eight months.

According to WHO estimates, India has the highest number of deaths (35,000 to 50,000 a year) due to snake bites. The States with the largest number of snake bite cases include Kerala, Maharashtra, West Bengal, Uttar Pradesh, and Tamil Nadu.

In India, the conventional clinical practice is to administer polyvalent anti-snake venom (ASV) which comprises antibodies of four different species (Big Four), namely the Spectacled (Indian) cobra, the Common krait, Saw-scaled viper and Russell's viper, that account for most of the bite cases.
The polyvalent method accounts for the high incidence of snake bite deaths in India. It often causes severe allergic reaction in the victim, (seen in up to 30 per cent of the recipients worldwide) demanding secondary treatment.

Australia has the highest number of venomous snakes, yet the number of death cases is less because the country follows the targeted monovalent technique based on identification of species using a snake venom detection kit.

“The polyvalent treatment method results in collateral damage, affecting internal organs. To confirm a snake bite, doctors often wait for symptoms like dizziness, nausea or imbalance, typical of neurotoxins, or anti-coagulation of blood that is characteristic of haemotoxins. The delay can lead to complications or death,” says R. Dileepkumar, Post Doctoral Fellow at SIUCEB and principal investigator of the project.

The biosensor, based on ELISA (Enzyme Linked Immuno Sorbent Assay) technology, will obviate the need to wait for symptoms and avoid the complications inherent in administering polyvalent antivenom.

The project team at SIUCEB is currently raising antibodies in mammalian models against the Big Four species that account for the maximum number of snake bites in India.

The sensor is expected to overcome many limitations in the conventional approach like cross reactivity and sensitivity, says Mr. Dileepkumar. “It can also be used to quantify the extent of envenomation (to determine the dose of monovalent ASV required) and to monitor the venom clearance from the body,”

When a snake bite victim is brought to the hospital, the doctor or technician collects body fluids from the person and applies them to the strips coated with species-specific antibodies. The unreacted materials in the fluid are washed off and the strips are administered with enzyme-labelled secondary antibody that can generate electrons measurable as electric current for a reaction. The strips are then inserted into the biosensor to give a reading that can be classified as one of the Big Four venoms.

While the technical design of the biosensor is complete, the biological study is on. Mr. Dileepkumar says efforts are on to tie up with research institutions in the Middle East for sourcing more stable antibodies raised from the camel. This, he says, would avoid the need to store the strips at low temperature.

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