``We are looking for collaborators to initiate trials in monkeys,'' Dr Sita Naik from SGPGI's Department of Immunology, told PTI.

Deoxyribonucleic acid or DNA vaccines, in which the DNA microrganism is introduced directly to generate antibodies and an immune response, have stirred interest among immunologists the world over.

The currently available protein-based vaccines only generate antibodies but do not activate cells of the immune system.

Scientists describe DNA vaccines as signalling a possible revolution in vaccinology, due to its ease of production and stability.

SGPGI researchers prepared the vaccine by first cloning a specific `S' gene of hepatitis B virus and later introducing this gene into a`plasmid' (genetic material found outside chromosomes, inside bacteria).

On injecting the plasmid containing the hepatitis B gene into mice, they found that it generated antibodies in high levels and also activated cells of the immune system, Dr Naik said.

The findings were reported by Naik's colleague Sunita Dwivedi at the ongoing International Congress on Immunology here.

India initiated research in this frontier area of science about a couple of years ago, and work on DNA vaccines against Kala Azar, Japanese encephalitis, malaria and hepatitis-B are under study.

Laboratories engaged in this research include the Indian Institute of Science in Bangalore and National Institute of Immunology (NII) here.

An NII team is working on a DNA vaccine against Japanese encephalitis virus, a mosquito-borne virus responsible for acute encephalitis in humans with high fatality rates.

The NII scientists have produced plasmid vectors that carry genes for two crucial proteins responsible for generatingantibodies.

Mice immunised with these plasmid vectors generated sufficient antibodies, a report presented by NII researchers Sudanshu Vrati and colleagues at the Congress said.

Several groups abroad have already obtained exciting leads in DNA vaccine research. Scientists from the University of Pennsylvania and University of Florida in Tampa are jointly studying a DNA vaccine against the AIDS-causing Human Immunodeficiency Virus (HIV-1) strain, based on multiple gene sequences.

Scientists have achieved protective immunity in animals with DNA vaccines against pneumonia, diarrhoea, tuberculosis and malaria, H L Robertson, from Yerkes Regional Primate Research Centre of Emory University in Atlanta, reported at the Congress.

Work on birth control vaccine on: Developer

NEW DELHI: Work on the controversial birth control vaccine has not stopped and criticism against it ``is not based on facts'', its developer G P Talwar told the ongoing Global Conference of Immunologists here today.

He was reactingto statements from Judith Richter, a scientist-turned-activist from Germany and representative of the `Global Network for Women's Rights', who was trying to interrupt a session where Talwar was speaking on a different topic.

Talwar, who is now with the International Centre for Genetic Engineering and Biotechnology, denied India had stopped work on the vaccine.

``The chapter is not closed,'' he said. ``Work is continuing to improve it so that it works in all women.'' In its present form it works in only 80 out of 100 women who must take it two or three times a year.

He said contrary to propaganda by women activists, the World Health Organisation too had not abandoned work on its own anti-fertility vaccine.

Pointing out that the contraceptive vaccine ``widens the option'', he appealed to women activists to base their criticism, ``on facts, not fallacies'.

Indian research on the birth control vaccine, however, found support from several participants at the conference.