In a development that may have widespread ramifications on the national immunisation policy, researchers at the Armed Forces Medical College (AFMC) have identified a wild type of virus that causes chicken pox in the country. This is entirely different from the vaccine strain of the virus and hence, explains why the disease still occurs despite vaccination. Col K K Lahiri, Professor, Department of Microbiology, who embarked on the project a year ago, studied 111 cases where armed services personnel had caught the infection in transit. “These cases represent the entire country,” says Dr K Kaushik, who had taken up the research as part of her thesis on ‘Molecular Characterisation of Wild Indian Strains of Varicella Zoster and Differentiation from the Vaccine Oka Strain’. The paper and its findings were adjudged as the best at the national conference of the Indian Association of Medical Microbiologists held in Nagpur recently. In fact, the research clearly highlights that the current vaccine for chicken pox—which is being imported—is not very effective in India, as it has been developed using a Japanese strain of chicken pox. At least 50 gene sequences of the strain have been submitted to GenBank—the US’ National Centre for Biotechnology Information Database—Col Lahiri said. There are around 4 million cases of chicken pox every year in India and the disease causes as many as 10,000 deaths. What was alarming was that at least 20 per cent of the people who had contracted the infection at an early stage of their life have had a relapse. “It was an intriguing dilemma. So, we took the vesical fluid, sequenced the virus using Polymerase Chain Reaction (PCR) technology, amplified the DNA and then identified how different the Indian circulating wild type of virus was from the present vaccine strain,” Col Lahiri said. In medical terms, the research team profiled the VZV genes 38 and 54 by PCR and then genotyping within the circulating Indian strains and that of the oka vaccine strains. This study has pinpointed the exact version of chicken pox in the country. “What is required now is to modify these strains to develop an India-specific vaccine against chicken pox,” Col Lahiri added.
