Pune: The National Institute of Virology (NIV) has found the presence of Clade 9 variant of chickenpox-causing varicella-zoster virus (VZV) for the first time in the country in its latest study, laying renewed emphasis on genome surveillance.
Varicella zoster virus is one of nine known herpes viruses infecting humans. It causes chickenpox, primarily in children and adolescents, and shingles in adults. A clade is a subtype, genotype or group arising from a common ancestor.
Of the 331 suspected cases of VZV assessed in the study, 28 with vesicular rashes were found positive for VZV. Their analyses confirmed the circulation of Clade 1, 5 and 9 in the country. While Clade 1 and 5 were earlier detected in the country, it is for the first time that Clase 9 has been detected in India, the study showed.
NIV scientist Dr Pragya Yadav, who is also one of the authors of the study, said, “The Clade 9 is the most common VZV strain in circulation in countries like Germany, UK and US. However, this is the first study reporting the circulation of VZV Clade 9 in India.”
She said, “Despite the detection of VZV Clade 9 variant in India, there were no significant indications of heightened disease severity in the patients. Owing to the increased surveillance during the COVID-19 pandemic, we were able to detect the new clade.” The study was published in ‘Annals of Medicine’ on September 6. “There was need for more studies on the difference in the intensity, symptoms and rate of transmission of Clade 1, 5 and 9,” Dr Yadav said.