Hello Snehal!

For becoming a Virologist, it is essential to have Biology/Biotechnology at your (10+2) level. Given that you've passed your 12th with Biology or Biotechnology as one of your core subjects securing 60% and above in aggregate, the next step is completion of a bachelor's degree in Life Sciences or BVSc (Bachelor of Veterinary Science) or BSc Medical Laboratory Technology or MBBS or BSc Biotechnology or BSc Microbiology/ Biochemistry/Zoology or any other related subject with over 50% aggregate marks or 6.5 CGPA from a recognized institute.
Then, you will be eligible to pursue the 2 years duration course of M.Sc. in Virology, followed by a Ph.D. programme of 3-5 years.

Some good colleges in India offering M.Sc. in Virology are :

1.Savitribhai Phule Pune University, Maharashtra
2.Amity Institute of Virology and Immunology, Noida
3.Sri Venkateswara University, Tirupati
4.Manipal University, Karnataka

Criteria for admission in each step may vary from one institute to another.

After completing your Ph.D. , you can join any research centre or lab as a Virologist.

Please feel free to ask if you have any more queries.
I hope this answer will help you.