Researchers tracked the recovery of 68 patients in Mumbai, India, to study the gender disparity of the virus, which has taken a worse toll on men, according to a preliminary report posted on MedRxix, which hosts unpublished medical research papers that have not been peer reviewed.

Dr. Aditi Shastri, an oncologist at Montefiore Medical Center in the Bronx, and her mother, Dr. Jayanthi Shastri — a microbiologist at the Kasturba Hospital for Infectious Diseases in Mumbai — said the virus attaches itself to a protein that occurs in high levels in the testicles.

This protein, known as angiotensin converting enzyme 2, or ACE2, is present in the lungs, the gastrointestinal tract and the heart in addition to large quantities in the testicles.