What virus is recognized as the causative agent of infectious mononucleosis?

Infectious mononucleosis is primarily associated with the Epstein-Barr virus (EBV), a member of the herpesvirus family. EBV is particularly known for its role in causing infectious mononucleosis, which is characterized by symptoms such as fatigue, fever, sore throat, and swollen lymph nodes. The virus is commonly spread through saliva, which is why it is sometimes referred to as the "kissing disease."

EBV infects B cells, leading to their proliferation, which contributes to the atypical lymphocytes observed in the laboratory findings of affected individuals. Along with clinical symptoms, serological tests often reveal positive heterophile antibodies, which are indicative of an EBV infection. This relationship between EBV and infectious mononucleosis is well-established in medical literature, making this choice the most accurate one.

In contrast, other viruses listed—such as cytomegalovirus (CMV), herpes simplex virus (HSV), and varicella-zoster virus (VZV)—can cause different infections, but they are not primarily responsible for infectious mononucleosis. CMV can cause a mononucleosis-like syndrome, but it is EBV that is classically linked to the condition. Understanding the specific roles of