An 18 year old college student presents to the student health center complaining of a sore throat and fever. He describes feeling tired for the past few days and repos a loss of appetite. On examination, he has pharyngitis with cervical lymphadenopathy. Blood tests reveal lymphocytosis and the presence of heterophile antibodies. Which of the following best describes the virus responsible for his illness?

In this case, the patient has all the hallmarks of mononucleosis (the heterophil antibodies should have confirmed your suspicion from the history and physical). Mononucleosis is caused by the Epstein-Barr virus, which, in turn, belongs to the herpesvirus family. The herpesviruses are enveloped viruses with double-stranded DNA. Remember that in addition to Epstein-Barr virus, the herpes virus family also includes herpes simplex (1 and 2), varicella-zoster (chickenpox, shingles), and cytomegalovirus (infection in immunocompromised).Cytomegalovirus also causes infectious mononucleosis, but in these patients the heterophil test is negative. There are two families of viruses that are non enveloped with double-stranded DNA: papova viruses and adenoviruses. There are many families of viruses that are enveloped with single-stranded RNA: arenaviruses, bunyaviruses, coronaviruses, filoviruses, flaviviruses, paramyxoviruses, ohomyxoviruses, retroviruses, rhabdoviruses, and togaviruses. Parvoviruses are the only family of DNA virus with single-stranded DNA. They do not have an envelope. Ref: Levinson W. (2012). Pa IX. Brief Summaries of Medically Impoant Organisms. In W. Levinson (Ed), Review of Medical Microbiology & Immunology, 12e.