The monkeypox virus (MPV, MPXV, or hMPXV), is a species of double-stranded DNA virus that causes mpox disease in humans and other mammals. The monkeypox virus is a zoonotic virus belonging to the orthopoxvirus genus, making it closely related to the variola (VARV), cowpox (CPX), and vaccinia (VACV) viruses. MPV is oval-shaped with a lipoprotein outer membrane. The genome is approximately 190 kb.
The smallpox and monkeypox viruses are both orthopoxviruses, and the smallpox vaccine is effective against mpox if given within 3–5 years before contracting the disease. Symptoms of mpox in humans include a rash that forms blisters and then crusts over, fever, and swollen lymph nodes. The virus is transmissible between animals and humans by direct contact to the lesions or bodily fluids. The virus was given the name monkeypox virus after being isolated from monkeys, but most of the carriers of this virus are small mammals.
The virus is endemic in Central Africa, where infections in humans are relatively frequent. Though there are many natural hosts for the monkeypox virus, the exact reservoirs and how the virus is circulated in nature needs to be studied further.