Poxvirus Flashcards
What are the general properties of Poxviruses?
Poxviruses are large enough to be seen as featureless particles by light microscopy. By electron microscopy, they appear to be brick-shaped particles measuring about (300–400) × 230 nm. Their structure is complex and conforms to neither icosahedral nor helical symmetry. The external surface of particles contains ridges. Poxviruses have double-stranded DNA. Unlike all other DNA viruses, Poxviruses replicate in the cytoplasm.
Which genera of Poxviruses can cause disease in humans?
Most of the poxviruses that can cause disease in humans are contained in the genera: Orthopoxvirus, Parapoxvirus, Molluscipoxvirus, and Yatapoxvirus.
What are some examples of Orthopoxviruses?
The Orthopoxviruses include: variola, vaccinia, monkeypox, cowpox, mousepox, and camelpox viruses. The first four are infectious for humans.
What is smallpox and how was it eradicated?
Smallpox is an acute contagious disease caused by the variola virus. It was one of the most devastating diseases known to humanity and caused millions of deaths before it was eradicated.
What is monkeypox and how is it transmitted?
Monkeypox is a viral infectious disease caused by the monkeypox virus. It can cause a painful rash, enlarged lymph nodes, fever, headache, muscle aches, and back pain. Monkeypox is mostly transmitted to people from animals, with limited secondary spread through human-to-human transmission. It can spread between humans through close contact of any kind, including through kissing, touching, oral and penetrative vaginal or anal sex with someone infectious.
What are the characteristics of Parapoxviruses?
Parapoxviruses are morphologically distinctive compared with the Orthopoxviruses. They are slightly smaller particles (260 × 160 nm), and their surfaces exhibit a crisscross pattern. The Parapoxviruses have a narrow host range. They include: Orf, Pseudocowpox, and Bovine papular stomatitis viruses.
What is Molluscum contagiosum and how is it transmitted?
Molluscum contagiosum causes benign skin nodules in humans. It occurs only in humans. The lesions of this disease are small, pink, wart-like tumors on the face, arms, back, and buttocks. Molluscum can be spread by touching an infected person. It can also be spread when touching items that contain the virus such as towels, clothing, toys, or pool equipment used by a person with the virus.
What are Yatapoxviruses and what do they cause?
The Yatapoxviruses have a narrow host range (infect monkeys). They include: Tanapox and Yabapox viruses. These viruses cause localized lesions in humans (rare). Tanapox and Yaba monkey tumor viruses are serologically related but distinct from all other poxviruses. They are morphologically similar to Orthopoxviruses.
What is cowpox and how does it affect humans?
Cowpox is a mild disease of cows caused by cowpox virus. It is extremely rare but occurs sporadically in enzootic areas. Infection of humans occurs by direct contact during milking, and the lesion in milkers is usually confined to the hands. The disease is more severe in unvaccinated persons than in those vaccinated with the smallpox vaccine.
