RNA viruses Flashcards
What are the 3 types of Paramyxoviruses?
1-Rubeola virus
2-Parainfluenza
3-Mumps
What are the 2 categories of RNA viruses?
Paramyxoviruses and Togaviridae
What is the basic description of paramyxoviruses?
Enveloped, negative strand RNA viruses, Helical symmetry
Measles is known as what?
Rubeola virus
Rubeola virus has what? but also lacks?
Rubeola Has- hemagglutin(surface glycoprotein) for attachment to host cell, Lacks- neuraminidase (aids in the efficiency of virus release from cells)
What is the main route of infection for Rubeola?
inhalation of respiratory secretions
Does Rubeola show outward symptoms?
Yes, almost all infected individuals show signs of disease
Rubeola virus is broken down into 2 forms(measles)
Measles uncomplicated and measles complications
What is the pathogenesis of measles uncomplicated?
Fever, running nose, caugh, conjunctivitis, Koplick’s spot on mucosal membranes (small, irregular, white spots, with bluish halo), Maculopapular rash which extends from the face to the extremities
What are the possible measles complications?
- impaired cell mediated immune response(continued growth of the virus in the lungs-can be fatal) rare
- Otitis media and bacterial pneumonia are quite common
- 1in 1000 cases get encephalitis
- Sub-acute sclerosing pan encephalitis-progressive neurological disorder characterized by inflammation of the brain
What are the ways measles is controlled?
Rubeola virus has only one serotype(antigenic type)
Provides life long immunity
Attenuated live vaccine -MMR
What is the second type of paramyxoviruses?
Parainfluenza
How many types of parainfluenza are there and what do they all do?
4 types, all of which can cause upper respiratory infections or lower respiratory infections especially important in children because it is responsible for approximately 40-50% of croup cases
What is the 3rd type of Paramyxovirus?
Mumps
What does mumps cause and what does it infect?
Causes swelling of salivary glands (parotid glands), virus infects upper/lower respiratory tract leading to local replication. The virus spreads to lymphoid tissue which leads to viremia(when a virus enters the blood stream and has access to the rest of the body)
What are two possible complications with mumps?
Orchitis(testicular inflammation) and aseptic meningitis
What is used to control mumps?
MMR-vaccine (single serotype of mumps, life long immunity)
2nd of the two groups of RNA viruses is?
Togaviridae
Togaviridae is known as?
Rubella(german measles)
Basic description of German measles?
Positive strand RNA virus
Enveloped
Icosahedral symmetry
only member of the rubrivirus genus of the Togavirus family
What is the transmission and infection of german measles?
- Transmitted by respiratory secretions
- Initial site of infection is the upper respiratory tract. The virus replicates locally in the lymph nodes leading to viremia and spread to other tissues
- Rash (if it occurs) starts after an incubation period of approximately 2 weeks
Togaviridae congenital infection has the highest risk to the fetus when?
In the first few weeks of pregnancy and then declines in terms of both frequency and severity but continues on into the second trimester
Togaviridae congenital infection infects the fetus how?
through infection of the placenta
Togaviridae congenital infection in non-immune mothers can lead to what in 80% of neonates?
- Hearing loss
- Mental retardation
- Congenital heart problems
- Neurologic problems
- Ophthalmic problems
- Congenital infections can infect others after birth for a year
