Lecture 6 - Pos Strand RNA Viruses Flashcards
Positive Strand RNA Viruses
______ are small (as the name suggests) RNA viruses that don’t have an ______ and are _____-stranded ____sense RNA.
Picornaviridae
Envelope
Single-stranded
Positive sense
Rhinoviruses and Enteroviruses are both of the _______ family. They are both icosahedral, but ______ are labile at low pH and high temp (replicating in respiratory tract), while _______ are resistant to low pH and high temp (passing through stomach to replicate in intestine.)
Picornaviridae
Rhinoviruses
Enteroviruses
The VP1 protein of Picornaviruses interacts with cellular ______-1, facilitating adhesion.
ICAM-1
Picornaviruses have a positive sense RNA genome that has a ____ protein at its 5’ end instead of a Cap, and the genome is translated into a _______ that is cleaved by two viral proteases: ____ and ____. Because positive sense ssRNA viral genomes can be immediately transcribed by the host cell, they don’t need to bring with them a viral RNA-______ for transcription.
VPg
Polyprotein
2A and 3C
RNA-Polymerase
In order for + sense ssRNA viral genomes to be replicated, the viral RNA-pol creates a ____sense genome as a template.
Negative sense
Enteroviruses are typically passed via ____/____ route (should make sense given they infect the intestines.) They can spread to other tissues, including the ______, and are shed in _____.
Fecal/Oral
CNS
Feces
The most important Enterovirus is _____. There are ____ serotypes, and only humans (mostly _____) are infected. The virus attacks motor _____ cells leading to _____ wasting and paralysis.
Poliovirus
3 serotypes
Children
Nerve cells
Muscle wasting
About 95% of Polio infections are subclinical, 4% of the time ____-like symptoms can be observed, and about 1% of the time it can cause _____.
Flu-like symptoms
Paralysis
Jonas Salk used _____ to “kill” the Polio virus in order to use cultures for vaccines.
Formalin
Sabin created an oral polio vaccine by isolating forms of live attenuated virus that would replicate in the _____ rather than in the CNS.
Intestines
One of the issues with using the live attenuated polio vaccine is that it can _____ in vivo, reverting 11 base difference in the _____ region of the vaccine virus back to the wild type, allowing it to infect neurons.
Mutate
5’ UTR
Coxsackieviruses are another type of Enteroviruses. They have a typical incubation period of ___-___ days. Most often, Coxsackie infection causes ___-like symptoms and “____, ____, and ____” disease. Serotype EV71 in China and _____ in the U.S. were cause for creation of vaccines.
2-10 days
Flu-like symptoms
Hand, Foot, and Mouth disease (characterized by blisters.)
EV D68 in the U.S.
______ are the most common viral infectious agents in humans and cause about 50% of all ____ ____ cases. Keep in mind they differ from enteroviruses in two key ways: they are sensitive to _____ and ______. They can be spread via _____ or direct contact, causing upper resp infections. Primary infection results in _____ production in nasal secretions and _____ production in the bloodstream, leading to an immune response and resolution of the disease. There is NO VACCINE because there are more than 110 serotypes.
Rhinoviruses
Common Cold
Low pH and High Temp
Aerosols
IgA in nasal secretions
IgG in bloodstream
Caliciviridae is another family of ___-sense __RNA viruses that lack an ______ (like Picornaviridae.) There are two important types: ____ (NLV) and ____ (SLV.) ____ is the major cause of non-bacterial gastroenteritis leading to diarrhea. Both NLV and SLV are transmitted via ___/___ and there is no vaccine or specific treatment available.
Positive-sense
ssRNA
Envelope
Norovirus
Sapovirus
NLV
Fecal/Oral
Astroviridae (star-like structure under EM) is another family of viruses with the same genomic and virion structure as Picornaviridae and Caliciviridae. It is a leading cause of gastroenteritis in _____ and _____ _____.
Infants and Young Children
