Positive Strand RNA Viruses
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37 terms
Terms | Definitions |
|---|---|
 Positive Strand RNA Viruses | these include Picorna-, Calic-, Flavi-, Toga-, and Corona- viridae; replicate in the cytoplasm and have infectious genomic RNA, with viral proteins translated as polyproteins that are post-transationally modified |
| Nonenveloped (+) RNA Viruses | these include Picornaviridae and Caliciviridae; these are all icosahedral |
| Enteroviruses | these cause GI infections, are acid stable, and grow at 37 C; arise from Picornaviridae |
| Rhinoviruses | these cause respiratory infections, are acid labile, and grow at 33 C; arise from Picornaviridae |
| Enveloped (+) RNA Viruses | these include Togaviriae, Flaviviridae, and Coronaviridae |
| IcosahedralViral RNA | this has a polyA sequence at the 3' end but no 5' cap on the RNA; has a virus encoded peptide (VPg) on the end as well as IRES for ribosomes to identify |
| IRES (internal ribosome entry site) | this is the site on the 5' region of icosahedral viral RNA that ribosomes and transcriptional factors identify and attach to in the cytosol |
| VP4 | this poliovirus viral protein is internalized whereas its others are external |
| Polyprotein | this is the state how viral proteins are synthesized; is eventually cleaved by proteases to give rise to structural and nonstructural protein |
| Poliovirus Mode of Action | this virus binds to the 5' cap on the replicative machinery of host cells, cleaving it off and making the host cell replication machinery ineffective while the virus takes over; also turns off host cell apoptosis and other processes through different mechanisms |
| RNA-Dependent RNA Polymerase (RDRP) | this is made when poliovirus begins to replicate; uses the positive strand as a template to make a negative strand which it then uses as a template to make more positive strands to create progeny and proteins at an increased rate |
| Poliovirus | this is an enterovirus that causes infection through the fecal-oral route; mostly restricted to the GI tract with asymptomatic infections BUT can get viremia and it can spread to the CNS, taking up in the motor neurons and causing death by paralysis of respiratory function (RARE) |
| Abortive Poliomyelitis | this is a minor illness that occurs with polio infection which nonspecific symptoms such as headache, sore throat, and nausea |
| Nonparalytic Polymyelitis | this is a rare major illness from polio infection that causes symptoms identical to aseptic meningitis causes by other enteroviruses |
| Paralytic Poliomyelitis | this is a rare major illness from polio infection which causes myalgia and asymmetric muscle weakness followed by muscle paralysis |
| IPV | this was the first vaccine made for polio that was an inactivated form of the virus; did not give great IgA titer |
| OPV | this is the oral live attenuated polio vaccine; gave a greater IgA titer in the GI tract but could recombine with wild polio to cause the disease |
| EIPV | this is the newest polio vaccine that is an enhanced killed vaccine; has IgA titers at moderate levels AND does NOT recombine to cause polio |
| Coxsackievirus | this enterovirus of the Picornaviridae family is a minor childhood disease that causes cold sores |
| Hepatitis E | this Calciviridae causes a virus very similar to hep A that transmits via the fecal-oral route |
| Hepatitis A | this Picornaviridae hepatoviru is caused by the fecal-oral route and gives acute GI distress; self-limiting and usually not chronic |
| Alphaviruses | this Togoaviridaes mostly cause different forms of encephalitis; do NOT spread from person to person; humans are accidentally infected via arthropods |
| Togaviridae | infections with these enveloped viruses come from Alphavirus and Rubivirus; |
| Falviviridae | infections with these enveloped viruses come from Flavivirus and Hepatitis C virus |
| Flaviviridae and Togaviridae | these are non-segmented (+) strand viruses that are enveloped and are mostly arthropod-borne; endocytose into the cell in vesicles |
| Flavivirus | this virus has one open reading fram and only makes one polyprotein; encoded for structural genes at the 5' end; has IRES |
| Togavirus | this virus makes two polyproteins - one that is full sized and makes progeny and one that only makes structural components at the 3' end; NO IRES - capped instead |
| Rubella | this Togavirus is a rubivirus that gives fever, malaise, and maculopapular rash; respiratory transmission; congenital malformations can occur in children whose mothers have this during their first trimester; only has 1 antigenic type so the vaccine is very effective |
| Flaviviruses | these viruses include encephalitius viruses as well as West Nile, Dengue, and Yellow Fever |
| West Nile Virus | this flavivirus has muscle weakness and confusion but can be mostly asymptomatic; humans are a dead end host; know it is around when you see dead birds; similar to Saint Louis Encephalitis Virus |
| Classic Dengue Fever | this flavivirus subtype has fever, rash, severe bone and joint pain with enlarged lymph nodes; self-limiting but persists many months; very little mortality; monkeys to humans via mosquitos |
| Dengue Hemorrhagic Fever and Shock Syndrome | this flavivirus subtype results in shock and hemorrhage after initially appearing with fever, rash, and bone and joint pain; 10% fatal and occurs rarely |
| Ab-Mediated Enhancement | this is thought to be the reason behind Dengue Hemorrhagic Fever and Shock Syndrome; you are infected with it once and make Abs, and then when infected with it again as a different serotype, your premade Abs bind to the virus but do not kill it; allow for rise in immune complexes and infection of macrophages, leading to hemorrhage and shock |
| Yellow Fever | this is transmitted from primates via mosquitos; get jaundice, fever, headache and myalgia which eventually spreads to all organs leading to shock and upper GI bleeds with high mortality; found in the tropics and South America |
| Aedes Mosquitoes | these mosquitoes transmit urban yellow fever from human to human |
| Hepatitis C Virus | this flavivirus is transmitted by contaminated blood with IV drug users, sexual partners, and transplants; get liver damage and possibly liver cancer from overproliferation of the liver trying to repair itself; cases due to transfusion have gone down greatly |
| Coronaviruses | these viruses have glycoprotein spikes and are normally asymptomatic but can cause SARS |
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