viruses Flashcards
what is the difference between positive stranded RNA viruses and negative stranded RNA viruses?
Positive stranded RNA - RNA can be used directly as mRNA and immediately translated into proteins
Negative stranded RNA - mRNA must be transcribed via a virus RNA dependent RNA polymerase first, before it can be used for translation
what is the only family of double stranded RNA viruses?
reoviridae
helical capsids are associated with what type of viruses?
RNA viruses
What are the DNA viruses and what are their general characteristics?
HHAPPPPy viruses - herpes, hepadna, adeno, papilloma, parvo, pox, polyoma. Most DNA viruses are double stranded, icosahedral capsids and replicate in the nucleus
which two DNA viruses break the rules?
parvoviridae has a single strand genome. Poxviridae does not have icosahedral capsid and replicates in the cytoplasm
enveloped DNA viruses
Herpes, hepadna, pox
naked (nonenveloped) DNA viruses
papilloma, adeno, parvo, polyoma
what are the general characteristics of RNA viruses?
single stranded, enveloped, helical capsid, replicate in the cytoplasm
which RNA viruses are naked (non enveloped)?
picorna, calici, reoviridae
which RNA viruses have icosahedral symmetry?
picorna, calici, reo, toga and flavi
which RNA viruses replicate in the nucleus?
retro and orthomyxo
What are the positive stranded RNA viruses?
The Calcified old emperor Pico is wearing his crown and toga while eating flavorful grapes from a retro bowl - calici, pico, corona, toga, flavi and retroviridae
what are the negative stranded RNA viruses
Old Pete’s Rabid dog Filo fights Paul Bunyon in the arena - orthomyxo, paramyxo, rhabdo, filo, bunya, arenaviridae
Which two viruses cause the common cold?
Coronaviridae and rhinovirus
What virus causes SARS? What are the clinical manifestations of SARS?
A coronavirus. Fever, chills, myalgias, dry cough, pleurisy, dyspnea but no rhinorrhea or sore throat. Can progress to ARDS
Which four viruses cause diarrhea?
Caliciviruses (Norwalk and noroviruses), rotavirus, adenovirus, astrovirus
what are the five viruses in the paramyxoviridae family?
parainfluenza, metapneumovirus, respiratory syncytial virus, measles (rubeola), mumps
what are the clinical manifestations of mumps virus?
URIs, parotitis, orchitis (swelling of the testicles), meningitis and encephalitis
what are the clinical manifestations of the measles virus?
prodrome (high fever, conjunctivitis, photophobia, hacking cough, rhinitis and malaise), Koplick’s spots, maculopapular rash that spreads from the head downwards
what is the clinical manifestation of respiratory syncytial virus?
pneumonia. Most common cause of pneumonia in young kids.
what is the most common viral cause of croup?
parainfluenza virus
what are the clinical characteristics of croup?
stridor, barking cough, hoarseness
what are the six most common viral causes of respiratory illnesses in children?
parainfluenza, respiratory syncytial virus, metapneumovirus, rhinovirus, coronavirus and adenovirus
what two types of illnesses can adenovirus cause
respiratory infections and diarrheal illnesses
what are the characteristics of the paramyxoviridae family?
negative sense, single stranded RNA viruses. Helical symmetry. Replicates in cytoplasm. Unsegmented genome. HA and NA activity. Fusion protein.
what are the characteristics of the orthomyxoviridae family?
negative sense, single stranded RNA virus. Helical symmetry. Replicates in the nucleus. Segmented genome. HA and NA activity
what are the common viral causes of aseptic meningitis?
enteroviruses (coxsackieviruses, echovirus, numbered enteroviruses), mumps, herpesvirus, tick-born and West Nile viruse
what are the four families of viruses that cause diarrhea?
calciviruses (Norwalk virus, norovirus), rotavirus, adenovirus, astrovirus
what are the TORCHES organisms and what do they do?
These organisms can cross the blood-placenta barrier and cause disease in the fetus. TO = toxoplasmosis, R = rubella, C = CMV, HE = herpes and HIV, S = syphilis
what is the most common cause of viral meningitis in the US?
enteroviruses
what cell type does Epstein-Barr virus infect? What disease does it cause? what will blood work up show?
EBV infects B cells and causes EBV-mononucleosis. Blood smear shows an atypical lymphocytosis. The mono spot test tests for heterophile antibodies
which one of the hepatitis viruses is a DNA virus? What are the characteristics of its DNA? what family does it belong to?
hepatitis B virus (hepadnaviridae). It has circular double stranded DNA. It can insert into the host hepatocyte genome and turn on oncogenes, increasing an infected patients risk of hepatocellular carcinoma
what is the treatment for hepB infection?
interferon-alpha, reverse transcriptase inhibitors, prevention: vaccine with HBsAg
What do HBeAg and anti-HBeAg indicate about a patient’s infection?
HBeAg indicates high infectivity and active disease
Anti-HBeAg indicates low infectivity and non-active disease
what antigens and antibodies would you see in an acute hepB infection?
positive: HBeAg, IgM-HBcAg, HBsAg
negative: anti-HBeAg, IgG-HBcAg, anti-HBsAg
what antigens and antibodies would you see in a chronic hepB infection?
positive: HBsAg, IgG-HBcAg
negative: anti-HBsAg, IgM-HBcAg
+/- HBeAg
what antigens and antibodies would you see in a person immunized to hepB?
positive: anti-HBsAg
negative: everything else
To what family does the hepatitis A virus belong? What are the characteristics of that family?
picornaviridae -> hepatovirus. positive sense, single stranded RNA, icosahedral capsid, non-enveloped
what are the clinical manifestations of hepatitis A virus?
acute hepatitis that never becomes chronic
To what family does hepatitis C virus belong? What are its morphologic characteristics?
flavivirus. Positive sense, single stranded RNA virus, enveloped, icosahedral capsid
what is the treatment for hepC infection?
all HCV - pegylated IFN-alpha + ribavirin
HCV1 - pegylated IFN-alpha + ribavirin + NS3/4A protease inhibitor (simeprevir, telaprevir, boceprivir)
which virus needs coinfection with hepB to be infectious?
hepatitis D virus
what population does Norovirus most commonly infect?
older children and adults, cruise ships, high schools, ect
To what family does rotavirus belong? What are the characteristics of that family?
Reoviridae. Double stranded RNA virus, non-eveloped.
What population does Rotavirus most commonly infect?
young children and infants (almost everyone is infected by age 5)
which virus has an enterotoxin? What does it do?
Rotavirus has an enterotoxin, NSP4, that stimulates enterocytes to pump more ions into the intestinal lumen (secretory diarrhea)
What vaccines are available to prevent rotavirus?
RotaTeq - mostly an animal strain, but with a few human RNA segments substituted in
RotaRix - an attenuated version of the most common human strain
What is Reye’s syndrome?
potentially fatal damage to many organs associated with aspirin consumption in children with viral illnesses.
What are the three arbovirus families? What disease do they cause?
Flaviviridae, togaviridae, bunyaviridae
Flavivirus - dengue fever, yellow fever, West Nile virus, St. Louis encephalitis,
alphavirus (togaviridae) - eastern equine encephalitis, western equine encephalitis
bunyaviridae - hantavirus, La Crosse encephalitis
What are the killed/subunit vaccines?
Hip, Hip, Hooray! Polio Is Removed (from the face of the earth)
Hep A
Hep B
HPV
Polio (Salk)
Influenza (2 strain of influenza A, 1 strain of influenza B)
Rabies (given as post-exposure prophylaxis)
What are the live attenuated vaccines?
MR Sabin Sells Rotten Yellow Chickens MMR Polio (Sabin) Shingles Rotavirus (rotarix, rotateq) Yellow fever Chickenpox
