Viruses Flashcards
Picornaviruses: what are they and what are the 4 common ones?
- naked positive sense RNA viruses that are transmitted fecal-orally (except Rhinovirus, which is transmitted via respiratory droplets
- can be directly translated into DNA material; one long polyprotein that is cleaved into smaller pieces
- includes: Hepatitis A, enteroviruses (polio, coxsackie), and rhinovirus
Poliovirus: what is it and what does it affect, what are 3 clinical manifestations of it, and how does aseptic meningitis present?
- naked acid-stable RNA virus that replicates in Peyers Patches of the gut (lymphoid tissue) and affects motor neurons of the anterior horn of the spinal cord
- causes asymmetric paralysis, respiratory insufficiency, and ASEPTIC MENINGITIS
- aseptic meningitis presents with normal CSF glucose lvls, elevated CSF protein lvls, and most commonly affects children
Coxsackievirus A and B: what are they and how does each virus present clinically? What disease does each virus cause?
- naked positive sense RNA viruses
A: causes “hand, foot, and mouth” disease (red vesicular rash in mouth, palms, and soles), aseptic meningitis; commonly affects young children in the summer
B: causes myopericarditis (dilated cardiomyopathy), “Bornholm” disease or “Devils Grip” (severe unilateral pain in lower chest)
Rhinovirus: what is it and how is it transmitted, what does it bind to in the body, and what is its clinical manifestation?
- naked acid-labile positive sense RNA virus transmitted by respiratory droplets; washing hands reduces infection from foamites (WASH YO FUGGIN HANDS)
- binds ICAM-I of host cells (entry), grows well at 33 C and causes upper respiratory tract infections
- there are over 100 different serotypes, so it is hard to completely treat it
Hepatitis A: what is it and how is it transmitted (2), what are 7 common clinical findings of infection, and what does the virus cause in smokers?
- naked acid-stable positive sense RNA virus usually transmitted by contaminated water (can be boiled, chlorinated, irradiated, etc) in developing countries and contaminated shellfish in developed countries; symptoms typically last for 1 month (no carrier or chronic state)
- causes nausea, vomiting, abdominal pain, jaundice (mainly seen in adults), with smokers who develop it becoming adverse to smoking
- causes hepatitis, gastroenteritis, hepatosplenomegaly
Noravirus/Norwalk Virus: what is it and how is it transmitted, and what is its main clinical presentation?
- naked positive sense RNA virus that is translated into one long polyprotein and cleaved into smaller bits; outbreaks occur frequently in schools and cruises and is associated with consuming contaminated shellfish
- causes explosive watery diarrhea (#1 cause of diarrhea)
Flavivirus: what are they and what are the 4 known viruses of this family?
- enveloped positive sense RNA virus whose genome contains a SINGLE RNA segment
- include Hepatitis C, Dengue Fever, Yellow Fever, and West Nile Virus
Dengue Fever: what is it, how is it transmitted, and what are its two major clinical presentations?
- positive sense RNA virus transmitted by Aedes mosquito
- type 2 fever = “Break Bone Fever”
- classic presentation can progress to dengue hemorrhagic fever (thrombocytopenia/renal failure)
Yellow Fever: what is it, how is it transmitted, and what are 3 clinical findings of infection?
- positive sense RNA virus transmitted by Aedes mosquito
- present with jaundice, severe backache, and is a hemorrhagic fever (bloody stool and vomit)
West Nile Virus: what is it, how is it transmitted, and what are 5 clinical findings of infection?
- positive sense RNA virus transmitted by Culex mosquites from birds
- causes encephalitis, viral meningitis, flaccid paralysis, seizures, and coma
Hepatitis C: what is it and how is it transmitted, what are 3 clinical findings of infection, and what are two molecular findings of infection?
- enveloped (antigenic variation) positive sense RNA virus transmitted via infected blood (needles/blood transfusions) that lacks proofreading exonuclease activity in the 3-5’ direction, making it prone to mutation
- causes hepatitis, jaundice (60-80% develop chronic infection), liver cirrhosis (hepatocellular carcinoma)
- ALT elevated during acute stage (falls after 6 months) and is associated with cryoglobulinemia (IgM precipitate)
Togaviruses (Eastern/Western/Venezuelan/Rubella): what is it and how is it transmitted, what does it typically present with, and how is the adult form different from the congenital form?
- enveloped positive sense RNA virus that are arthropod-borne (arboviruses) commonly transmitted via mosquitoes and cause encephalitis
- rubella is transmitted via respiratory droplets and presents w/tender post auricular/occipital lymphadenopathy, maculopapular rash that spreads from face inferiorly
- TORCH (spread congenitally) causing patent ductus arteriosus, congenital cataracts, sensorineural deafness, and blueberry muffin rash/jaundice
adults rubella infection causes: arthritis of knees/wrists/fingers
one long polyprotein that gets cleaved
Coronavirus: what is it and what are two clinical findings it can cause?
- helical enveloped positive-sense RNA virus
- causes the common cold and upper respiratory tract infections that cause MERS and SARS
Human Immunodeficiency Virus: what is it and what cells does it infect, and what does gag, env, and pol encode for?
- enveloped diploid (two copies) positive sense RNA virus that initially infects macrophages, that allow it to infect CD4+ T helper cells (CCR5 early and CXCR4 late)
gag = p24 protein (conical capsule of RNA strand) env = gp41/120 proteins (transmembrane and surface proteins of the envelope) pol = reverse transcriptase (RNA --> DNA)
Human Immunodeficiency Virus: how does it present accutely, what lvls are patients diagnosed with AIDS, and what are two tests used to diagnose HIV?
acute: flu/mono-like symptoms (cervical lymphadenopathy and pharyngitis), fever
- undergoes a latency period that can last up to 10 years (CD4+ < 200 = diagnoses of AIDS or above 200 in presence of AIDS defining illness)
- pts at risk of Diffuse B Cell Lymphoma
- use ELISA to diagnose (anti-HIV Abs) and Western Blot (detects p24 Ag and confirms HIV)
Influenza Virus (orthomyovirus): what is it and where does it replicate, how is it transmitted, and what two Syndromes can it associated with?
- enveloped negative sense RNA virus that is the only RNA virus that replicates inside the NUCLEUS (all others replicate in CYTOPLASM); genomes composed of 8 segments and exhibits antigenic drift and shift
- transmitted via respiratory droplets and can cause pneumonia (more susceptible to bacterial pneumonia during or after flu)
- no aspirin for kids –> Reyes Syndrome
- encephalopathy, fatty liver, hepatic failure
- Guillain Barre Syndrome –> ascending paralysis
What are Antigenic Drift and Shift? (Flu)
Antigenic Drift (why we need new shots each year)
- point mutations in viral genome
- cause Hemagluttinin and Neuraminidase changes
Antigenic Shift (creates new species: PANDEMICS)
- segments of different virus genomes come together
- forms novel genomes w/virulence factor variation
Influenza Virus: what are the protein Hemagluttin, M2, and Neuraminidase responsible for?
Hemagluttinin (HA) - viral entry into host cells
- binds sialic acid residues
- H1/H2/H3 –> determines cell tropism
M2 protein of Flu A = proper pH for viral encoding
Neuraminidase (NA) - cleaves sialic acid residues
- releases virus from host cells
