Morphology + Biology of Viruses Flashcards
How can we classify viruses? (13)
Type + organisation of genome DNA/RNA ss/ds Genome relatedness Viral replication strategy Structure + size Envelope? Host range Tissue tropism Pathogenicity Mode of transmission Physiochemical properties Antigenic properties
What is most common viral structure? (1)
Isohedral
Which viruses are in the Herpesviridae family? (4)
HSV 1
HSV 2
Epstein Barr virus
Varicella Zoster
What are characteristics of Herpesviridae viruses? (4)
Isohedral nucleocaspid
Linear dsDNA
Enveloped
Periods of latency + reactivity
What are characteristics of HIV? (4)
Envelope
Viral gp120 + gp141
2 copies of RNA
Reverse transcriptase, integrase + protease
What are the 5 human hepatitis viruses? (5)
A = enteric trans B = non-enteric, persistant C = non-enteric, persistant D = non-enteric, persistant E = non-enteric
What do we treat Hep A-C with? (3)
A = vaccine B = vaccine C = interferon therapy, 50% effective
What are characteristics of HepA virus? (4)
Most common viral hepatitis No envelope (naked) Isohedral ssRNA \+ve sense = viral RNA can act directly as mRNA
What are clinical features of HepA? (6)
Incubation = 15-45 days Acute onset Children + young adults Foecal-oral transmission most common Percutaenous transmission unusual Sexual transmission unlikely
What are characteristics of HepB virus? (4)
Enveloped 42nm Isohedral Circular DNA, partially double stranded Complete virus + incomplete particles
What are clinical features of HepB virus? (5)
Incubation = 30-150days Insidious or acute onset YAs, babies, todlers Percutaneous, perinatal or sexual transmission (sharing needles, unprotected sex) Risk of cancer
Where is HepB found? (3)
In body fluids e.g. semen, saliva, blood
What are characteristics of HepC virus? (4)
Enveloped Isohedral ssRNA NS1 (non-structural protein 1) E proteins = major envelope proteins
What are risk factors for HepC? (8)
Pre-1992 blood transfusion Body piercing/tattoo Haemophilia IV drug use Needle stick injury Non-sterilised injections Vertical transmission Sexual transmission
What are clinical features of HepC virus? (7)
Incubation = 15-120days Insidious onset Any age, more common in adults Pericutanous transmission iscommon Perinatal/sexual less so Cancer risk Can cause hepatocellular carcinoma + liver cirrhosis
What are characteristics of norovirus? (5)
Diarrhoea Common cause of infectious gastroenteritis Icosahedral Non-enveloped Single-stranded RNA
What are characteristics of rotavirus? (4)
Most common in infants + young kids (but adults + older kids can also become infected) dsRNA (segmented into 11 segments) Non-enveloped Triple layer caspid Isocahedral structure
Symptoms of rotavirus? (2)
~2days after exposure for symptoms to appear
Fever, diarrhoea, vomiting, ab pain
How do we treat rotavirus? (2)
No antivirals
Live oral vaccine available
What are the viral proteins of rotavirus? (3)
Structural = VP1-VP7
VP7 + VP4 are important in virus attachment + entry
Non-structural = NSP1-NSP6
How does rotavirus replicate? (10)
Infects cells of intestinal epithelium
Virus binds to receptors + enters cells by endocytosis
Loses outer layer
Within virus structure dsRNA can replicate as VP6 act as channel + allows movement of RNA
VP1-3 inside virus core are involved in transcription
Viral proteins are made in infected cell cytoplasm
Core assembly of single + double shelled particles in cytoplasm
Entry of double layered particle into ER
Acquires outer shell
Released from cell
What are the symptoms of measles? (5)
Fever, runny nose, red eyes sore throat
Koplik’s spots (small, white) may appear inside mouth (day 2/3)
Rash appears on face + spreads downwards (day 3-5)
Fever may spike when rash appears
After few days, fever subsides + rash fades
