CSB351Y1 Lecture Notes - Lecture 20: Coxsackievirus, Picornavirus, Enterovirus
26 May 2018
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Lecture 22: Hepatitis virus A, Coxsackievirus
Hepatoviruses
• Hepatitis A (HAV) originally thought to be enterovirus but now known as unique genus of picornaviridae
- Attracted to liver, absent VP4 protein, high thermostability
• Icosahedral but only VP1,2,3 (VP4 uncertain, ORF encoding it identified)
• Highly resistant to thermal denaturation and acidic conditions, detergent inactivation
• VPg linked to 5’ end, 3’ polyadenylated, contains IRES
• Greatest sequence variation between four different genotypes (base position changes between VP1/2A)
• Capsid proteins highly conserved, little genetic drift among strains
• Stability allows for common-source transmission by infected individuals as food handlers (uncooked shellfish)
• Transmission through fecal-oral route, replication in the liver
- Viraemia in high levels of HAV infected individuals – blood born (needles), sexual contact (oral/anal contact)
How is Hepatitis A treated?
• Goes away on its own – eat balanced meals, drink water; does not cause long term illness/ chronic liver damage
• Rare cases of liver infection (fulminant hepatitis) – inflammation of liver
• Antibodies against HAV produced upon infection (IgG and IgM)
- Clinical illness after a month of virus infection
- High levels of ALT (alanine transferase) enzyme in liver accumulates = biomarker
- IgG protects from subsequence reinfection, persists for entire life
Coxsackievirus
• Classification – picornaviridae, genus enterovirus, contain single +senseRNA, translate through same mechanism
• Distribution – worldwide
• Host – humans and chimpanzees (CA7 produce paralysis in monkeys)
- 23 serotypes of Coxsackie A virus (CA) – hand, food and mouth virus
- 6 serotypes of Coxsackie B virus (CB) – pericarditis, myocarditis, Bornholme Disease, etc (more serious)
• Epidemiology – present in environment (CB in waste waters, soils, shellfish) – major public health problem
- Spread through feces, contaminating environment – poorer the sanitation, higher contamination level
• Transmission and tissue tropism – same transmission route (oral via hands, water and food; aerosol from throat)
• Immune response – producing neutralizing antibodies IgA, IgM(result from silent infections and lifelong)
• Prevention and control – no prevention by vaccines currently but hygiene policy (hand washing, sanitary control
of pools and meals, bathing ins natural waters, shellfish, etc)
Apthovirus (ulcer)
• Veterinary disease (food and mouth disease (FMDV)) in tropics
• Infects cloven hoofed species (domestic animals)
• Extremely sensitive to acid inactivation – lower pH (6.8) gets rid of virus!
• Affects all major large animal livestock and wildlife (hard to control – reservoir)
• Sequential infection possible from different variants
• Highly contagious (rapid replication and short incubation, massive virus release, high susceptibility of host)
• Difficult to control and major internal trade issue (of livestock)
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Document Summary
Hepatoviruses: hepatitis a (hav) originally thought to be enterovirus but now known as unique genus of picornaviridae. Attracted to liver, absent vp4 protein, high thermostability. Viraemia in high levels of hav infected individuals blood born (needles), sexual contact (oral/anal contact) Clinical illness after a month of virus infection. High levels of alt (alanine transferase) enzyme in liver accumulates = biomarker. Igg protects from subsequence reinfection, persists for entire life. Coxsackievirus: classification picornaviridae, genus enterovirus, contain single +senserna, translate through same mechanism, distribution worldwide, host humans and chimpanzees (ca7 produce paralysis in monkeys) 23 serotypes of coxsackie a virus (ca) hand, food and mouth virus. 6 serotypes of coxsackie b virus (cb) pericarditis, myocarditis, bornholme disease, etc (more serious: epidemiology present in environment (cb in waste waters, soils, shellfish) major public health problem. Immune response producing neutralizing antibodies iga, igm(result from silent infections and lifelong) of pools and meals, bathing ins natural waters, shellfish, etc)
