Principles of Infection II
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What is the cell structure of the herpes simplex virus?
• virus has an envelope • 120 to 300 nm • nucleocapsid inside evenloped structure • tegument between nucleocapsid + envelope • virus has DNA
What is the name of the family of DNA viruses responsible for herpes infections?
Herpesviridae
How is herpes simplex virus type 1 transmitted?
Contact transmittion - from person to person, by sharing objects or even oral sex.
How is herpes simplex virus type 2 transmitted?
Transmitted by skin contact - usually sexually transmitted
What does more sexual partners suggest?
More likely to have antibodies to HSV2, but having a single sexual partner doesn’t mean you will not be infected.
When infected, do you ever clear the virus - what happens?
No, you have periods of latency - virus replication stops and then reactivation - release of latent virus.
What is the common figure for reccurences of the herpes virus?
1-5 per annum, some never have them, some have them frequently
Which virus causes chickenpox?
Varicella Zoster virus
Which virus causes glandular fever and how is it transmitted?
Epstein Barr virus - transmitted via saliva (kissing disease!)
What is the cellular structure of adenovirus, it’s transmission and impact?
• no envelope - dna virus • transmitted via contact • has different ‘serotypes’ -> causes eye/resp/GI infection
What is the cellular structure of papillomavirus, it’s transmission and impact?
• no envelope - DNA genome • horizontal (human to human) - sex involved • causes warts + cervical cancer
What is the structure of HIV?
• enveloped • RNA virus
What is the structure of rotavirus and its cause?
• non enveloped • small • causes diarrhoea
Which viruses are transmitted horizontally (human to human)?
• measles • mumps • adenovirus • influenza • ebola
What are some early symptoms of ebola infection?
• take 2-21 days to show • fever • headache • diarrhoea • vomiting, stomach/muscle pain • unexplained bleeding + bruising
What is the structure of ebola virus?
• RNA virus • enveloped
What is the pathophysiology of ebola (how it enters/impacts) and how is it transmitted?
• enters through mucuous membranes, breaks in skin, parenterally • infects many cell types • migrates from initial site to lymph nodes -> liver, spleen, adrenal • tissue necrosis + organ failure • inflammation • transmitted by direct contact with body fluids + contaminated objects (person to person)
How is rubella transmitted?
vertical (mother to foetus) mainly
Which diseases can be transmitted by insect bites and animal bites?
Insect bites: haemorrhagic fevers, yellow fever animal bites: rabies
What are some clinical factors of diagnosing infection?
• patient symptoms • duration of symptoms • have there been contacts with sources of infection • what is circulating in the population • location • lifestyle • other risk factors
What antibodies are looked for in an immunoassay?
IgM - recent infection IgG - past infection
Describe the method of culturing virus in cells
Human viruses need human cells to grow - takes 2-3 days, use light microscopy for cytopathic effect.
What is a quicker alternative with culturing virus in cells?
Look for viral proteins in cell cultures: - use immunofluorescence labelling method • use antibody directed against viral proteins • label antibody with immunofluorescence tag • you can see viral proteins
Describe the method of looking for RNA/DNA in the blood and how it can be amplified
• difficult to detect RNA/DNA as not enough in sample • use PCR to amplify nucleic acid • run it on a gel and see amplified product as a band