Viral Infections in Childhood Flashcards

1
Q

Virion

A

An entire virus particle, consisting of an outer protein shell called a capsid and an inner core of nucleic acid (either ribonucleic or deoxyribonucleic acid—RNA or DNA)
Nucleic acid
Protein coat (capsid)
+/- envelope

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2
Q

Nucleocapsid

A

Nucleic acid + protein coat

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3
Q

Viral nucleic acid

A

Double stranded DNA
(single stranded DNA in parvovirus)
Single stranded RNA (+ or - polarity)
(double stranded RNA in reoviruses)

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4
Q

Viruses as intracellular parasites

A

Dependent on cells they infect for energy, metabolic intermediates and most enzymes

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5
Q

Steps in Viral Life Cycle

A
Attachment
Entry
Uncoating
Synthesis of Viral Components
Assembly + release
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6
Q

Step 1: Viral attachment

A

Binding sites on the virus
Receptors (+/- co-receptors) on plasma membrane of cell
“cell tropism”
Cell must be permissive (have all the right intracellular components required by the virus to replicate

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7
Q

Step 2: Entry

A

Takes from seconds to several minutes
Enveloped viruses undergo membrane fusion
May undergo receptor-mediated endocytosis

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8
Q

Step 3: Uncoating

A

Can take place in:
–> endosome (receptor mediated endocytosis), due to low pH and lysosomal enzymes
–> cytosol
–> nuclear membrane
Results in transport to right part of cell to begin new virion production

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9
Q

Step 4: Synthesis of viral components

A

Requires viral mRNA to enable viral polypeptides and nucleic acid to be synthesised by cell machinery
DNA viruses that enter the nucleus can use only cellular enzymes
All other viruses must synthesise their viral mRNA
May carry their own enzymes (e.g. RNA polymerase, reverse transcriptase)

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10
Q

Step 5: Assembly + release

A

After synthesis of viral proteins + nucleic acid, virions assembled
Released by cell lysis + budding

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11
Q

Important Enveloped DNA viruses

A

Herpes Viruses
–> herpes simplex, varicella zoster, CMV, Epstein-barr, HHV 6/7/8
Hep B
Poxviruses

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12
Q

Important Non-Enveloped DNA viruses

A

Papillomavirus
Adenovirus
Parvovirus (ssDNA)

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13
Q

Disseminated Herpes simplex virus in neonates

A

Sepsis-like syndrome
Hepatitis, coagulopathy
High mortality
IV aciclovir

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14
Q

HSV encephalitis

A

Fever
Seizures
Haemorrhagic infarction of white matter + cortex

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15
Q

Cytomegalovirus

A

Self-limiting illness

Severe disease in immunosuppressed

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16
Q

Congenital CMV

A

Commonest congenital infection in developed countries

Long term hearing deficit and neuro-developmental delay

17
Q

Congenital CMV Treatment

A

IV ganciclovir or oral valganciclovir- inhibits DNA synthesis
6 months treatment reduces hearing loss + improves neurodevelopment

18
Q

Chickenpox in adults

A

Generally more severe than children
Pneumonitis
Particularly severe in pregnant women

19
Q

Epstein-Barr virus

A
Spread by saliva
Infectious mononucleosis (glandular fever), typically 15-25 years old
20
Q

Burkitt’s lymphoma

A

Africa

EBV infection at early age

21
Q

EBV impact

A

Lymphoma in children + adults with advanced HIV disease

Post-transplant lymphoproliferative disease

22
Q

HHV-6 and 7: Roseola infantum

A

AKA Exanthem subitem
Common 6 months-2yrs
Sudden onset of high fever, lasts few days then stops, rash appears

23
Q

Consequence Hep B Chronic infection

A

Cirrhosis

Hepatocellular carcinoma

24
Q

Hep B mother to child

A
Risk of transmission
--> eAg-negative 10-20%
--> eAG-positive 90%
Reduced to <5% with interventions at birth
Vaccine +/- HBIG
25
Q

Molluscum contagiosum

A

Normal host- moist areas, direct contact, mild but persist several years
Immunosuppressed- severe

26
Q

Papillomavirus

A

Cause of cervical cancer
Serotypes 16 + 18 carcinogenic
Serotypes 6 + 11 genital wart

27
Q

Papillomavirus vaccines

A

Cervarix- 16,18

Gardasil- 6, 11, 16, 18

28
Q

Adenovirus

A

URTI/pneumonia
Conjunctivitis
Diarrhoea
Disseminated disease in immunocompromised hosts

29
Q

Parvovirus B19

A

Attaches to blood group P antigen
If people lack P antigen, not susceptible
Replicates in rapidly dividing cells (red cell precursors)–> in people with haematological problems, leads to aplastic crisis

30
Q

Parvovirus B19 symptoms

A
Asymptomatic
"slapped cheek" syndrome
Arthropathy
Aplastic crisis
Foetal loss
31
Q

Important Enveloped RNA virus

A

Measles, mumps, rubella
RSV, influenza, parainfluenza
Hep C
HIV

32
Q

Important non-enveloped RNA virus

A

Rotavirus
Enteroviruses
Hep A

33
Q

Measles

A
Fever
Cough
Conjunctivitis
Miserable
Koplik spots
Rash
Subacute sclerosing pan-encephalitis
34
Q

Congenital Rubella

A

Eyes- cataracts, micro-ophthalmia, glaucoma
Ears- sensorineural deafness
Heart- pulm artery stenosis, VSD
Low birth weight, rash, microcephaly

35
Q

Bronchiolitis

A
70% RSV
Inflammation of bronchioles
Cough
Resp. distress
Wheeze
Palivizumab (monoclonal Ab) for prevention
36
Q

Oral Rotavirus vaccines

A

RotaTeq

RotaRix