Basic Virology

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Size :Virus size is ascertained by electron microscopy.Viruses range from 20 to 14,000 nm in length.

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Viruses and Bacteria ComparedBacteria Viruses

Typical Bacteria

Rickettsias/Chlamydias

Intracellular parasite No Yes YesPlasma membrane Yes Yes NoBinary fission Yes Yes NoPass through bacteriological filters No No/Yes YesPosses both DNA and RNA Yes Yes NoATP-generating metabolism Yes Yes/No NoRibosomes Yes Yes NoSensitive to antibiotics Yes Yes NoSensitive to interferon No No Yes

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Struktur virus

Deskripsi komposisi kimia dan struktur fisik dari enveloped dan nonenveloped virus

Nucleic acid :

Viruses mengandung DNA atau RNA (never both!!), single or double stranded, linear or circular

virion adalah partikel virus yang lengkap, berisi asam nukleat, dikelilingi lapisan protein (kapsid)

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Capsid and envelope :

Capsid : lapisan protein yg mengelilingi nucleic acid

capsid ada yang dilapisi envelope yang mengandung lipids, protein, carbohydrates.

Beberapa envelopes ada yang dilapisi carbohydrate-protein complexes disebut spikes.

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General morphology Helical viruses (i.e : Ebola virus) : long rods, capsids

berbentuk cylinders mengelilingi nucleic acid. Polyhedral viruses (i.e : adenovirus) : bentuk bermacam,

capsid berbentuk icosahedron

Helical virus Icosahedral virus

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Classification of viruses based on type of nucleic acid :

DNA containing viruses1. Adenovirus2. Herpesvirus :

• HSV-1 & HSV-2• Varicella zoster virus (VZV)• Cytomegalovirus• Epstein Barr virus

3. Parvovirus4. Poxvirus5. Hepadnavirus6. Papovavirus

• Papillomavirus• Polyomavirus

RNA containing viruses1. Picornavirus2. Arbovirus3. Togavirus4. Flavivirus5. Rotavirus6. Rhabdovirus7. Orthomyxovirus8. Paramyxovirus9. Viroid10.Coronavirus

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Classification virus berdasar cell tropism :

Enteric virus : rotavirus Hepatotropic virus : hepatitis virus Respiratoric virus : influenza virus Oncogenic virus : human papilloma virus Neurotropic virus: poliovirus Dermatotropic virus: herpes virus

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STRUKTUR SEL VIRUS :

Inti : DNA/RNA (Double stranded/single strand)

Kapsid: protein yang menyelubungi inti

Kapsomer: Unit nukleokapsid

Envelope: membran lipid

Virion: partikel virus komplit

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Detection of virus-infected cells :

Cytopathic effects (morphologic changes in the cells : cell lysis or necrosis, inclusion formation, giant cell formation, cytoplasmic vacuolization)

Appearance of virus-encoded protein (hemagglutinin)

Adsorption of erythrocytes to infected cells (hemadsorbtion)

Interference Morphologic transformation (loss of contact

inhibition) Viral growth in an embryonated chick egg (as

described previously)

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Reaksi terhadap physical & chemical agents

Heat & cold : viral inaktif dan rusak dengan heating 50oC-60oC selama 30’

Stabilisasi terhadap garam : virus stabil pada garam tertentu (MgCl2, MgSO4, Na2SO4)

pH : stabil pada pH 5.0 - 9.0 Radiation : UV dan X-ray inactivasi virus Detergents : merusak capsids Formaldehyde : merusak viral infectivity dengan

merusak nucleic acid Antibiotics : have no effect on viruses

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Viral multiplication1. Attachment (perlekatan)

2. Penetration

3. Uncoating

4. Biosynthesis of DNA/RNA viruses

5. Maturation and release

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Multiplication of DNA containing viruses

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Multiplication of RNA containing viruses

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Bacteriophage Virus yang menginfeksi

bakteri Fungsi :

Mempelajari virus Meneliti hubungan hospes-

parasit

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Life cycle of bacteriophage :

Lytic cycle

lytic cycle berakhir,dengan lysis dan death dari host cell

Lysogenic cycle

genom virus berintegrasi dengan genom bakteri. Bakteri mengalami perubahan fenotipik

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Type of viral infections :

Acute viral infections Persistent viral infections:

Chronic infections : virus dapat terus berada di hospes, dengan atau tanpa gejala klinis

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Laboratory diagnostic viral infections

Direct microscopic examination Virus culture Antigen detection Nucleic acid hybridization Serology

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Aphthousstomatitis Eczema

herpeticum Feverblister

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Congenital herpes disseminataCongenital herpes disseminata

Genital herpesGenital herpes

Herpetic whitlow