basic virology
DESCRIPTION
parasitologiTRANSCRIPT
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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