Post on 30-May-2018
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Some viruses are useful
Phage typing of bacteriaSome groups of bacteria,such as some Salmonella species,are classified into strains on the basis of the spectrum ofphages to which they are susceptible. Identification of thephage types of bacterial isolates can provide usefulepidemiological information during outbreaks of disease
caused by these bacteria.
Sources of enzymes.
A number of enzymes used in molecular biology are virusenzymes. Examples include reverse transcriptases from
retroviruses and RNA polymerases from phages.
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Pesticides. Some insect pests are
controlled with Anti-bacterial agents. In the mid-20th century
baculoviruses and myxoma virus has beenused to control rabbits.
Anti-bacterial agents. In the mid-20thcentury phages were used to treat somebacterial infections of humans. Interest
waned with the discovery of antibiotics, buthas been renewed with the emergence of
antibiotic-resistant strains of bacteria.
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Anti-cancer agents.
Genetically modified strains of modified viruses, such as herpes simplex virus
and vaccinia virus, are being investigated for treatment of cancers.These
strains have been modified so that they are able to infect and destroy specifictumour cells, but are unable to infect normal cells.
Gene vectors for protein production.
Viruses such as certain baculoviruses and adenoviruses are used as vectors totake genes into animal cells growing in culture. This technology can be used to
insert into cells genes encoding useful proteins, such as vaccine components,and the cells can then be used for mass production of the proteins.
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Merugikan
Pada tanamanTobacco Mosaic Virus
Potato Mosaic Virus
Hewan
Tetelo pada unggas : Newcastle Diseases VirusCacar pada sapi:Vaccinia virus
Manusia
Influenza : influenza virus
AIDS : Retrovirus
SARS: coronavirus
Flu Burung: Avian virus
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Shingles in an AIDS Patient
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STRUKTUR VIRUS
Struktur partikel Virusbervariasi:ukuran,bentuk dan susunan
kima
Sangat kecil ukuran berkisar 20 400 nm Virion:
Merupakan istilah teknis untuk satu
partikel virus lengkap yang tersusun dariasam nukleat dikelilingi protein
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Virus mempunyai DNA atau RNA di dalam protein
Capsid (Nucleocapsid)
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Structure of Influenza Virus
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Capsid:
Susunan protein yang mengelilingi genom
virus.
Mantel protein yang terdiri dari beberapa
subunit protein(Capsomer)
Pada beberpa virus kapsid ditutupi olehsampul (envelope) yang umumnya terdiri
dari lipid,protein dan karbohidrat Envelop
dapat ditutupi oleh struktur serupa paku(spike) yang merupakan kompleks
karbohidrat dan protein
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Morfologi Capsid:
Helical: protein mirip-pita membentuk spiral disekeliling asam
nukleat. Dapat kaku atau fleksibel. Tobacco mosaic virus
Ebola virus
Polyhedral: banyak sisi. Bentuk umum adalah icosahedron,dengan 20 muka segitiga dan 12 sudut
Poliovirus
Herpesvirus
Complex viruses: bentuk tidak teratur (umum)
Bacteriophages mempunyai serabut, lembaran, dan plat yang terikatcapsid
Poxviruses mempunyai beberapa selubung membungkus asam nukleat.
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Morphology of Herpesviruses
A. Schematic Representation B. Electron micrograph
B
Source: Virology 3rd edition, 1996
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Virus Bersampul
Berbentuk bulatJika virus heliks dan polihedral ditutupi
envelope, maka disebut virus heliks bersampul
(enveloped helical virus) atau virus polihedral
bersampul (enveloped polyhedral virus).
Contoh :
virus influenza (heliks bersampul),
virus herpes simpleks (polihedral bersampul
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Protein virus
Proteins that are components of virions areknown as structural proteins. They have to carry
out a wide range of functions, including
protection of the virus genome
attachment of the virion to a host cell (for
many viruses)
fusion of the virion envelope to a cell
membrane (for enveloped viruses).
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Virus proteins may have additional roles, some of
which may be carried out by structural proteins,
and some by non-structural proteins (proteinssynthesized by the virus in an infected cell but
they are not virion components). These additional
roles include
enzymes, e.g. protease, reverse transcriptase
transcription factors
primers for nucleic acid replication
interference with the immune response of thehost.
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Envelope virus
Envelope virus hewan biasanya muncul dari nukleusatau membran plasma inang, beruplipid dan
karbohidrat
Sedangkan envelope (protein) dikode oleh gen virus
dan keluar ke permukaan envelope sebagai spikesatau peplomers.
Spike dibutuhkan virus untukmenempel pada sel
inang
dapat untuk identifikasi
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Beberapa spike mempunyai:
Enzim neuroamidase
membantu virus dalam penetrasi ke dalam lap
epitelmukosa salurn pernapasan sel inang
Hemagglutinin
membalut/mengikat virion pada membran sel darahmerah dan menyebabkan hemaglutinasi
Glycoprotein
protein yang mempunyai karbohidrat
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Spike berperan pada proses pelekatanvirus pada sel inang.
Virus dengan kapsid yang tidak tertutup
oleh envelop disebut virus telanjang
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Material genetik :
The virion contains the genome of thevirus. Where as the genomes of cells are
composed of double stranded ,there are
four possibilities for a virus
double-stranded DNA (ds DNA)
single-stranded DNA (ss DNA)
double-stranded RNA (ds DNA)single-stranded RNA. (ss RNA)
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Tipe materi genetik virus:Materi genetik dapat untai tunggal atau ganda:
DNA untai tunggal (ssDNA):
Parvoviruses DNA untai ganda (dsDNA):
Herpesviruses Adenoviruses Poxviruses
Hepadnaviruses* (Partially double stranded) RNA untai tunggal (ssRNA): dapat plus (+) atau
minus (-) sense: Picornaviruses (+) Retroviruses (+)
Rhabdoviruses (-) RNA untai ganda (dsRNA):
Reoviruses
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Viruses
Cells
Hepatitis B virus 3.2
Approximate
genome size
(kbp DNA)
Phage 48.5
Mimivirus 1200
Mycoplasma genitalium 5800
Escherichia coli 4700
3200000Human
Genome sizes of some DNA viruses and cells.
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ss, circular
ds, linear
ss, linear
ds, circular
ss, circular
ds, linear
ss, linear
Examples
Parvoviruses
Poxviruses
Phage X174
Baculoviruses
Tobacco mosaic virus
Reoviruses
Hepatitis delta virus
DNA
genomes
RNA genomes
Linear and circular viral genomes.
ss: single-strandedds: double-stranded
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