96702063 virologi dasar
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VIROLOGI
INAYATI HABIB
Sifat-sifat Umum Virus
Penyebab infeksi terkecil, 20 - 300nm.
Genom: RNA atau DNA saja, terbungkus
protein, kadang dikelilingi membran lipid
di luar sel: virus non aktif ; replikasi pd sel
hidup disebut Parasit tk. Genetik/obligat
intraseluler
asam nukleat: informasi genetik agar sel
hospes msintesis makromolk.u/ virus baru
hospes beragam, inf pd org unisel/tk tinggi
Perbedaan Virus dg Mikroorganisme lain
Gambar Struktur Virus
Definisi bagian -bagian Virus
Kapsid: lapisan protein yg menutupi
genom asam nukleat
nukleokapsid: kapsid + asam nukleat
yang diselubungi
unit struktur: blok penyusun protein
dasar dari lapisan
kapsomer: unit morfologik pada
mikroskop elektron pada permukaan
partikel virus ikosahedral
Definisi Bagian-bagian Virus
Selubung : selaput mengandung lemak mengelilingi beberapa partikel virus
Virion : partikel virus lengkap, bbrp jenis sifatnya sama dg nukleokapsid
virus cacat: partikel virus secara fungsional kekurangan bbrp aspek replikasi
Gambar Morfologi Virus
FIVE BASIC STRUCTURAL FORMS OF
VIRUSES IN NATURE
• Naked icosahedral : e.g. poliovirus, adenovirus, hepatitis A virus
• Naked helical : e.g. tobacco mosaic virus. So far no human
viruses with this structure are known
• Enveloped icosahedral : e.g. herpes virus, yellow fever virus, rubella
virus
• Enveloped helical : e.g. rabies virus, influenza virus, parainfluenza
virus, mumps virus, measles virus
• Complex : e.g. poxvirus
Teori Evolusi Virus (2 hipotesis)
Virus berasal dari
komponen sel hospes
yang menjadi otonom
Komponen tersebut
menyerupai gen yang
telah mempunyai
kemampuan hidup
yang tidak tergantung
pada hospes.
Virus berasal dari sel
hidup yang bebas
Klasifikasi Virus
Jenis asam nukleat
ukuran dan morfologi
kerentanan thd pengaruh fisik dan kimiawi
adanya enzim khusus
sifat-sifat imunologik
metode penularan alami
inang, jaringan & tropisme sel
patologi, pembtk badan inklusi
simptomatologi
KLASIFIKASI VIRUS
PENYAKIT SISTEMIK
penyakit menyebar ke
seluruh tubuh mell.
aliran darah &
berpengaruh ke
berbagai organ.
Contoh:
Vaksinia,Campak,
Rubella,Cacar air,
demam kuning,
dengue, enterovirus
PENYAKIT PRIMER
Virus dpt mencapai
organ ttt melalui aliran
drh, saraf perifer / jalur
lain, predileksi di organ
tertentu
Klasifikasi berdsrkan
simptomatologi
kelemahannya: virus
yg sama sbbkan peny. berbeda ATAU peny.
sama disbb virus beda
PENYAKIT PRIMER
Peny. Sal. Nafas :
influenza, parainfluen,
pneumonia viral,
faringitis adenovirus
Peny. Mata:
konjungtivitis, herpes
Peny. Kulit/mukosa:
herp. simplek 1/oral &
2/genital, herp.zoster,
Peny. Ssn saraf:
Poliomyelitis,meningitis
, rabies.
Peny. Kelj. Ludah:
gondong , CMV
Peny. Sal.
Pencernaan:
rotavirus,adenovirus
enterik.
Peny. Hati: Hepatitis A,
B,C, demam kuning,
herpes, rubella
Peny. Lwt hub.
Sexual:
molusk.kontagiosum,
HSV 2, AIDS,hepatitis.
Klasifikasi berdasarkan sifat Biologi,
Kimia dan fisika
VIRUS DNA
Parvovirus, Papovirus,
Adenovirus,Herpes
virus, Pox virus,
Hepadna virus
VIRUS RNA
Picornavirus,
Kalisivirus, Reovirus,
Arbovirus,Togavirus
Flavivirus, Arenavirus,
Rabdovirus,Retrovirus
Bunyavirus,
Orthomiksovirus,param
iksovirus, Corona dan
Delta virus
Macam-macam VIRUS
INTERNATIONAL CLASSIFICATION OFVIRUSES
Primary characteristics used in classification
Viruses are classified according to the nature of their
genome and their structure
INTERNATIONAL CLASSIFICATION OFVIRUSES
Secondary characteristics
Replication strategy
Sometimes a group of viruses that seems to
be a single group by the above criteria is
found to contain a subgroup of viruses
which have a fundamentally different
replication strategy - in this case the group
will be divided based on the mode of
replication
Komposisi Virus
PROTEIN
Fx: transfer as.nukl ant
sel hospes, lindungi
genom virus, plekatan
dg sel hospes, struk.
partk. virus, tentukan
sifat antigenik virus
KARBOHIDRAT
glikoprotein, sbg Ag
ptg, pd permk punya
slbng u/ melekat virus
ASAM NUKLEAT
1 jenis as.nukleat
(DNA/RNA), informasi
genetik, genom untai
tunggal/ganda,lingkar/
untaian,segmen/tdk
LEMAK
Fosfolipid slbng virion,
virus mgd lemak peka
eter, kemamp infeksi
hilang
Rx Virus thd Agen Fisik & Kimia
PANAS & DINGIN
stabilitas bervariasi,
virus ikosahedral >
stabil, virus berslbng >
peka thd panas,
kemamp. inf hilang pd
50 - 60oC, 30 mnt, dpt
diawetkan pd suhu
dibwh titik beku (4oC),
virus berslbng: hilang
kemamp. inf setelah
penyimpanan lama
GARAM
pd garam 1 mol/L stabil, tetap aktif walau dipanaskan 1 jam 50oC, vaksin polio disimpan dlm dingin .
pH dan RADIASI
pH 5-9 stabil, enterovirus thn asam, virus hancur pd basa, nonaktif pd UV/sinar X
Rx Virus thd Agen Fisik & Kimia
DETERJEN
deterj. non ionik & Triton K100 melarutkan unsur
lemak pd slbng virus, SDS larutkan selubung &
memecah kapsid
FORMALDEHID
berx dg as. nukleat shg kemamp inf.hilang, genom
ganda > sulit dinonaktifkan formald.
ANTIBIOTIKA & ANTIBAKTERI LAIN
tdk berefek (alk.formalin,yod.), organik klor dosis >
tinggi dpt inaktifkan virus .
Agen Seperti Virus
VIROID
Molk.tunggal,RNA sirk.
tanpa selubung, RNA
kecil tdk mengkode
protein, peny. Tanamn.
VIRUS CACAT
As Nukleat & protein,
Replikasi butuh ‘virus
helper’, cacat oleh
karena mutasi/delesi
materi genetik.
PSEUDOVIRION
DNA sel hosp. mganti
DNA viral dlm kapsid
slm inf virus.dpt infek.
sel,tapi tdk replikasi.
PRION
Protein ,tanpa as. Nukl,
ME: filamen-2 = virus/
bakteri , resist. UV,
panas,formalin,nukleas
e, Inaktif pd otoklaf ,
hipoklorit & NaOH
PROSES PERTUMBUHAN VIRUS
Siklus Pertumbuhan dibagi 3 tahap:
tahap awal: penempelan, penetrasi,
pelepasan selubung
tahap tengah: ekspresi gena &
replikasi gena
tahap akhir: pengemasan dan
pelepasan virion
PROSES INFEKSI VIRUS
Pengenalan Sel Target
protein luar sebagai ‘reseptor binding
site’, yang berikatan dengan reseptor
protein spesifik pada permukaan sel
hospes
Penetration
The virus enters the cell in a variety of ways according to the nature of the virus.
Enveloped viruses
(A) Entry by fusing with the plasma membrane. Some enveloped viruses fuse directly with the plasma membrane. Thus, the internal components of the virion are immediately delivered to the cytoplasm of the cell (figure 1).
(B) Entry via endosomes at the cell surface (figure 2) Non-enveloped viruses
Non-enveloped viruses
may cross the plasma membrane directly or may be taken up into endosomes. They then cross (or destroy) the endosomal membrane.
Penetration
Fusion of a virus with the plasma
membrane after attachment to a
cell surface receptor
Figure A
Fusion of a virus with the
membrane of an endosome
Figure B
Penempel & Penetrasi Virion
Parental
Setelah menempel, penetrasi
membran plasma, melepas genom,
replikasi
Replikasi Genom dan Ekspresi
Gena
tahap 1: sintesis m RNA
tahap 2: tergantung asam nukleat virus
v. DNA: replikasi di nukleus (Poxvirus)
v. RNA: replikasi . di sitoplasma (kec
Influenza)
Pelepasan Virion
setelah matur, protein viral ditransport,
budding, insersi membran plasma
eksterna hospes
Release
Virus may be released due to cell lysis or if enveloped,may bud from the cell.
Budding viruses (figures 3 and 4) do not necessarily kill the cell.
Some budding viruses may be able to set up persistent infections.
Not all released viral particles are infectious. The ratio of non-infectious to infectious particles varies with the virus and the growth conditions.
Figure 3. Transmission electron
micrograph of HIV-1, budding and
free CDC
Figure 4. HIV budding from human
lymph tissue (TEM x133,335) ©
Dennis Kunkel Microscopy,
Inc. Used with permission
Transkripsi dan Replikasi Genom Virus
Tahap- tahap Replikasi Virus