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