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Virus of Fungi, Yeast and Parasitic Microorganism. Anggota kelompok : Waode Nur Zara104070 30 Yunitazari Laksmi PW10407031 Venessa Alia 104070 32 Siti Amalia104070 33 Sutina104070 34 Vilandri Astarini10407035 Angga Kusnan Qodafi104070 36 Oktira Roka Aji10407038 - PowerPoint PPT Presentation
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Virus of Fungi, Yeast and Parasitic Microorganism.
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Anggota kelompok :
1.Waode Nur Zara104070302.Yunitazari Laksmi PW104070313.Venessa Alia104070324.Siti Amalia104070335.Sutina104070346.Vilandri Astarini104070357.Angga Kusnan Qodafi104070368.Oktira Roka Aji104070389.Noer Azizah1040703910.Anissa Kurnia M10407040
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VIRUS OF FUNGI
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Mycoviruses
• Mr. Hollings of Glasshouse Crop Research Institute, USA untuk pertamakalinya mendapatkan hasil eksperimen mengenai virus yang ditemukan pada jamur Agaricus bisporus yang menyebabkan “die-back disease” pada tahun 1962.
• Karakteristik yang paling umum dari “mushroom virus diseases” yaitu kerusakan pada panen dan kehiangan kemampuan untuk menghasilkan mycelium.
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Morphology of Mycoviruses • Bacilliform, rod-shaped, filamentous and herpes types. • Pada umumnya isodiametric dengan ukuran 25 and 50 nm
(diameter) dan berat partikelnya 6-13 x 106 dalton. • Memiliki double-stranded ribonucleic acid (dsRNA), biasanya
tersedmentasi menjadi 1-8 segments dengan total molekul 2 to 8.5 X 106 dalton.
• The dsRNA segments are separately enclosed into identical capsids.
• This feature of mycoviruses differentiates them from plant and animal dsRNA viruses in which the genetic material segments are, usually, all enclosed in a single virion.
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Mycoviruses
• Beberapa fungi penting yang mengandung Mycoviruses yaitu : – Agaricus bisporus (25-50 nm)– Alternaria tenius (30-40 nm),– Aspergillus foetidus (40-42 nm) – Penicillium brevicompactum (40 nm) – P.chrysogenum (35 nm), – P.funiculosum (25-30 nm) – P.notatum (25 nm), – Saccharomyces cerevisiae (40 nm).dll
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Double-stranded RNA (dsRNA) mycoviruses have been described for wide variety of fungi and plant-pathogenic fungi.
Three families based on number of genome segments, capsid structure, and nucleotide sequences :
Totiviruses : isometric dsRNA mycoviruses (nonenveloped isometric particles of 25 to 50 nm in diameter and typically cause latent infections in their host fungi), have a nonsegmented genome
Partitiviruses : isometric dsRNA mycoviruses, have segmented genomes.
Hypoviruses : can result in considerable morphological and physiological changes ( cytological alterations, changes in colony morphology and growth rate, and persistently attenuate novel virulence-related phenotypes (hypovirulence) , lack conventional virions and their dsRNAs are enclosed in host-encoded vesicles
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Effect of Mycovirus infection:
Morphological differences
dramatic changes in the fungal host, including slow growth, formation of colonies with abnormal, irregular margins, and a reduction in the number of viable asexual spores
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Isolatea dsRNA Morphologyb Colony diameter (cm)c
dsRNA-containing DK21 + Dark red, irregular 0.86 ± 0.25d
dsRNA-free DK21 − Pink, circular 2.34 ± 0.13
T-DK B2 + Dark red, irregular 1.01 ± 0.33d
T-DK C5 + Dark red, irregular 0.98 ± 0.51d
T-DK D1 + Dark red, irregular 0.88 ± 0.08d
T-DK F1 − Pink, circular 2.38 ± 0.04
Characteristics of dsRNA-containing and dsRNAfree isolates of DK21
* Fusarium graminearum isolates
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Effect of Mycovirus infection:
Change Pathogenicity• Hypovirulence or hypovirulence is a
phenomenon where the virulence of fungal pathogens is decreased, even lost, due to mycovirus infection.
• Reduced levels of virulence (hypovirulence) include suppressed sporulation, altered colony morphology, reduced pigmentation, increased oxalate accumulation, and altered cellulase and laccase activities.
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• mitovirus in Cryphonectria parasitica , Ophiostoma novo-ulmi , Sclerotinia homoeocarpa , Chalara elegans and Botrytis cinerea
• mycoreoviruses in Cryphonectria parasitica , and Rosellinia necatrix
• some unclassified mycoviruses, such as SsDRV in the family Flexiviridae in S. sclerotiorum , DaRV in Diarporthe ambigua , FgV-DK21 in Fusarium graminearum and a 33-nm isometric mycovirus in B. cinerea
Other mycoviruses causing hypovirulence or hypovirulence of plant fungal pathogens include:
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Transmission Mechanism
• The dsRNA could be cytoplasmically transmitted from one strain fungal host to another during hyphal fusion (anastomosis).
• Hypal fusion is defined as complete fussion of both wall and cytoplasm and thus is distinc frommere contact and adhesion of hypae
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Application
Mycovirus used as alternative control of fungal plant pathogen.
Problems associated with chemical control (fungicide): chemical does not arrive at the stems efficiently through heavy
canopy fungicide resistance of B. cinerea fungicide residues in plant produce environmental pollution.
Non-fungicidal alternatives such as Biological control are necessary and has attracted the interest of many researchers and has lead to discovery of new hypovirulent strains in other fungi
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Virus of Fungi
Family Genus Materi Genetik
unassigned Rhizidiovirus dsDNA
Chrysoviridae Chrysovirus dsRNA
Endornaviridae Endornavirus dsRNA
Hypoviridae Hypovirus dsRNA
PartiviridaePartitivirus dsRNA
Cryspovirus dsRNA
Reoviridae Mycoreovirus dsRNA
TotiviridaeTotivirus dsRNA
Victorivirus dsRNA
AlphaflexiviridaeBotrexvirus ssRNA
Sclerodarnavirus ssRNA
Gammaflexiviridae Mycoflexivirus ssRNA
NarnaviridaeNarnavirus ssRNA
Mitovirus ssRNA
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Virus of Fungi
Rhizidiovirus Virion • Virus capsid is not enveloped• Icosahedral symmetry.• The nucleocapsid is isometric• Diameter of 60 nm.
Host• Fungi• Hyphochytridiomycota
Spesies Rhizidiomyces virus (RZV)host : Rhizidiomyces sp.
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Virus of Fungi
Hypovirus
VirionNo true capsid. The dsRNA genome is encapsulated along with the viral replicase enzyme within host-derived lipid pleomorphic vesicles (50-80nm in diameter).
SpesiesCryphonectria hypovirus 1 (CHV-1) Cryphonectria hypovirus 2 (CHV-2)Cryphonectria hypovirus 3 (CHV-3)Cryphonectria hypovirus 4 (CHV-4)
HostCryphonetria parasiticaSclerotinia scleroliorum
Cryphonectria hypovirus 1 (CHV-1)
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Virus of Fungi
Partitivirus
VirionNon-enveloped icosahedric capsid, about 30-35 nm in diameterIcosahedric symmetry
Contoh : Atkinsonella hypoxylon virus (AhV)
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Virus of Fungi
Mycoreovirus Virion• Non enveloped• Icosahedral virion with a double capsid structure• About 80 nm in diameter
Spesiesmycoreovirus 1: Cryphonectria parasitica mycoreovirus-1 (CpMYRV-1) mycoreovirus 3: Rosellinia necatrix mycoreovirus-3 (RnMYRV-3)
Cryphonectria parasitica is a fungus that attacks primarily Castanea spp. but also has been known to cause damage to various Quercus spp
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VIRUS OF YEAST
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Virus of Yeast
Virus pada ragi Saccharomyces cerevisiae
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Virus of Yeast
Saccharomyces cerevisiae disebut “killer” karena membawa ds-RNA virus yang menyebabkan mereka dapat mensekresi sejumlah toksin yang bersifat letal untuk sel tertentu
Virus M1 (kategori M spesies) merupakan jenis double stranded RNA (ds-RNA) virus pada S.cerevisiae yang berukuran 1.7-2.1 kbp (lebih kecil dari L spesies yang berukuran 4.5)
Termasuk cytoplasmic viruslike particles (VLPs).
Saccharomyces cerevisiae killer virus M1 mengkode toksin K1 dan K28 yang spesifik untuk mekanisme imunitas
Saccharomyces cerevisiae killer virus M1
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Virus of Yeast
Saccharomyces cerevisiae killer virus M1
Produk protein inisial dari proses translasi M ds-RNA disebut prepotoksin. Target prepotoksin adalah secretory pathway dari yeast. Prepotoksin diproses untuk menghasilkan α/β dimer yang bertindak sebagai bentuk aktif dari toksin
Mekanisme Toksin K1:K1 berikatan dengan β-1,6-D-glucan receptor pada
dinding sel target masuk ke dalam sel berikatan dengan reseptor plasma membran Kre1p Membentuk kation-selektif channel ion pada membran yang bersifat letal pada sel
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Virus of Yeast
Saccharomyces cerevisiae killer virus M1
Mekanisme toksin K28:
K28 menggunakan reseptor α-1,6-mannoprotein untuk masuk ke dalam sel Toksin prekursor dapat diimpor ke retikulum enoplasma setelah diproses di RE, K28 pindah ke sitoplasma dan menghentikan sintesis DNA pada nukleus, meransang terjadinya apoptosis
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Virus of Yeast
Overview of the Killer Yeast
• Killer yeast = yeast (Saccharhomyces cereviseae) which carry a double stranded RNA virus.
• These viruses the yeast to secrete a number of toxic proteins which are lethal to receptive cells.
• These yeast cell are immune to the toxic effects of the protein due to an intrinsic immunity.
• Killer yeast strain can be a problem in commercial processing kill desirable strains.
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The Taxonomy of the Virus
Saccharomyces cerevisiae virus L-A
Virus classification:
Group: Group III (dsRNA)
Family: TotiviridaeGenus: Totiviru
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About the Virus
The virus discussed above = Saccharomyces cereviseae virus L-A. Icosahedral dsRNA virus.It has a single 4.6 kb genomic segments encodes is major coat
protein: Gag (76 kDa) and a Gag–Pol fusion protein (180 kDa) and several satellite double-stranded RNA sequences = M dsRNAs.
The genomic segment encodes:
a. the viral coat protein
b. protein which replicates the viral genomesThe M dsRNAs encodes:
a. secreted protein toxin (the Killer Toxin).
b. immunity to the toxin.
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More about the Killer Toxins
• The initial protein product from the translation of the M dsRNA = propotoxin.
• The toxin is targeted to the yeast secretory pathway.
• The toxin is processed and cleaved to produce an alpha/beta dimer active form of the toxin.
• The most studied variant toxins in S.cereviseae:
a. K1 : binds to the β-1,6-D-glucan receptor on the target cell wall, moves inside, and then binds to the plasma membrane receptor Kre1p. It forms a cation-selective ion channel in the membrane lethal to the cell.
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What’s Next About the Toxin?
b. K28 : uses the α-1,6-mannoprotein receptor to enter the cell, and utilizes the secretory pathway in reverse by displaying the endoplasmic reticulum HDEL signal. From the ER, K28 moves into the cytoplasm and shuts down DNA synthesis in the nucleus apoptosis.
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The Uses of the Toxins
Several experiments have made use of this to reliably indentify strains Morace, Archibusacci, Sestito and Polonelli (1984) used the toxins produced by 25 species of yeasts to differentiate between 112 pathogenic strains, based on their sensitivity to each toxin.
Used to control undesirable yeast Polonelli et al. (1994) used a killer yeast to vaccinate against C. albicans in rats.
Used as an antifungal agents Several experiments suggest that antibodies that mimic the biological activity of killer toxins have application as antifungal agents.
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5S RNA and tRNA-like Molecules Are Associated with Killer Virus
Killer virus ialah virus yang diturunkan (inherited) di sitoplasma pada sel-sel yeast (ragi).
Sel-sel yeast yang menjadi inang virus (killers) mensekresi suatu protein toxin yang lethal
(mematikan) terhadap sel-sel yang sensitif/tidak mengandung virus
Genom killer virus terdiri dari 2 segmen dsRNA yang terkapsidasi dalam sitoplasmik virion pada
sel-sel yang terinfeksi.
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Informasi genetik untuk toxin dan resistensi dikode pada M dsRNA (1830 bp) yang mendandung 200 bp AU-rich region. Segmen dsRNA lain, disebut LA (4980 bp) mengkode sebagian besar protein kapsid (M dan LA terkapsidasi).
Molekul dsRNA lain yang disebut LB dan LC terdapat di beberapa sitoplasma, baik killer maupun non-killer yeast.
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dsRNA virus pada S. cerevisiae terdiri dari 4.5 kb spesies L dan 1.7-2.1 kb spesies M, keduanya ditemukan pada partikel menyerupai virus di sitoplasma (viruslike particles/ VLPs).
Spesies L mengkode protein kapsidnya sendiri, dan LA mengkode capsid-polimerase fusion protein (cap-pol) yang diasumsikan menghasilkan VLPs dengan fungsi-fungsi replikase-transkriptase nya.
M1 dan M2 dsRNAs mengkode K1 dan K2 toxin serta fungsi dari replikasi.
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• This virus prevent growht of sensitive wild yeast srains
• Caused contamination of alcoholic fermentation. High volatile activity, H2S production, off-falvors caused by fusel oil,acetaldehyd, lactic acid
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Contoh ScV-L
- Simple double-stranded RNA
- -4,8 kbp RNA (L) encapsidated in isometric
- Have two desaperately dsRNAs,
- Larger is 4,9 kbp encodes the major capsid polypeptida
- Smaller dsRNA (M) is 1,9 kbp encodes a secreted polypeptide toxin (killer factory)
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VIRUS OF PARASITIC MICROORGANISM
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Apa itu Parasit?
• Parasit adalah organisme yang hidup pada inang untuk memperoleh nutrisi tanpa memberikan keuntungan pada inang tersebut. Bahkan cenderung merugikan pada inang.
• Beberapa contoh parasit diantaranya adalah protozoa, yeast, atau organisme multisellular lainnya seperti fungi atau cacing.
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Protozoa
• Protozoa merupakan hewan bersel tunggal, berinti banyak dan tidak memiliki dinding sel. Ukurannya antara 3-1000 mikron dan merupakan organisme mikroskopis bersifat heterotrof.
• Beberapa jenis protozoa bersifat parasit dan menyebabkan penyakit pada manusia dan hewan ternak.
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Penemuan Virus pada Protozoa
• Virus atau partikel seperti virus telah terobservasi pada beberapa protozoa, yaitu Leishmania, Entamoeba histolytica, Acanthamoeba sp., Naegleria, Plasmodium vivax, P. berghei, Paramecium aurelia, Carchesilun polypinum dan 19notocoma sabellarum.
• Pada strain tertentu Paramecium aurelia ditemukan adanya fenomena ‘pembunuh’ (killer) yang berkaitan dengan keberadaan sejumlah partikel yang disebut sebagai kappa di dalam sitoplasmanya.
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Kappa
• Status biologis kappa dan partikel terkait, telah lama menjadi
subjek investigasi intensif dan memunculkan banyak spekulasi.
• Kappa telah diamati sebagai elemen genetika endegenous, virus,
rickettsia, bakteri atau alga degenerasi. Bukti yang mendukung
bermacam sudut pandang sangat sedikit dan kebanyakan tidak
dapat dibuktikan.
• Sonneborn (1938) menyebut partikel infeksi, innterselular parasit,
menjadi manifestasi sebuah level organisasi protoseluler,yang
akan menentukan perbedaannya dari tipe bakteri.
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Membedakannya..
• Ukuran, sensitivitas pada antibotik, reproduksi dengan
pembelahan transverse dan keberadaan DNA dan RNA pada
partikel yang sama akan menjadikan mereka seperti rickettsia
atau bakteri.
• Sebaliknya, ketiadaan atau sedikitnya enzim dan kegagalan
pertumbuhan ekstraseluler akan membuat mereka seperti virus.
Konsentrasi DNA dan RNA pada Kappa dan partikel lambda sangat
mirip dan tidak dapat membedakan partikel ini dari bakteri.
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• Keberadaan kappa bergantung kepada gen kromosomal dominan K. Beberapa peneliti, seperti T.M. Sonneborn, mengamati bahwa sel P. aurelia yang mengandung partikel-partikel kappa akan menghasilkan senyawa beracun yang dapat mematikan strain-strain protozoa lainnya yang ada di sekitarnya. Senyawa beracun ini selanjutnya disebut sebagai paramesin, sedangkan partikel-partikel kappa ternyata merupakan bakteri simbion yang kemudian dikenal dengan nama Caedobacter taeniospiralis, yang artinya bakteri pembunuh berbentuk pita spiral.
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Kelas Kappa pada Paramecium
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Virus Taxonomy
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00.075.0.03.001. Leishmania brasiliensis virus 1-1
Name, Synonyms and Lineage
Synonym(s): Leishmania RNA virus-1. ICTV approved acronym: LRV1- 1. Virus is the type species of the genus Leishmaniavirus; family 00.075. Totiviridae.
ICTVdB Virus Code: 00.075.0.03.001. Virus accession number: 75003001. Obsolete virus code: 75.0.3.0.001; superceded accession number: 75030001. NCBI Taxon Identifier NCBI Taxonomy ID: 58103.
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Virion Properties Leishmania brasiliensis virus 1-1
• Morphology
Virions consist of a capsid. Virus capsid is not enveloped, round with icosahedral symmetry. The isometric capsid has a diameter of 33 nm.
• Nucleic Acid
The genome is monopartite, only one particle size is recovered of linear, double-stranded RNA. The complete genome is 5284 nucleotides long, is fully sequenced. Sequence has the accession number [M92355]. The 5'-end of the genome does not have cap. GenBank records for nucleotide sequences; complete genome sequences.
• Proteins
The viral genome encodes structural proteins and non-structural proteins.
• Lipids
Lipids are not reported.
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Biological Properties Leishmania brasiliensis virus 1-1
Natural Host
• Domain Viral hosts belong to the Domain Eucarya.
• Domain Eucarya Kingdom Protoctistae.
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Giardia lamblia
Giardia lamblia adalah protozoa penyebab giardiasis, mengganggu pencernaan, dengan
berdiam di usus. Menginfeksi dengan membentuk cyst pada saluran pencernaan dan menyebabkan
diare.
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00.075.0.02.001. Giardia lamblia virus
Name, Synonyms and Lineage
ICTV approved acronym: GLV. Virus is the type of the genus 00.075.0.02. Giardiavirus; of the family 00.075. Totiviridae.
CTVdB Virus Code: 00.075.0.02.001. Virus accession number: 75002001. Obsolete virus code: 75.0.2.0.001; superceded accession number: 75020001. NCBI Taxon Identifier NCBI Taxonomy ID: 29255.
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Virion PropertiesGiardia lamblia virus
• Morphology
Virions consist of a capsid. Virus capsid is not enveloped, round with icosahedral symmetry. The isometric capsid has a diameter of 36 nm.
• Nucleic Acid
The genome is monopartite, only one particle size is recovered of linear, double-stranded RNA. The complete genome is 7000 nucleotides long, is fully sequenced. Sequence has the accession number [L13218]. The 5'-end of the genome does not have cap. GenBank records for nucleotide sequences; complete genome sequences.
• Proteins
The viral genome encodes structural proteins and non-structural proteins.
• Lipids
Lipids are not reported.
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Biological Properties Giardia lamblia virus
Natural Host
• Domain Viral hosts belong to the Domain Eucarya.
• Domain Eucarya Kingdom Protoctistae.
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Infection
GLV not causes apparent growth inhibition infected cell.
Subtle morphological and celuller changes evident within the host cells during virus infection have not been characterized.
When used purified GLV to infect virus-free trophozoites:
• Virus-like particles are confirmed to certain vesicles by a double-layered membrane in cytoplasm during early infection
• Spread to the cytoplasm in heavily infected cell later.
• GLV enter nuclei and produce profound changes in the nuclear structural in the late phase infection.
• Provide a detailed insight into virus replication and transportation associated with the cytosolic fraction are empty.
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Acanthamoeba polyphaga
•Acanthamoeba is pathogenic to humans causing a rare but fatal encephalitis (infection of the brain) in the immunocompromised host and, more frequently, a potentially blinding infection of the cornea (keratitis). •Prior to 1980's, amoebae had been reported from eye (ocular) infections only rarely - these cases were associated with trauma to the eye.• In mid 1980's cases began to occur in wearers of contact lenses. Contact lens wearers are most at risk from acanthamoeba keratitis and account for 95% of reported cases. •Poor hygiene practices such as failing to clean and disinfect lenses and rinsing them in tap water are known risk factors.
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00.110.0.01.001. Acanthamoeba polyphaga mimivirus
Name, Synonyms and Lineage
Misnomer Bradfordcoccus in use until identified as virus. Virus is assigned to the genus 00.110.0.01. Mimivirus; presently not assigned to a family.
ICTVdB Virus Code: 00.110.0.01.001. Virus accession number: 11001001. NCBI Taxonomy ID: 212035.
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Virion Properties Acanthamoeba polyphaga mimivirus
• Introduction
Size and shape of virus has been determined by electron microscopy.
• Morphology
Virions consist of a capsid and fibrils. Virus capsid is not enveloped. Virions resemble small Gram-positive cocci when Gram stained. Capsid is spherical and exhibits icosahedral symmetry. The isometric capsid has a diameter of 300–400 nm. The capsid shells of virions are composed of multiple layers. Capsids appear hexagonal in outline. Evenly dispersed surface projections are distinct fibrils. The length of fibers is 80 nm.
• Physicochemical and Physical Properties
Virions have a buoyant density in CsCl of about 1.36 g cm–3.
.
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Virion Properties (2) Acanthamoeba polyphaga mimivirus
• Nucleic Acid
The genome is not segmented and contains a single molecule of circular double-stranded DNA. Complete sequence is 1181404 nucleotides long, has the accession number [AY653733] and encodes 1262 genes. NCBI reference genome accession number is [NC_006450].
• Lipids
Lipids are absent.
• Carbohydrates
Carbohydrates are not found in virions
• Antigenicity
Antigenic determinants may be found on virion surfaces that correspond to 35 KDa polypeptide. Antigenic specificity of the virion can be determined by immunoblotting test.
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Biological Properties Acanthamoeba polyphaga mimivirus
• Natural Host Range
Viral hosts belong to the Domain Eucarya. Domain Eucarya Kingdom Protoctistae.
• Kingdom Protoctista
Division Amoebozoa.
• Host Classification
VVirus infects Family Amboebidae; Acanthamoeba polyphaga.
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Daftar Pustaka
• Anonim 1, 2009. Hygiene - Viruses, Bacteria, and Parasites.http://www.scientificpsychic.com-health-hygiene.html. Tanggal Akses : 6 November 2009.
• Anonim 2, 2009. Protozoa. . http://www.e-dukasi.net/mol/mo_full.php?http://www.e-dukasi.net/mol/mo_full.php?moid=134&fname=bio_106_kb1_hal5.htmmoid=134&fname=bio_106_kb1_hal5.htm. Tanggal Akses : 7 November 2009.
• Anonim 3, 2009. Viruses in Protozoa. http://www.microbiologyprocedure.com/virus-structure-and-http://www.microbiologyprocedure.com/virus-structure-and-classification/viruses-in-protozoa.htmclassification/viruses-in-protozoa.htm. Tanggal Akses : 7 November 2009.
• ICTVdB Management (2006). 00.075.0.02.001. Giardia lamblia virus. In: ICTVdB - The Universal Virus Database, version 4. Büchen-Osmond, C. (Ed), Columbia University, New York, USA
• Büchen-Osmond, C. (Ed) (2006). 00.110.0.01.001. Acanthamoeba polyphaga mimivirus. In: ICTVdB - The Universal Virus Database, version 4. ICTVdB Management, Columbia University, New York, USA
• ICTVdB Management (2006). 00.075.0.03.001. Leishmania brasiliensis virus 1-1. In: ICTVdB - The Universal Virus Database, version 4. Büchen-Osmond, C. (Ed), Columbia University, New York, USA
• SONNEBORN, T. M. (1938). Mating types, toxic interactions and heredity in Paramecium aurelia. Science, N.Y. 88, 503
• W. J. Van Wagtendonk, Jo Ann D. Clark and G. A. Godoy, 1963 National Academy of Sciences
• Zaifbio, 2009. Sterilitas Jantan pada Jagung. http://zaifbio.wordpress.com/2009/11/01/sterilitas-jantan-http://zaifbio.wordpress.com/2009/11/01/sterilitas-jantan-pada-jagung/. pada-jagung/. Tanggal Akses : 7 November 2009.
• http://www.esrf.eu/events/Seminars/chantal-abergel-18september2009
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Anonim 1, 2009. Virus-like particle. http://en.wikipedia.org/wiki/Virus-like_particle (8 Novembr 2009)Anonim 2, 2009. Viral Zone. http://www.expasy.ch/viralzone/all_by_protein/230.html. (8 Novembr 2009)Fauquet,C. 2009. Virus taxonomy: classification and nomenclature of viruses. Academic Press.Schmitt, M.J. and D J Tipper, 1990, K28, a unique double-stranded RNA killer virus of Saccharomyces cerevisiae. http://mcb.asm.org/cgi/content/abstract/10/9/4807 (8 November 2009)
