B.Sc: Biology / Medical Analysis / Jor. M.Sc.: Medical Microbiology / Jor

B.Sc: Biology / Medical Analysis /

Jor. M.Sc.: Medical Microbiology / Jor. Ph.D.: Medical Virology & Serology /

UK

Prof. Mamdoh Harahsha

INTRODUCTIONINTRODUCTION

• SmallSmall

• Dependent on living cellsDependent on living cells

• GenomeGenome

• Have receptor-binding proteinHave receptor-binding protein

Comparing the size of a virus, a Comparing the size of a virus, a bacterium, and an animal cellbacterium, and an animal cell

0.25 m

Virus

Animalcell

Bacterium

Animal cell nucleus

Size of virusesSize of viruses

Basic components of virusesBasic components of viruses

Virion (Intact virus):Virion (Intact virus):

• Capsid (capsomeres)Capsid (capsomeres)

• Nucleic acidNucleic acid

Both Both Nucleocapsid Nucleocapsid

# Envelope# Envelope

Influenza virusInfluenza virus

Virus symmetry Virus symmetry (Nucleocapsid)(Nucleocapsid)

• IcosahedralIcosahedral

• HelicalHelical

• ComplexComplex

Capsid and CapsomeresCapsid and Capsomeres

Helical Helical

IcosahedralIcosahedral

ComplexComplex

Electron MicroscopyElectron Microscopy

Virus Virus genomesgenomes

• # All DNA viruses ds # All DNA viruses ds EXCEPTEXCEPT

ParvoviridaeParvoviridae

• # All RNA viruses ss # All RNA viruses ss EXCEPTEXCEPT

ReoviridaeReoviridae

• # Positive & Negative stranded RNA# Positive & Negative stranded RNA

• # Exons & introns# Exons & introns

Virus genome & transcriptional Virus genome & transcriptional mapsmapsDNA virusesDNA viruses

• Herpes & PoxvirusHerpes & Poxvirus

150 genes 150 genes No splicing No splicing

(Large No. of genes)(Large No. of genes)

• AdenovirusAdenovirus

30 genes 30 genes Viral Viral splicing splicing

• ParvovirusParvovirus

Few genes Few genes Viral Viral splicingsplicing

RNA virusesRNA viruses

• Poliovirus: Poliovirus: +ve ssRNA+ve ssRNA

• Rabies: Rabies: -ve ssRNA-ve ssRNA

• Coronavirus: Coronavirus: +ve ssRNA+ve ssRNA

Classification of VirusesClassification of Viruses

• NA: NA: DNA OR RNADNA OR RNA• Number of strands of NA: Number of strands of NA: ds ds

or ss, or ss, • Forms: Linear, Circular, Forms: Linear, Circular,

Continuous (or circular with Continuous (or circular with breaks as in HBV), or Segmentedbreaks as in HBV), or Segmented

• PolarityPolarity• Symmetry of NASymmetry of NA• EnvelopeEnvelope

Nomenclature of virusesNomenclature of viruses

• Family:Family: --- viridae --- viridae

((AdenoviridiaeAdenoviridiae))

• SubfamilySubfamily --- Virinae--- Virinae

((AdenovirinaeAdenovirinae))

• Genera: Genera: --- virus--- virus(Adenovirus)(Adenovirus)

• Serotype: Serotype: --- Nnumber or letter--- Nnumber or letter

DNA VIRUSESDNA VIRUSES

• Poxvirus:Poxvirus: (Pox : pock or pustule)(Pox : pock or pustule)

• Herpesvirus:Herpesvirus: (Herpes : creeping)(Herpes : creeping)

• Adenovirus:Adenovirus: (Adeno : gland)(Adeno : gland)

• Hepadnavirus: Hepadnavirus: (Hepa : liver, dna: DNA)(Hepa : liver, dna: DNA)

• Papovavirus:Papovavirus: (Pa: papilloma, (Pa: papilloma,

Po: polyoma, Va: vacuolating Po: polyoma, Va: vacuolating agent)agent)

• Parvovirus: Parvovirus: (Parvus: small)(Parvus: small)

RNA VIRUSESRNA VIRUSES• Orthomyxovirus, paramyxovirusOrthomyxovirus, paramyxovirus

(Myxo: mucus)(Myxo: mucus)

• Rhabdovirus: Rhabdovirus: (Rhabdos: rod)(Rhabdos: rod)

• Picornavirus:Picornavirus: (Pico: small, (Pico: small, rna:rna:

RNA)RNA)

• Togavirus: Togavirus: (Toga: cloak)(Toga: cloak)

• Flavivirus: Flavivirus: (Flavi: yellow)(Flavi: yellow)

• Reovirus: Reovirus: (R: respiratory, E: (R: respiratory, E:

enteric, O: orphan)enteric, O: orphan)

• Arenavirus: Arenavirus: (Arena: sand)(Arena: sand)

• Retrovirus: Retrovirus: (Re: reverse, (Re: reverse, TR: TR: transcriptase)transcriptase)

• Calicivirus: Calicivirus: (Calix: cup)(Calix: cup)

• Coronavirus: Coronavirus: (Corona: Crown)(Corona: Crown)

Morphology of VirusesMorphology of Viruses

Family name Genome Positive or negative stranded genome

Infectivity of isolated nucleic acid

Polymerase or transcriptase present in virion

Approx. genome size

DNA viruses

Parvoviridae ss +- + None 5

Papovairidae ds +- + None 8

Adenoviridae ds +- + None 36

Herpesviridae ds +- + None 150

Poxviridae ds +- - DNA-RNA 150

Hepadnaviridae ds +- ? DNA-RNA 3

RNA viruses

Astroviridae ss + + None v8

Picornaviridae ss + + None 8

Flaviviridae ss + + None 10

Togaviridae ss + + None 12

Coronaviridae ss + + None 30

Bunyaviridae ss - - RNA-RNA 16

Orthomyxoviridae ss - - RNA-RNA 13

Paramyxoviridae ss - - RNA-RNA 15

Rhabdoviridae ss - - RNA-RNA 15

Arenaviridae ss - - RNA-RNA 12

Retroviridae ss + - RNA-DNA 10

Reoviridae ds - - RNA-RNA 20

Filoviridae ss - - RNA-RNA 12

Caliciviridae ss + ? None 8

Family name Representative viruses Approximate diameter of virion (nm)

Symmetry of of nucleocapsid

DNA viruses

Parvoviridae Human parvovirus 20 I

Papovaviridae Wart viruses 50 I

Adenoviridae Adenoviruses 80 I

Herpesviridae Herpes simplex viruses 180 I

Poxviridae Vaccinia virus 250 C

Hepadnaviridae Hepatitis B virus 40 I

RNA viruses

Astroviridae 30 I

Picornaviridae Polioviruses 25 I

Flaviviridae Yellow fever virus 30 I

Togaviridae Rubella virus 80 I

Coronaviridae Infectious bronchitis virus 100 H

Bunyaviridae California encephalitis virus 100 H

Orthomyxoviridae Influenza viruses 100 H

Paramyxoviridae Measles virus 150 H

Rhabdoviridae Rabies virus 150 H

Arenaviridae Lassa fever virus 100 H

Retroviridae HIV-1 100 I

Reoviridae Rotaviruses 70 I

Filoviridae Marburg virus Variable H

Caliciviridae Calicivirus 35 I