Virus family basic factfile (Year 2)

Question 1

Poxviruses (Poxviridae)

Answer 1

• Baltimore Grp 1, 2 subfamilies = Chordopoxvirinae + Entomopoxvirinae
• Has oval/brick-shaped particles (200-400nm long)
• External surface is ridged in parallel rows, sometimes arranged helically
• Detailed structure still isn’t fully clear
• > 100 virus-encoded proteins arranged in external + internal structures
• Resistant to degradation + can survive in environment for a long time
• Linear dsDNA genome of 130-375kb, encodes ~200 proteins

Question 2

Papillomaviruses (Papillomaviridae)

Answer 2

• Baltimore Grp 1, 53 different genera in Papillomaviridae
• Strict host + tissue specificity
• > 200 strains of HPV
• Icosahedral non-enveloped
• 60nm in diameter, composed of 72 pentamers
• Circular dsDNA, ~8kb, episomal, encodes 7 non-strcutural proteins (E1-E7, except E3) + 2 structural proteins (L1 +L2)
• Packaged in virion with cellular histones, overlapping reading frames all on the same strand
• Has cis-regulatory elements

Question 3

Picornaviruses (Picornaviridae)

Answer 3

• Baltimore Grp 4, very big family, Vin Diesel would be jealous
• 7-8kb genome approx.
• 20-30nm in size, icosahedral non-enveloped
• +tive sense ssRNA, non-segmented, uncapped 5’ + polyadenylated 3’, also contains 5’ + 3’ NTRs (ends) that have highly ordered RNA structures
• Single ORF, genome divided into 3 segments
• Genome structure/segments tend to vary between picronavirus species as well as initiation complexes in translation

Question 4

Flaviviruses (Flaviviridae)

Answer 4

• Baltimore Grp 4, currently 89 species in 4 genera
• +tive sense ssRNA, 9-13 kb genome structure
• 5’ cap or IRES depending on genus, no 3’ polyA tract
• Single ORF
• Flaviviruses in flavivirus genus are arthropod-borne

Question 5

Coronaviruses (Coronaviridae)

Answer 5

• Baltimore Grp 4, prior to 2020 had 4 common human coronaviruses, but 3 recently emerged zoonotic
• Speherical particles, 120nm in diameter
• +tive sense ssRNA, 28-32kb packaged in helical nucleocapsid
• 5’ cap, 5’+3’ UTR + 3’ polyA tail
• Transcriptional Regulatory Sequences (TRS) required for production of subgenomic mRNAs
• Enveloped with spike proteins, envelope proteins + matrix proteins

Question 6

Filoviridae

Answer 6

• Part of mononegavirales order
• Filamentous, ~80nm in diameter (Longer viral size in Marburg (790nm long) + Ebola (970nm))
• 18-19kb genome size, 7 proteins encoded

Question 7

Paramyxoviridae

Answer 7

• Spherical, ~150nm diameter
• 15kb genome, 8 proteins encoded,
• Includes measles + mumps

Question 8

Pneumoviridae

Answer 8

• Spherical, 150nm approx
• 15kb genome, 11 proteins encoded
• Includes RSV
• SImlar to paramyxoviridae, we differentiate them genetically

Question 9

Rhabdoviridae

Answer 9

• Bullet shaped, 180nm long x 75nm wide

- Includes Rabies virus (has -tive ssRNA (Grp 5), 11-15kb genome, 180x70nm, bullet-shaped enveloped, diverse host range)