I will concentrate on families/genera of viruses that have human pathogens. Drawings and info from ICTV and Strauss J. Viruses and Human Disease 2002

I. Positive sense Single-Stranded RNA viruses(ssRNA +)

1. Picornaviridae

A. Name – pico = small

B. Structure – non-enveloped, iscohedral, T=3, diameter is 30nm

C. Genome

i. positive sense single-stranded RNA (like mRNA)

ii. ~7500 bp

iii. contains one open reading fame

D. Message

i. 3’ poly-A

ii. cap independent (IRES)

E. Genera

i. Enteroviruses

a. Poliovirus – aseptic meningitis, paralysis

b. Coxsackie virus – common cold, myocarditis

c. Human Enterovirus – aseptic meningitis, conjunctivitis

d. Echovirus - aseptic meningitis, paralysis, encephalitis

ii. Parechoviruses

a. Human parechovirus – gastroenteritis

iii. Rhinoviruses

a. Human rhinovirus – common cold

iv. Kobuviruses

a. Aichi Virus – gastroenteritis

v. Hepatoviruses

a. Hepatitis A – hepatitis

2. Caliciviridae

A. Name – Latin for “cup”. So named because of the cup appearance under the electron microscope

B. Structure - non-enveloped, iscohedral, diameter is 30nm

C. Genome

i. positive sense single-stranded RNA (like mRNA)

ii. ~8000 bp

iii. contains three open reading fames

D. Genera

i. Norwalk-like viruses

a. Norwalk virus – epidemic gastroenteritis

ii. Sapporo-like viruses

a. Sapporo virus - epidemic gastroenteritis

3. Astroviridae

A. Name – Greek for “star”. So named because of the star-like appearance under the electron microscope

B. Structure - non-enveloped, iscohedral, diameter is 30nm

C. Genome

i. positive sense single-stranded RNA (like mRNA)

ii. ~7000 bp

iii. contains two open reading fames and one ribosomal frameshifting sequence.

D. Genera

i. Astroviruses

a. Human astrovirus – gastroenteritis

4. Togaviridae

A. Name – Latin for “cloak”. So named because they are enveloped.

B. Structure – enveloped, icosohedral, diameter is 70-50nm

C. Genome

i. positive sense single-stranded RNA (like mRNA)

ii. ~10000 - 12000 bp

iii. genome contains a 5’ cap

D. Message

i. 3’ poly-A

ii. cap dependent

E. Genera

i. Alphaviruses – arboiviruses ( arthropod borne viruses)

a. Chikungunya virus – arthralgia, fever

b. Eastern equine encephalitis virus – encephalitis

c. Western equine encephalitis virus - encephalitis

ii. Rubiviruses

a. Rubella virus – rash, congenital abnormalities

5. Flaviviridae

A. Name – flavus is Latin for “yellow”. So named because of yellow fever caused by yellow fever virus.

B. Structure – enveloped, icosohedral, diameter is 60-40nm

C. Genome

i. positive sense single-stranded RNA (like mRNA)

ii. 1, 12.3, and 9.6 kb for flavi-, pesti-, and hepaciviruses, respectively.

iii. flavi- genus has a 5’ capped genome.

D. Message

i. flavi- genus translation is cap-dependant but lacks 3’ poly A tail

ii. pesti-, hepaci- genera id cap-independent (IRES) and lacks 3’ poly A tail.

E. Genera

i. Flaviviruses - arboiviruses ( arthropod borne viruses)

a. Dengue fever virus – dengue fever, shock, hemorrhage

b. Yellow fever virus – yellow fever, hemorrhage, liver distruction

c. Japanese encephalitis virus-like viruses

1. Japanese encephalitis virus – encephalitis

2. St. Louis encephalitits virus – encephalitis

3. Murray valley encephalitis virus – encephalitis

4. Tick borne encephalitis virus – encephalitis

5. West Nile virus – encephalitis

ii. Hepaciviruses

a. Hepatitis C virus – hepatitis, liver cancer

6. Coronaviridae

A. Name–corona is Latin for “crown”. So named because of the array of long spikes on the viral envelope

B. Structure – enveloped, icosohedral core, 120-160nm

C. Genome

i. positive sense single-stranded RNA (like mRNA)

ii. ~28 - 31 kbp

iii. genome contains a 5’ cap and a 3’ poly A tail

D. Message

i. The genome is used as the message.

E. Genera

i. Coronaviruses

a. Infectious bronchitis virus – Bronchitis

b. Human coronavirus – common cold

c. SARS coronavirus – SARS

ii. Toroviruses

a. Human torovirus – diarrhea

II. Negative sense Single-Stranded RNA viruses (ssRNA +)

α. Non-segmented

1. Rhabdoviridae

A. Name – rhabdos is Greek for “rod”. So named because of the rod-like structure

B. Structure – enveloped, bullet shaped, 5-10nm long & 3nm in diameter

C. Genome

i. negative sense single-stranded RNA (one segment)

ii. ~11 - 15 kbp

iii. genome contains neither a 5’ cap or a 3’ poly A tail

D. Message

i. contains both a 5’ cap and a 3’ poly A tail

E. Genera

i. Vesiculovirus

a. Vesicular stomatitis Indiana virus – vesicles on lips and tongue

b. Piry virus – febrile illness

ii. Lyssavirus

a. Rabies virus – rabies (malice then delirium then coma then death)

b. Mokola virus – like rabies

2. Filoviridae

A. Name – filo is derived from filament. So named because of the filamentous morphology

B. Structure – enveloped, filamentous morphology, 800-1000nm in length and 80nm in diameter.

C. Genome

i. negative sense single-stranded RNA (one segment)

ii. ~19 kbp

D. Genera

i. Marburg-like viruses

a. Marburg virus – severe hemorrhagic fever

ii. Ebola – like virus

a. Sudan Ebola virus – severe hemorrhagic fever

b. Zaire Ebola virus – severe hemorrhagic fever

3. Paramyxoviridae

A. Name – para meaning similar. myxo is derived from the Greek word muxa meaning mucus.

B. Structure – enveloped, capsid has helical symmetry(8-12nm in diameter), 150-350nm in diameter

C. Genome

i. negative sense single-stranded RNA (one segment)

ii. ~15 - 20 kbp

D. Genera

i. Respiroviruses

a. Human parainfluenza virus 1, 3 – respiratory disease

ii. Rubulaviruses

a. Mumps virus – mumps (parotitis, orchitis, meningitis)

b. Human parainfluenza virus 2, 4 – respiratory disease

iii. Morbilliviruses

a. Measles virus – measles (fever, rash, SSPE, immune suppression)

iv. Megamyxoviruses

a. Hendra virus - respiratory disease, encephalitis

b. Nipah virus - respiratory disease, encephalitis

β. Segmented

1. Orthomyxoviridae

A. Name – ortho meaning normal. is derived from the Greek word muxa meaning mucus.

B. Structure – enveloped, segmented capsid that has helical symmetry, 80-100nm in diameter

C. Genome

i. negative sense single-stranded RNA

ii. 8 segments

ii. totaling ~14 kbp

D. Genera

i. Influenzaviruses A

a. Influenza A virus – respiratory disease

ii. Influenzaviruses B

a. Influenza B virus – respiratory disease

iii. Influenzaviruses C

a. Influenza C virus – respiratory disease

iv. Thogoto-like virus

a. Thogoto virus

2. Bunyaviridae
A. Structure – enveloped, segmented capsid that has helical symmetry (200-3000nm long), 80-120nm in diameter

B. Genome

i. negative sense single-stranded RNA

ii. 3 segments

ii. totaling ~12 kbp

C. Genera

i. Bunyavirus - arboiviruses

a. La Crosse virus - encephalitis

ii. Nariovirus – arboiviruses

a. Crimean-Congo fever virus - hemorrhagic fever

iii. Phlebovirus – arboiviruses

a. Sandfly fever virus – nonfatal febrile illness

b. Rift valley fever virus - hemorrhagic fever

3. Arenaviridae

A. Name – arena is Greek for “sand”. So named because they often incorporate host ribosomes into the virion.

B. Structure – enveloped, segmented capsid that has helical symmetry, 100nm in diameter.

C. Genome

i. negative sense single-stranded RNA

ii. 2 segments

ii. totaling ~11 kbp

D. Genera

i. Old world arenaviruses

a. Lassa fever virus - hemorrhagic fever

ii. New world arenaviruses

a. Guanarito virus - hemorrhagic fever

b. Junin virus - hemorrhagic fever

c. Machapo virus - hemorrhagic fever

d. Sabia virus - hemorrhagic fever

III. Double stranded RNA viruses (dsRNA)

1. Reoviridae

A. Name – reoviridae is derived from respiratory enteric orphan viruses.

B. Structure – transiently enveloped (envelope is lost) and non-enveloped, icosahedral capsid, capsid can have up to 3 protein shells, 60 – 80nm

C. Genome

i. double-stranded RNA

ii. 10-12 linear segments totaling 16-27kb

iii. segments are in eqimolar quantities (one of each segment for each virus)

iv. can reassort gene segments

D. Genra

i. Orthroreoviruses

a. Mammalian reovirus types 1,2,3 – gastroenteritis, respiratory disease

ii. Orbiviruses

a. Changuinola virus – fever

b. Kemerovo virus (arboivirus) – fever, encephalitis

iii. Coltiviruses - arboiviruses

a. Colorado tick fever virus – fever, encephalitis

iv. Rotavirus

a. Group A rotavirus – infant diarrhea

b. Group B rotavirus – epidemic adult diarrhea

VI. Reverse transcriptase viruses

1. Retroviridae

A. Name – the prefix retro means “in the opposite direction”. So named because the viruses use a backwards flow of information (RNA to DNA).

B. Structure – enveloped, varying capsid symmetries (cone, rod, truncated cone), 80-100nm in diameter

C. Genome

i. positive sense single-stranded RNA

ii. 7-10 kbp

iii. diploid

iv. at least four genes: gag, pro, pol, env

v. genome has 5’ cap and 3’ polyA

D. Genera

i. Deltaretroviruses

a. Primate T-lymphotropic virus 1, 2 – T-cell lymphoma, neurological disorders.

ii. Lentiviruses

a. Human Immunodeficiency virus 1, 2– AIDS

2. Hepadnaviridae

A. Name – hepa refers to the liver tropism and dna refers to the DNA genome of the virus.

B. Structure – enveloped, icosahedral capsid, 40-48nm in diameter

C. Genome

i. Circular double stranded DNA

ii. 3.2 kbp

D. Genera

i. Orthohepadnaviruses

a. Hepatitis B Virus – hepatitis, hepatocellular carcinoma, cirrhosis

V. Double stranded DNA viruses

1. Poxviridae

A. Name – named after the pox lesions they cause

B. Structure – enveloped, dumbbell shaped nucleocapsid with flanking lateral bodies, overall brick shape, 350 x 270 nm.

C. Genome

i. linear double-stranded DNA

ii. 130-375 kbp

D. Message

i. cap-dependant

ii. poly A tail

E. Genera

i. Orthopoxviruses

a. Variola virus – smallpox

b. Monkeypox virus – smallpox-like

c. Vaccinia virus – localized lesions

ii. Parapoxviruses

a. Orf virus – localized lesions

b. Pseudocowpox virus – localized lesions

iii. Yatapoxviruses

a. Yaba monkry tumor virus – localized lesions

iv. Molluscipoxviruses

a. Molluscum contagiosum virus – nodular legions

2. Herpesviridae

A. Name - herpes is the Greek verb “to creep” referring to the legions the simplex viruses cause.

B. Structure – enveloped, icosahedral capsid, 100-300nm in diameter

C. Genome

i. linear double stranded DNA

ii. high GC content

iii. 120-230 kbp

D. Subfamilies/Genera

i. Alphaherpesviridae

a. Simplex viruses

- Herpes simplex virus 1 (HHV-1) – cold sores, ocular herpes

- Herpes simplex virus 1 (HHV-2) – genital ulcers

b. Varicelloviruses

- Varicella-Zoster virus (HHV-3) – chickenpox (varicella), shingles (zoster)

ii. Betaherpesviridae

a. Cytomegaloviruses

- Cytomegalovirus (HHV-5) - *during immunodeficiency: pneumonitis, retinitis, G.I. ulsers

b. Roseoloviruses

- Human herpesvirus 6 (HHV-6) – roseola infantum

- Human herpesvirus 7 (HHV-7) – similar to roseola infantum

iii. Gammaherpesviridae

a. Lymphocryptoviruses

- Epstien-Barr virus (HHV-4) – infectious mononucleosis, Hodgkin’s lymphoma, Burkitt’s lymphoma

b. Rhadinoviruses

- Kaposi’s sarcoma-associated virus (HHV-8) – Kaposi’s sarcoma, primary effusion lymphoma

3. Adnoviridae

A. Name – adeno is referring to the tropism of these viruses for the adenoids

B. Structure – non-enveloped, icosohedral, 70-90nm in diameter

C. Genome

i. linear double stranded DNA

ii. 36 kbp

D. Genera

i. Mastadenoviruses

a. Human adenovirus (>50 serotypes) – enteritis, pneumonia, upper respiratory disease

4. Polyomaviridae

A. Name – named after polyomas that they can cause.

B. Structure – non-enveloped, icosohedral, 40nm in diameter

C. Genome

i. circular double stranded DNA

ii. 5 kbp

D. Genera

i. Polyomaviruses

a. Simian virus 40 (doesn’t normally infect humans)

b. BK polyomavirus – childhood reparatory disease, progressive multifocal leukoencephalopathy

c. JC polyomavirus - childhood reparatory disease, progressivve multifocal leukoencephalopathy

5. Papillomaviridae

A. Name - named after papillomas or warts that they can cause.

B. Structure – non-enveloped, icosohedral, 55nm in diameter

C. Genome

i. circular double stranded DNA

ii. 6-8 kbp

D. Genera

i. Human papillomavirus 1-82 – genital warts, common warts, cervical carinoma