Prions• Infectious proteins

• Inherited and transmissible by ingestion, transplant, and surgical

instruments

• Spongiform encephalopathies: Sheep scrapie, Creutzfeldt-Jakob

disease, Gerstmann-Sträussler-Scheinker syndrome, fatal familial

insomnia, mad cow disease

• PrPC: Normal cellular prion protein, on cell surface

• PrPSc: Scrapie protein; accumulates in brain cells forming plaques

Prions

Figure 13.22

• Plant viruses: Enter through wounds or via insects.

• Viroids: Infectious RNA; e.g., potato spindle tuber disease.

Figure 13.23

Some Plant Viruses

Table 13.6

• Single-stranded DNA, nonenveloped viruses– Parvoviridae

• Human parvovirus• Fifth disease• Anemia in

immunocompromised patients

Table 13.2 (1 of 20)

Virus Families

Single-Stranded RNA, + Strand, Nonenveloped

• Enterovirus– Enteroviruses include

poliovirus and coxsackievirus.

• Rhinovirus• Hepatitis A virus

Table 13.2 (7 of 20)

Double-Stranded DNA, Nonenveloped Viruses

• Mastadenovirus– Respiratory infections

in humans– Tumors in animals

Table 13.2 (2 of 20)

Double-Stranded DNA, Nonenveloped Viruses

• Papillomavirus (human wart virus)

• Polyomavirus– Cause tumors; some

cause cancer

Table 13.2 (3 of 20)

Double-Stranded DNA, Enveloped Viruses

• Orthopoxvirus (vaccinia and smallpox viruses)

• Molluscipoxvirus– Smallpox– Molluscum

contagiosum– Cowpox

Table 13.2 (4 of 20)

Double-Stranded DNA, Enveloped Viruses

• Simplexvirus (HHV1 and HHV 2)• Varicellavirus (HHV 3)• Lymphocryptovirus (HHV 4)• Cytomegalovirus (HHV 5)• Roseolovirus (HHV 6)• HHV 7• Kaposi's sarcoma (HHV 8)

– Some herpesviruses can remain latent in host cells.

Table 13.2 (5 of 20)

Double-Stranded DNA, Enveloped Viruses

• Hepadnavirus (Hepatitis B virus)– Use reverse

transcriptase to produce DNA from mRNA.

Table 13.2 (6 of 20)

Single-Stranded RNA, + Strand, Nonenveloped

• Hepatitis E virus• Norovirus causes

gastroenteritis.

Table 13.2 (8 of 20)

Single-Stranded RNA, + Strand, Enveloped

• Alphavirus– Alphaviruses are

transmitted by arthropods; include EEE, WEE.

• Rubivirus (rubella virus)

Table 13.2 (9 of 20)

Single-Stranded RNA, + Strand, Enveloped

• Arboviruses can replicate in arthropods; include yellow fever, dengue, SLE, and West Nile viruses

• Hepatitis C virus

Table 13.2 (10 of 20)

Single-Stranded RNA, + Strand, Enveloped

• Coronavirus– Upper respiratory

infections– SARS

Table 13.2 (11 of 20)

Single-Stranded RNA, – Strand, One RNA Strand

• Vesiculovirus • Lyssavirus (rabies

virus)• Cause numerous

animal diseases

Table 13.2 (12 of 20)

Single-Stranded RNA, – Strand, One RNA Strand

• Filovirus– Enveloped, helical

viruses– Ebola and Marburg

viruses

Table 13.2 (13 of 20)

Single-Stranded RNA, – Strand, One RNA Strand

• Paramyxovirus• Morbillivirus• Paramyxovirus

– Parainfluenza– Mumps– Newcastle disease

Table 13.2 (14 of 20)

Single-Stranded RNA, – Strand, One RNA Strand

• Hepatitis D virus– Depends on

coinfection with Hepadnavirus

Table 13.2 (15 of 20)

Single-Stranded RNA, – Strand, Multiple RNA Strands

• Influenzavirus (Influenza viruses A and B)

• Influenza C virus– Envelope spikes can

agglutinate RBCs.

Table 13.2 (16 of 20)

Crossing the Species Barrier

UN 13.3

Single-Stranded RNA, – Strand, Multiple RNA Strands

• Bunyavirus (CE virus)• Hantavirus

Table 13.2 (17 of 20)

Single-Stranded RNA, – Strand, Multiple RNA Strands

• Arenavirus– Helical capsids contain

RNA-containing granules

– Lymphocytic choriomeningitis

– VEE and Lassa Fever

Table 13.2 (18 of 20)

Single-Stranded RNA, Two RNA Strands, Produce DNA

• Lentivirus (HIV)• Oncogenic viruses

– Use reverse transcriptase to produce DNA from viral genome.

– Includes all RNA tumor viruses

Table 13.2 (19 of 20)

Double-Stranded RNA, Nonenveloped

• Reovirus (Respiratory Enteric Orphan)

• Rotavirus– Mild respiratory

infections and gastroenteritis

• Colorado tick fever

Table 13.2 (20 of 20)