acellular microbes 1 Flashcards
- Obligate intracellular parasite (cannot reproduce outside host cell)
- Very small and simple in structure (ranges from 10nm-300nm)
- Infects not only humans and animals but also plants, fungi, protozoa, algae, and bacterial cells
- Observed using electron microscope
virus
complete, fully developed, infectious particles
VIRIONS
virions is composed of:
Nucleic Acid
Capsid
Envelopes
outer envelop composed of lipids and polysaccharide (some virus lack envelopes
Envelopes
genome of either DNA/RNA
Nucleic Acid
protein coat composed of many small protein units called capsomeres
Capsid
cause specific types of cancer like: lymphoma, carcinoma
oncovirus/Oncogenic Viruses
capsid plus the enclosed nucleic acid
nucleocapsid
Five specific properties that distinguishes virus from living things:
- Possess either DNA or RNA
- Unable to replicate without host cell
- Do not divide by binary fission, mitosis, meiosis
- Lack genes and enzymes for energy production
- Depend on host cell for protein and nucleic acid production
CLASSIFICATION OF VIRUSES
- Type of genetic material either DNA/RNA
- Number of capsomeres
- Shape of the capsid
- Size of capsid
- Presence/Absence of envelope
- Type of host it infects
- Type of disease it produces
- Immunologic/ antigenic property
- Target cell
Type of genetic material either DNA/RNA
a. double-standed DNA
b. single-stranded RNA
c. single-standed DNA
d. double-stranded RNA
Shape of the capsid
a. Polyhedral – many sides (20 sides)
b. Helical – coiled tubes
c. Bullet shape
d. Spherical shape
e. Complex combination
- Not labile/transient
- Replicate in Nucleus
- Viral DNA resembles host
DNA for transcription and
replication - Viral genome remains in
infected cell
DNA VIRUSES
determines the mechanism of transcription and replication
Genome structure
- Labile/transient
- Most replicate in Cytoplasm
- Prone to mutation
- Must encode an RNA dependent RNA polymerase
- Genome structure
RNA VIRUSES
spreads through fecal-oral route (contaminated water, untreated water from swimming pool, lakes)
– causes gastroenteritis
Astroviruses
highly contagious virus that causes mild to severe respiratory infection and oral disease in cats
Feline calcivirus
primarily causes enteric disease
calciviruses
- also called orthoreoviruses which causes upper respiratory infection, enteritis, fever, and febrile exanthema in childhood
– first discovered in stool of children
reoviruses
epidemic acute gastroenteritis (most common cause of diarrhea in adults)
Norwalk virus
has 5 general types:
Picornaviruses
Picornaviruses 5 general types:
1.Enteroviruses
2.Rhinoviruses
3.Hepatoviruses
4.Cardioviruses
5.Aphthoviruses