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
transmitted via fecal route
Enteroviruses
- attacks lower motor neurons of spinal cord
– flaccid, asymmetrical paralysis
poliomyelitis
most common cause of common cold; causes URTIs
Rhinoviruses
infects vertebrates and causes myocarditis
Cardioviruses
Hepa A
Hepatoviruses
spread through fecal-oral route. Causes nausea, headache, cramping, fever, diarrhea
Rotaviruses
NONENVELOPED RNA VIRUS
Astroviruses
Calciviruses
Reoviruses
picornaviruses
Rotaviruses
responsible for foot-and-mouth disease
Aphthoviruses
positive-stranded RNA virus that causes encephalitis, arthritis, fever and rash
togaviruses
ENVELOPED RNA VIRUS
Togaviruses
Flaviviruses
Coronaviruses
Rhabdoviruses
Paramyxoviruses
Arenaviruses
Bunyaviruses
Orthomyxoviruses
Lentiviruses
Oncoviruses
mosquito transmitted human pathogen
Chikungunya virus
anthropod-borne virus causing life threatening disease symptoms like encephalitis and hemorrhagic fever
Flaviviruses
bullet-shaped virus with a spiked envelope
Rhabdoviruses
possesses distinctive arrangements of spikes on the viral surface (Crown-like)
coronaviruses
Flaviviruses includes:
a. West Nile virus
b. dengue virus
c. yellow fever virus
d. Japanese encephalitis virus
e. Hepa C
first infect the ciliated epithelial cell of the nose and throat
Paramyxoviruses
what are H1N, H2N2, H3N2?
Spanish Flu, Asian Flu, Hong Kong Flu
genus of retroviruses that cause chronic and deadly diseases characterized by long incubation periods in humans and other mammalian species
Lentiviruses
pleomorphic enveloped particles that contain two RNA segment of virus origin
Arenaviruses
arthropod-borne and rodent-borne viruses causes fever, hemorrhagic fever, renal failure, encephalitis, meningitis, blindness
Bunyaviruses
causes influenza, acute respiratory disease with prominent systemic symptoms
Orthomyxoviruses
virus that causes cancer
Oncoviruses
HPV (warts)
Papillomavirus
- tumor
– natural hosts are mammals and birds
Polyomavirinae
common virus people get in childhood; occurs
with immune compromised individuals
BK VIRUS/ Human polyomavirus 1
disease of the white matter of the brain. Can be dangerous to individuals with weak immune system
JC VIRUS/ Human polyomavirus 2
simplest and smallest single-stranded DNA virus
Parvoviridae
- causes “Fifth disease/Erythema infectiosum”
– also called “slapped cheek disease” because of rash
– common and very contagious (spreads in droplets when infected person
PARVOVIRUS B19
- most common cause of colds
– causes respiratory diseases
– conjunctivitis (pink eye)
Adenoviridae
nonenveloped DNA viruses:
Polyomavirus
Papillomavirus
Parvovirus
Adenoviruses
very large, complex, brick-shaped virus
Poxviridae
hepatitis B virus that infects hepatocytes and may cause liver injury
Hepadnaviridae
first disease to be declared eradicated form earth(1980)
Variola virus: smallpox
originally used as vaccine against smallpox.
Vaccinia virus
