unit 5 Flashcards
Viruses
- require living host
- discovered by iwanowski
- do not respond to antibiotics
Are viruses sensitive to interferons
yes
Do viruses possess both DNA and RNA
No; only either one
Do viruses generate ATP like bacteria?
No
Do viruses have ribosomes, plasma membrane, go through binary fission?
No
Do viruses pass through bacteriologial filters
yes
Why can viruses not make their ATP/ protein synthesis
because they lack the enzymes to do, they rely on host
requirements for viruses
- contains DNA or RNA never both
- protein coat that surrounds nucleic acid ( can be envelope)
- has structures that allow it to transfer viral nucleic acid -> host
- uses host cell machinery to multiply
- has few to no enzymes of their own
Host range
determined by host cell attachment sites
- specific to host species
Mycophages
consist of plants, animals, fungi
Bacteriophages
consists of protozoa and bacteria
What microscope is needed to see viruses
electron (EM) microscope
What are bacteriophages
viruses that kill bacteria
What are viral structures for viruses?
- envelope
- capsid
- spikes
-nucleic acid
Outer coat (capsid)
-made of proteins
- capsomeres are the units
- protects nucleic acid of virus from enzymes
What is the effect of enzymes on the nucleic acid?
can degrade/ denature nucleic acids
Nucleic acid (innercore)
- bacteriophages
- Animal viruses = dsDNA ssDNA ssRNA dsRNA
Some viruses have what strucutres?
envelopes and spikes
Envelope
- made of proteins, lipids, carbohydrates
- surrounds capsid
What does a naked virus lack
lacks envelope
What kind of DNA or RNA do animals viruses have
can either be single or double stranded RNA or DNA
What kind of DNA do bacteria have
ONLY double stranded DNA
Spikes
- made of carbohydrate protein
- attachement to envelope
- helps virus attach to host
- sometimes used to ID viruses
Eveloped helical virus
has envelope/ nucleic acid is long rod that is flexible/ rigid
Naked helical virus
- lacks envelope
rabies virus and ebola virus are examples of what type of virus
- naked helical virus
naked polyhedral virus
- capsid has polyhedral shape
- lacks envelope
polio virus and adenovirus are examples of what type of virus
naked polyhedral virus
Complex virus
- has sheath , baseplate , pins, tail fibers
-attack bacteria
bacteriophages and poxy virus are examples of what type of virus
complex virus
Baseplate
used to lean against host cell
Pin
used to drill holes in host cell
Sheath
expands/ contracts on bacteria
tail fiber
attaches to bacteria
Where can bacteriophages grow
grow host bacteria in petri dish / inoculate with bacteriophage
What do you look for when growing bacteriophages
plaque formation
Culture
used to grow bacteriophage
what media is used to grow bacteriophage
solid agar
Ways animal viruses are grown
- embyronated eggs
- living animals
- tissue or cell culture
What is the preferred way to grow animal viruses
tissue or cell culture
electron microscope , serology methods , and molecular methods (nucleic acid synthesis) are used for what
identifying viruses
Viral antigens
rotavirus
viral antibodies
HIV/ rubella
what 2 cycles do bacteriophages go through
1) lytic cycle
2) lysogenic cycle
Lytic cycle
- always end with lysis and host cell death
-host cell will die / break apart
stages of lytic cycle
- attachment or reabsorption
- penetration (viral dna inserted into host cell)
- biosynthesis (eclipse period)
- maturation (virions)
-release (burst)
What are mature viruses called
virions
What happens in maturation stage of lytic cycle
mature viruses will asemble and form virions
what happens in the release stage of lytic cycle
lysis of host cell will occur
Lysogenic cycle
- when bacteria is lysed it is then integrated into bacterial chromosome
stages of lysogenic cycle
- attachment
-penetration - integration
Integration stage (become prophage) of lysogenic cycle
phage DNA becomes integrated into bacterial chromosome
the 4 possible outcomes of lysogenic cycle
- host cell can not be reinfected by the same phage but host cell be susceptible to other phages
- host cell may exhibit new properties
- back to lytic stage
-transduction
multiplication of animal viruses
- budding of an enveloped virus
- can only affect animal cell
what strucutre of an animal cell will create envelope
plasma or cell membrane
How does animal virus multiplication differ from versus bacteriophages?
- entire animal virus enters host (capsid/ nucleic acid)
- capsid needs to be stripped away (uncoating)
- DNA viruses replicate in nucleus/ RNA viruses replicate in cytoplasm
- Naked viruses
- enveloped viruses bud out (host cell membrane become envelope)
What is the effect that animal viruses have after an enveloped virus has infected and left the host cell?
CPE (cytopathic effects)
CPE
-visible effects that can damage or change the host cell
- it will leave behind something that will either harm/ or benefit you
Types of CPE’s
-inclusion bodies
-synctium cells
-change in host cell function
- interferon production
- chromosomal damage to host cell
- loss of contact inhibition resulting in unregulated cell growth
Inclusion bodies
- unassembled viral parts
- rabies virus produce negri bodies
Syncytium cells
-adjacent cells that fuse together to create larger cells
- forms a polykaryocyte (many nuclei)
- found with measles / mumps / colds
Interferon production
- antiviral protein
-part of immune system - created in small amounts
-produced by infected cells to protecting neighbouring uninfected cells from being infected (host defense) - inhibits protein synthesis of virus
Single stranded DNA viruses
Parvovirus (small virus)
Parvovirus
- gastroenteritis; fetal death
- co-infection with adenovirus
- cause rapid dehydration in cats/dogs
-causes 5th disease
Double stranded DNA viruses
- Papoviruses
- adenovirus
- Herpes viruses (herpes simplex , varicella zoster , cytomegalovirus, epstein barr virus
- Poxy virus
Papoviruses
- Papilloma (warts) , polyoma (tumors) , HPV
- causes common warts, plantar warts, genital warts
- transmission = direct contact / formites
-oncogenic viruses = cervical/oral/anal cancer
Treatment for papoviruses
cryosurgery / laser / chemicals
Gardasil / cervarix
Vaccine for genital warts (papoviruses)
Adenovirus
- respiratory infection
- various types
- affects children / infants
- causes gastrocenteritis / conjuctivitis (pink eye)
-oncogenic virus
Varicella zoster VZV (Herpes virus)
- varicella= chickenpox (effects children /infants)
- shingles (Zoster) = affects adults
- latent virus
-vaccine available for both
-opportunistic virus
Cytomegalovirus (Herpes virus)
- naturally acquired: RT
-opportunistic virus
-dangerous to pregnant woman - part of normal flora
Epstein Barr virus (EBV) (Herpes virus)
- viral infection of lymphoid/ glandular tissue
- caused by plasmodium
- causes infectious mononucleosis / cancer of lymph system
Poxy viruses- smallpox (Herpes virus)
- RT infection
- fluid filled vesicles (skin lesions)
- transmission = RT
-first vaccine = edward jenner
-concerned with bioterrorism today
Single stranded RNA virus
-Picornaviruses
-enteroviruses
- Toga viruses
-Orthomyoxovirus
- paramyxovirus
-Coronavirus
-Rhabdovirus
-Filovirus
2 types of picornaviruses (single stranded RNA)
- rhinovirus
- enterovirus
rhinovirus (single stranded RNA virus)
- 50% of all colds
-symptoms = sneezing, nasal secretions , congestion,
-complications = sinus infectios
Treatment for rhinovirus
treat symptoms
Transmission for rhinovirus
RT/ hand -> hand
different types of enteroviruses
-polio virus
- coxsackie
- hepatitis A
Poliovirus (enteroviruses)
-transmission = fecal/oral
- invades CNS to cause paralysis
Vaccines for polio virus
- Dr. Salk = injected
- Sabin- attuenuated = oral
Advantages/ disadvantages of injected polio vaccine
- 100% safe
- kills virus with heat /chemicals
-Disadvantage = not immunogenic/ antigenic
Advantages / disadvantages of oral polio vaccine
- easy to consume
- disadvantage = can still have polio virus in fecal matter (virus can return back due to only weakening virus not killing)
Coxsackie virus (enteroviruses)
- hand-foot-mouth disease
-Mycarditis in infants, diarrhea
-aseptic meningitis
-transmission = animal -> animal contact
Diagnostics for coxsackie virus
- checking csf
- blood culture
-gram staining
Hepatitis A (enterovirus)
- infectious hepatitis
- transmission = fecal /oral and food handlers
- carriers are rare
-food virus
Treatment for Hepatitis A
- Gamma/ immunoglobulin (antibodies) given if exposed; limited protection
The 2 types of togavirus (single stranded RNA)
-Arbovirus
-Flavivirus
Arbovirus types
- encephalitis
-rubivirus (rubella)
Encephalitis (type of arbovirus)
- carried by mosquitoes / ticks
- West nile virus
- has arthropod vector
Rubivirus also known as rubella ( type of arbovirus)
-Rubella or german measles
- often undetected because of small size
- given in 2 doses
- milder than regular measles
What is the vaccine for rubivirus (rubella /german measles)
MMR vaccine (measles, mumps, rubella)
The types of flavivirus
- Yellow fever
-Dengue fever - hepatitis C
Yellow fever (type of flavivirus)
- mosquitoe = vector
- endemic to tropical areas
-causes jaundice
Dengue fever (flavivirus)
- endemic in carribbean / tropical areas
- milder than yellow fever
- mosquitoe = vector
Hepatitis C ( flavivirus)
-transmission = blood -> blood pare-central
-no vaccines
- silent epidemic
- incubation = 20 years
= leading reason for liver transplants (is a liver disease)
the different type of Orthmyxovirus - myxo- mucus (type of picornavirus)
-influenza (flu)
Influenza
- symptoms = chill/fever
- can cause viral pneumonia
-prevention = wash hands / hand sanitizer
-transmission = respiratory secretions /hand -> hand - treatment = treat symptoms
-can travel to organs/ infect them
2 types of vaccines for influenza
- injected (unactivated)
-nasal spray (attenuated)
H5N1 strain of influenza (avian)
-chicken -> chicken transmission
-chicken -> human transmission
2 types of spikes that are part of influenza virus
- HA spike
-Na spike
Ha (hemagluttin) spike
- allows virus to recognize and attach to host cell
-500 Ha spikes/virus
Na (neuraminidase) spike
- helps virus exit infected cell
- then goes to neighbouring cell
-100 Na spikes/virus
What did the H1N1 swine flu cause
influenza
Paramyxovirus
- parainfluenza (cold)
- respiratory syncytial virus
The different types of paramyxoviruses
- parainfluenza (cold)
-respiratory syncytial virus - measles
-mumps
Parainfluenza / respiratory syncytial virus
- most common cause of acute respiratory diseases in infants/young children
-epidemics during winter /early spring
Measles (rubeoula) type of paramyxovirus
- upper RT infection
- extremely contagious
- transmission = RT
- symptoms = sensitivity to light , koplick’s spots , rash, fever, sore throat
What is the vaccine for Measles
- MMR vaccine in 2 doses
Mumps (type of paramyxovirus)
- inflammation of parotid glands
- transmission = RT secretion / saliva
- sterility is rare
What is the vaccination for mumps
- MMR vaccine
types of Coronovirus
- colds
-pneumonia - are RT infections
Rhabdovirus
- rabies
- transmisson = bite of an infected animal
- animal reservoirs = bats, dogs, racoons , cats , foxes
-found in saliva of animals
-causes inflammation of brain
What is the vaccination for rhabdovirus (rabies)
- vaccinate animals
- immunoglobulins
types of Filovirus
- ebola
-marburg virus
Ebola / marburg virus ( types of filoviruses)
- are hemmorhagic viruses ( disrupts blood-clotting factors)
- animal reservoir = fruit bats
- spread by contact with the blood/ body fluids
- no transmission during incubation period
Double stranded RNA viruses
- rotavirus
Rotavirus (type of double stranded RNA virus)
- adults build antibodies against rotavirus
- death in children due to dehydration
- infantile gastroenteritis
-symptoms = low grade fever / diarrhea and vomitting
2, 4, 6 MOA
vaccination for Rotavirus
Reverse transcript viruses
- RNA -> DNA
Types of reverse transcript viruses
-retrovirus
- Hepadnavirus
Retrovirus (type of reverse transcript virus)
- AIDS (accquired immunodeficency syndrome)
- HIV or HTLV III
-decreased helper T cells
-attaches to CD4 receptors
-end stage of aids - can cause skin cancer (Kaposis sarcoma)
- STD , blood , blood products , congenital
Hepadnavirus (type of reverse transcript virus)
- oncogenic
- hep B or HBV
- found in blood / saliva / semen (std)
- interferon used for chronic cases
-vaccine available
-test for Hep B surface antigen
Classification of animal viruses
- dermatotrophic
- pneumotropic
-neurotrophic - viscerotrophic
Dermatotrophic
- causes skin infections
-skin viruses
small pox , measles , mums , herpes , chickenpox are examples of what
dermatotrophic viruses
Flu , colds , RSV are examples of what
pneumotrophic viruses
Rabies, polio , encephalitis are examples of what
- neurotrophic viruses
Mumps, Hepatitis viruses are examples of what
viscerotrophic viruses (affect organs)
Prion
- protein coat only with no nucleic acids
-only proteins that can replicate - difficult to eliminate prions as boiling / autoclaving/ radiation not reliable
- puts holes in brain cells
-Spongiform encephalopathy (effects neurological involvement)
Use of strong NaOH and 134 degrees C
only way to eliminate prions
- sheep scrapie
- chronic wasting disease- deer / elk
- mad cow disease (BSE - Bovine spongiform encephalopathy)
-Creutzfeld-Jakob disease
diseases caused by prions
Kuru New Guinea
- rutuilistic canabilism
CJD (Creutzfeldt-Jakob disease)
- cognitive degeneration
- can be caused by alzheimers
- symtpoms = presenile dementia
-affects nervous system
Oncogenes
- activated by radiation , chemicals, viruses
- oncogenic viruses able to make tumors
Transformed cells
- loose contact inhibition
- less round than normal cells
- fragment /unusal number of chromosomes ( chromosomal abnormalities)
