Final Exam Flashcards
Taxonomy of Viruses
What do these suffixes refer to?
- virales
- viridae
- virinae
- virus
- virales: Orders
- viridae: Family
- virinae: subfamily
- virus: genera
Initial classification of viruses is made by ______ and how many of each are of clinical importance?
nucleic acid composition
RNA-14 families
DNA-6 families
Types of viral diseases
- Respiratory
- Enteric
- Exanthematous (skin eruptions)
- hepatitis
- persistent (latent)
Viruses are what type of pathogen?
obligate intracellular pathogen
cannot replicate outside of a host cell
What is tropism?
Viruses are host specific, meaning they have a limited number of hosts they can infect and survive in.
When are you considered contagious with a viral infection?
Varies
norovirus-from the time you display symptoms up yo 3 days after recovery
common cold-2-3 days after symptoms occur and lasts for a week
What is:
Antigenic Shift?
Antigenic Drift?
Antigenic Shift-infrequent major changes in the genetic structure of a virus (possibly incorporating host DNA into its viral genetic structure) creating a completely new virus
Antigenic Drift-minor changes in the genetic structure that occur during replication and this can occur all the time. The resulting virus is similar to the original with similar antigenic properties ( the immune system may still recognize it). Immunity can be lost over time due to the accumulation of the changes.
need for seasonal influenza vaccine
What is a virion?
It is measured in….
virus particle
nanometers
Viruses use ____ to replicate because they cannot _______.
- host cell machinery
- self replicate
Structural components of a virion
Genetic material (DNA or RNA) capsid (made of capsomeres)
Possible:
envelope
glycoprotein spikes
What are capsomeres?
repeating structural subunits that make up the capsid
What is a capsid?
Protein coat that encloses the virus’s genetic material.
genome + capsid=nucleocapsid
What is a virion envelope and what is it prone to?
A lipid membrane that surrounds the capsid of certain viruses.
Prone to drying, thus transmission is via direct contact (prevent exposure to environment)
What are vision glycoprotein spikes?
attached projections on the surface of a virion that aid in stabilization and may have some enzymatic activities.
These projections can change, which also impairs a need for seasonal influenza vaccines.
Modes of viral transmission:
Which one is considered the most common route?
- direct contact
- injection with contaminated fluids or blood
- organ transplantation
- fecal-oral
- respiratory (inhalation is the most common route)
Viral disease progression
1-acquisition 2-attachment 3-penetration 4-uncoating 5-replication 6-macromolecular synthesis 7-assembly 8-release
Viral disease progression
Acquisition
Entry into the body
viruses can enter the body via inhalation, but cause infection elsewhere in the body
Spreads via the blood or lymphatics
Symptoms of disease-due to tissue damage and host immune response
Viral disease progression
Attachment
Recognition/binding to host cell receptors
Tropism-infect only certain tissues due to recognition of limited numbers of host cells
Viral disease progression
Penetration
Process of entering host cell
Mechanism(s)
- fusion of viral envelope with host cell membrane
- penetrating host cell membrane with tail
Viral disease progression
Uncoating
releasing viral genetic material into the host cell
Viral disease progression
Macromolecular synthesis
production of nucleic acids/protein polymers
mRNA encodes early and late proteins
Early proteins: nonstructural, usually enzymes
Late proteins: structural
Viral disease progression
Assembly
arrangement of structures
Virion becomes intact and is ready for release
Viral disease progression
Release
Via host cell lysis OR budding with cytoplasmic membranes
Influenza virus-hemadsorption
Common cells used for detection of viruses
These are examined periodically to look for:
human diploid fibroblasts, human epidermoid, primary monkey kidney
examined to observe cytopathic effects
Histologic detection of viruses
via H&E or special stains and identifying intracellular/intranuclear inclusions (cytopathological effects)
Examples: multinucleate cells, inclusion bodies
“owl eye inclusions” in lung pneumocyte-CMV
Viral detection methods
Viral cell cultures histology serology Ag detection via rapid tests Electron microscopy MALDI-TOF
Type of swab to use when collecting viral specimens and why?
Universal transport swabs by BD (transport media contains proteins to stabilize the viruses and antimicrobials to prevent growth of bacteria)
Calcium alginate swabs are NOT acceptable due to interface with PCR and fluorescent antibody testing
Viral cell cultures are inoculated with _____ to ______ uL of specimen
Viral cell cultures are inoculated with 200 to 400 uL of specimen
Processing viral specimens
Varies depending on the source, but can include:
setting up a cell culture
Direct detection
A viral specimen should be processed ______ upon receipt in lab.
Immediately
Viral specimen sources
bronchial washes rectal swabs/stool vesicular lesions of skin mucous membranes CSF blood bone marrow tisse cervical swabs
The amount of viral infections/diseases has increased with the advent of:
improved medical technologies (organ transplantation, cancer care….both lead to immunosuppression
How does hemadsorption work to detect influenza in cell line cultures?
The virus manufactures glycoprotein hemagglutinins that get inserted into the host cell membrane, then later get incorporated into the virus during budding
In cell culture, adding RBCs will cause the RBC to adsorb to surface membrane of virally infected cells only and can be visualize microscopically.
Viral Pathogenesis:
Possible outcomes of viral infections
Transient illness chronic infection laten infections cancer Death of host
Bunyaviruses
Genetic material:
Envelope?
Vector:
Important viruses within this family:
Genetic material: 3 single strands of RNA
(**tripartite genome**)
Envelope? yes
Vector: mosquito
Important viruses within this family:
Arbovirus and HentavirusesHentaviruses are _____, but are not ________.
Transmission?
Bunyaviruses, but are not Arboviruses
Transmission via inhalation of rodent excrement
Bunyaviruses infection/disease
Arboviruses
California encephalitis, (self-limiting)
LaCrosse viruses (asymptomatic to neuroinvasive)
Real-time PCR measures….
the amplified products in real-time rather than at the end of a series of cycles
Most common viral agent causes gastroenteritis in the U.S.
norovirus
Norovirus more commonly infects _____ whereas sapovirus more commonly infects ______.
Norovirus more commonly infects all ages whereas sapovirus more commonly infects infants and children
Calicivirus general: Norovirus
Linked to outbreaks of gastroenteritis:
Transmission:
Diagnostic testing:
Linked to outbreaks of gastroenteritis: on cruise ships, in nursing homes, schools
Transmission: contaminated water, person-to-person, airborne droplets of vomitus
Diagnostic testing: real-time PCR
Caliciviruses
Genetic material:
Major Genera:
Infections:
Genetic material: RNA
Major Genera: norovirus and savories
Infections: gastroenteritis
The term “arbo” virus refers to……
What families of viruses are part of this group?
arthropod borne viruses
(transmission via arthropod vectors)
Bunyaviridae, Togaviridae, Flaviviridae
Arenaviruses
1-Enveloped? 2-Genetic material: 3-Glycoprotein spikes: 4-Transmission: 5-Infections:
1-yes 2-RNA 3-T-shaped 4-inhalation of aerosols from rodent/bat excretement 5-Lassa Fever
**Can cause fever, headache, possibly meningitis and hemorrhagic fever
80% are asymptomatic
Targets for antiviral drugs
- Attachment (neutralizing Abs: HIV)
- Penetration and Uncoating (Amantadine, rimantadine: Influenza A)
- Transcription
- Protein synthesis
- DNA replication
Adenoviruses
1-Envelope?
2-Genetic material:
3-Infections:
4-Transmission:
1-No
2-Genetic material: dsDNA
3-resp. infections in children, gastroenteritis, keratoconjuntivitis
4-via aerosolized droplets or could be airborne
Coronaviruses
1-Transmission:
2-Genetic material:
3-Envelope?
1-via respiratory secretions and aerosals
2-RNA
3-yes
4-commmon cold and SARS
Genera of coronaviruses that causes the common cold
coronavirus
Hentavirus Pulmonary Syndrome
Symptoms start as _____ and then progress to _______.
1-common name:
2-Primary Host:
Transmission:
- fever, headaches
- hemorrhagic fever, kidney disease, and acute respiratory failure.
1-Sin Nobre Virus (SNV)
2-Deer mouse
3-via inhalation of excrements
Filovirus
1-Genetic material: 2-Envelope? 3-Structure: 4-Most pathogenic of: 5-Important viruses:
1-RNA 2-yes 3-long, threadlike 4-hemorrhagic fever viruses 5-Ebola and Marburg viruses
Filoviruses: Marburg Virus
1-first individuals infected were exposed to:
Reservoir:
2-Initial symptoms include ____ and then progress to ______.
3-Death rate of initial outbreak in 1967:
1-African green monkeys
reservoir=fruit bats
2-Initial symptoms include fever,chills, headache, myalgia and then progress to rash on the trunk of the body, nausea, vomiting, chest pain, jaundice, massive internal hemorrhaging, and multi-organ dysfunction.
3-25%
Filoviruses: Ebola
Treatments
Supportive treatments:
IV to balance electrolytes
Oxygen therapy
Treat other infections if/when they occur
Experimental vaccines are under development
Filoviruses: Ebola
1-Reservoir:
2-Transmission:
1-Reservoir-unknown
2-Transmission-via direct contact through broken skin or mucous membranes with body fluids of infected individuals
NOT spread through the air or food
Filoviruses: Ebola
1-symptoms:
2-Diagnosis
1-fever, headache, muscle pain, weakness, fatigue, diarrhea, vomiting, abdominal pain, bleeding from the eyes and/ or bruising
survivors can develop antibodies that last for 10 years
2-Blood tests to detect viral antigens
Flaviviruses
1-Vector/Transmission:
2-Important viruses/infections:
1-Mosquitos
2-Zika, West Nile, Yellow Fever
Flaviviruses: Zika Virus 1-Vector: 2-Reservoir: 3-Transmission: 4-Symptoms:
1-Aedes mosquito
2-unknown
3-mosquito bite, sexual contact, crossing the placenta
4-rash,fever, muscle/joint pain, conjunctivitis, usually mild
Paramyxoviruses
1-Enveloped?
2-Genetic Material:
3-Infections:
1-yes
2-RNA
3-Measles, Mumps, Rubella, RSV
Paramyxoviruses: Respiratory Syncytial Virus (RSV)
Causes ______ in young children and is the most significant acute lower respiratory tract infection in _____.
bronchiolitis
children under 5
Orthomyxoviruses
1-Genetic material: 2-Genera: 3-Transmission: 4-Symptoms: 5-Type of vaccine:
1-RNA 2-Influenza A,B, and C 3-via inhalation of aerosolized particles 4-fever, malaise, headache, body aches 5-killed vaccine (inactivated)
Picornaviruses
1-enveloped?
2-Genetic Material:
3-Important:
1-no
2-RNA
3-rhinovirus,enteroviruses (polioviruses, Coxsackie virus, hepatitis A)
Viral agents that cause the common cold:
Coronavirus and rhinovirus
Papillomaviruses
1-Genetic material 2-Enveloped? 3-Infects: 4-Infections: 5-Transmission:
1-dsDNA
2-no
3-skin and mucous membranes (genital,oral, conjunctival)
4-warts on the skin, Condyloma acuminate (genital warts), Cervical Intraepithelial Neoplasia (CIN) and cancer
5) sexually or via fomites
Papillomaviruses:
Types of causes:
1-Warts of the skin:
2-Genital Warts:
3-CIN and Cancer:
1-HPV-1 through HPV-4 (skin warts)
2-HPV-6 through 11 (genital warts)
3-HPV-16 and 18 (Cancer)
Causative agents of infectious mononucleosis
Epstein-Barr virus
and
Cytomagalovirus
Herpesviridae Types.... 1 & 2: 3: 4: 5: 6 & 7: 8:
1 & 2: Herpes simplex virus (HSV) 3: Varicella-zoster virus 4: Epstein-Barr virus 5: Cytomegalovirus 6 & 7: both can cause roseola 8: Kaposi-sarcoma-related virus
What is roseola?
Caused by Herpesviruses 6 & 7
red eyes, runny nose, sore throat, and generalized rose colored skin rash that resolves within 48 hours
Life long latent infection of T-cells
HSV 1 & 2
1-cause:
2-Transmission:
1-oral or genital lesions
2-Transmission:
HSV-1 via kissing or other saliva contaminated items.
HSV-2 via sexual contact
*cause benign disease, but can be fatal if it makes its way to the brain (encephalitis) in neonates or immunocompromised
Cytomegalovirus
1-Harbored in the cervix of some: 2-Can cause: 3-Transmission: 4-Symptoms: 5-Histological findings:
1-pregnant women 2-infectious mono 3-sexual contact 4-asymptomatic 5- "owl eye inclusions"-basophilic nuclear inclusion with a clear halo, cell greatly enlarged
Most common dural cause for congenital defects.
….Causes microcephaly, intracerebral calcification, hepatosplenomegaly, and rash in neonates
Cytomegalovirus
Varicella-Zoster Virus
1-Causes:
2-Disease progression:
1-Chicken Pox that can lead to Shingles
2-After initial chicken pox, the virus remains dormant in sensory neurons and can reemerge as shingles
Shingles?
-vesicular lesions similar to chicken pox
Postherpetic neuralgia-chronic pain syndrome that can persist for months to years following shingles due to nerve destruction
Hepatitis Viruses
All target the liver:
A-RNA (Picornaviridae) B-DNA (Hepadnaviridae) C-RNA (Flaviviridae) D-requires confection with HBV E-RNA (Hepeviridae)
Epstein-Barr Virus
1-Causes: 2-Transmission: 3-Targets: 4-Associated with: 5-In AIDS patients, causes:
1-cause: infectious mono
2-Transmission: via saliva
3-Targets: B-lymphocytes
4-Associated with: lymphoma and nasopharyngeal carcinoma
5-In AIDS patients, causes: hairy oral leukoplakia
Transmission of Hep C virus
Parenteral: IV drug abuse, needlesticks
Sexual contact (not as effective as blood for transmission)
HCV
1-Pathigenesis:
2-Symptoms:
3-Diagnosis:
4-Treatment:
1-hallmarks of chronic inflammation: inflammatory cells, tissue death, healing through scar formation
2-asymptomatic at first….fever, fatigue, nausea, muscle/joint pain, jaundice (but can remain anicteric)
3-blood tests for antibodies or molecular methods to check genotype of HCV
4-Oral antiviral drugs (daclatasvir and sofosbuvir)….can become “clinically cured”
Cirrhosis
1-Etiology:
2-Pathogenesis:
3-Morphology:
4-Treatment:
1-alcohol, cryptogenic, hepatitis viruses B,C,D, and hereditary metabolic diseases
2-stellate cells secrete type I and type III collagen as a result of various cytokines secreted from leukocytes due to inflammatory response. The microvasculature is altered and hepatic cells proliferate in clusters 9 nodules.
3-nodules on the liver separated by fibrous septae
4-try and treat the source, hypertension medications, liver transplant
Rhabdoviruses
1-infect:
2-Example
3-Diagnosis
1-plants, animals, fish, and mammals
2-Rabies
3-nuchal skin biopsy and immunofluorescent test
Retroviridae contain ____ that goes against the central dogma to _______.
reverse transcriptase
convert RNA to DNA
How many individuals are unaware they are infected with HIV?
1 in 7
1-Retroviridae:
2-Routes of transmission:
3-not transmitted via:
1-HIV
2-blood transfusions, needle sticks, intercourse, intrauterine, breast milk
3-kissing, coughing, food, utensils, public bathrooms, swimming pools
Retroviridae:
-Disease course
-First few weeks, may exhibit flu-like symptoms, but then remain asymptomatic for years while still being contagious. If no antiviral treatment is used it may progress to AIDS
Retroviridae:
-Disease process
Target T-helper cells.
(GP-120 binds CD4 to enter the cell)
As the virus replicates, infects, and lyses cells, T-helper cells decrease in numbers, which affects both antibody and cell-mediated immune responses
HIV-1 is the most common cause
HIV-2 is less pathogenic
After release from the cells, antibodies and cytotoxic t-cells can help eliminate some of the viruses that are not intracellular yet
T-helper cells release cytokines that…..
- Activate macrophage to kill ingested antigens
- Activate the proliferation and differentiation of B and T lymphocytes
- Chemotaxis-recruits neutrophils and macrophage to the site of infection
Mechanisms by which HIV can escape elimination via the immune response:
- Rapid genetic mutations
- CD4 T-helper cells are rendered dysfunctional due to the viral infection
- Memory cells are also impaired by the viral infection
HIV is screened via _____ and confirmed by _______.
HIV is screened via enzyme immunoassays (EIAs) and confirmed by western blot
It is quicker to detect antigens than it is to detect antibodies
Most significant diseases in AIDS patients
Kaposi sarcoma-vascular tumor
Pneumocystis jerovecii pneumonia lymphomas
Most common parasitic infections in Central Wisconsin
-Giardia lamblia and Cryptosporidium
Risk factors for parasitic infections
poor hygiene
poor sanitation (water/sewage)
use of human feces as fertilizer
world travel/trade agreements
General types of parasites:
1-Endoparasites:
2-Ectoparasites:
3-Obligate parasites:
4-Facultative:
1-live inside host
2-live outside a host
3-must spend all or part of their lifecycle in a host
4-typically free living, but if they get into a host they can become parasitic
Types of Hosts
1-definitive:
2-intermediate:
1-one in which the parasite reaches productive maturity-sexual reproduction
2-one in which the parasite passes through its larval stage-asexual reproduction
Parasite methods of infection?
- penetration/boring
- ingestion of cysts,eggs, or larvae
- bite of a vector
Protozoa classes…
1-Lobosea:
2-Zoomastigophorea:
3-Kinetofragminophorea:
4-Sporozoea:
1-move via pseudopodia
2-move via flagella
3-move via cilia
4-adult stage is nonmotile
Amoeba organisms
- Entamoeba spp
- Iodamoeba butcshlii
- Endolimax nana
Free living amoeba organisms
- Naegleria fowleri
- Acanthamoeba spp
Ciliate organisms
Balantidium coli
Flagellate organisms
- Giardia lamblia
- Chilomastix mesnili
- Dientamoeba fragilis
- Trichomonas spp
Malaria organisms
plasmodium spp
sporozoa organisms
- Toxoplasma gondii
- Cryptosporidium parvum
- Babesia microtti
- Isospora belli
- Cyclospora cayetanensis
- Sarcocystis hominis
Hemoflagellate organisms
- Leishmania spp
- Trypanosoma spp.
Trophozoite characteristics
- Motile and Feeding
- found in definitive host Reproducing
- Unicellular with dark, irregular thickened ring of chamoatin around nuclear periphery and a large eccentric nucleus containing large karyosome
Cyst characteristics
- Non-motile and Non-feeding
- Infective
- Dorment, protective stage found in environment
- Can boomlet-nuclear with other inclusions in the body
Most common intestinal parasite in the US
Giardia lamblia
Giardia lamblia
1-trophozoite
2-Cysta
1-Trophozoite-“old man face”, ventral sucking disc attaches to GI mucosa, bilateral symmetrical paired structures, 2 anterior nuclei, falling leaf motility with 8 flagella
2-Ovoid Cyst-4 nuclei, cyst wall set off from cytoplasm, clustered nuclei and axoneme
Giardia intestinalis
1-Symptoms:
2-Epidemiology:
1-mild diarrhea to overt malabsorption syndrome…can have copius light colored, fatty stools in severe cases
2-world-wide; associated with contaminated water
*increases reported in homosexual males
Nematodes/Roundworms
General characteristics
Humans are definitive host
Thread-like, cylindrical
Buccal cavity on anterior end
Males typically smaller than the males
Intestinal Nematodes (8)
1-Enterobius vermicularis (pin worm) 2-Trichuris trichiura (whip worm) 3-Ascaris lumbricoides (large roundworm) 4-Trichinella spiralis (trichina worm) 5-Necator americanus (New World hookworm) 6-Ancylostoma duodenale (Old World hookworm) 7-Strongyloides stercoralis (threadworm) 8-Dracunculus medinensis (Guinea worm)
Cestodes/Tapeworms
General Features
Tape-like appearance
No respiratory, vascular, or digestive systems
Typically 1 intermediate host in life cycle
ALL are hermaphroditic
Tegument-outer layer that absorbs nutrient
Adults reside inhuman intestinal tract
Have scolex instead of mouth
Stroblia-tapeworm body
proglottid-individual segments that contain both male and female reproductive organs
Common Human Cestodes/Tapeworms (4)
1-Taenia solium (pork)
2-Taenia saginata (beef)
3-Diphyllobothrium latum (fish)
4-Hymenolepis nana (dwarf)
Taenia spp. Characteristics
Reside in human intestines and can range from 2-10 meters in length
Humans are the only definitive host
Ingested in undercooked meat containing cystercerci
Diagnostic stage: eggs and proglottids in feces
Trematodes/Flukes
General Characteristics
- Non-segmented, flat,and leaf-shaped
- All adults have 2 acetabula-muscular suckers
- Nutrients absorbed through tegument
2 types of Fluke/Trematodes
Hermaphroditic-reside in intestines, liver, and lungs
Unisexual-separate males and female organisms
Pathogenic Trematodes…..
1-Liver Flukes:
2-Intestinal Flukes:
3-Blood Flukes:
4-Lung Flukes:
1-Fasciola hepatica, Chlonorchis sinensis
2-Fasciolopsis buski
3-Schitosoma spp
4-Paragonimus werstermani
General lifestyle of Trematodes
Eggs are laid inhuman and then excreted in feces, sputum, or urine
All flukes that parasitize humans require a snail intermediate host
Arthropods General Characteristics
Live in/on host skin (ectoparasites)
Segmented invertebrate with chitinous exoskeleton and bilaterally pairs joint appendages
Have hemocele-body cavity filled with blood-like substance
Most common classes of arthropods
Arachnida (ticks, mites, spiders, scorpions)
Crustacea (crabs, lobster, shrimp, copepod)
Insecta (flies, mosquitos, lice, fleas, bugs)
Most common arthropod vector for disease in the US
Ticks
American dog tick/Wood Tick
Dermacentor variabilis
vector for Rocky Mountain Spotted Fever and Tularemia
Deer/Black-legged tick
often become infected with bacteria when feeding on an infected host
Vector for Lymes Disease (Borrelia burgdorferi)
Ixodes spp tick is a common vector for which common organisms?
1-Borrelia burdorferi
2-Babesia microti
3-Ehrlichia
2 major forms of Fungi?
1-Yeast-unicelllular, eukaryotic
2-Molds-multicellular, grow hyphae (filamentous), dematiaceous or hyaline
Some are dimorphic
Most fungal cultures are incubated at
30 degrees C
if a dimorph is suspected, isolate at mold phase and then culture at 37 degrees C
Characteristics that differentiate fungi from plants
- lack chlorophyll
- cell walls contain chitin
- not truly multicellular
- heterotrophic (plants=autotrophic)
Fungi morphology
Vegetative hyphae
Aerial hyphae
Vegetative: food adsorbing (under agar surface)
Aerial hyphae: may support reproductive structures (above agar surfaces)
Fungi classification
Opportunistic fungi Superficial and Dermatophytes (skin,hair,and nails) Yeast Subcutaneous mycoses (deeper tissues) systemic mycoses (organ systems)
Most common fungi in the human environment
Aspergillus spp
Opportunistic fungi are _____. ______ is often inhaled.
Since they are very ubiquitous, they can be common contaminants in ________.
Opportunistic fungi are saprobic
(live on decaying plant matter and can become airborne)
conidia is often inhaled
Since they are very ubiquitous, they can be common contaminants in sputum cultures.
Most common yeasts that cause human disease
- Candida albicans
- Cryptococcus neoformans
Which yeast is positive for germ tube production?
Candida albicans
Candidiasis
C. albicans is normal flora of the mouth, throat, vagina, and lower GI
Cryptococcosis infections
1-normal flora?
2-tied to what?
3-treatment?
1-Cryptococcus neoformans is not considered normal flora
pulmonary-pneumonia like
Cryptococcal meningitis-pulmonary infection spreads to CNS
2-tied to pigeon droppings
3-Amphotericin B with flucytocin followed by fluconazole
