Exam #1 Flashcards
___ refers to the ability of a virus to cause disease in a host (harm to the host). The virus which causes disease is called a ___. ___ is the manner/mechanism of development of a disease.
Pathogenicity
Pathogen
Pathogenesis
The term ___ is used as a quantitative or relative measure of the degree of pathogenicity of the infecting virus.
Virulence
What are 3 routes of entry of viruses into host-skin? And what kind of entry are these?
Transcutaneous injection
- bite of arthropod
- bite of infected animal (rabies)
- contaminated objects (needles)
What are some routes of entry of viruses into host-mucous membranes?
Conjunctiva
oropharynx
genitourinary tracts/rectus
What route of entry of viruses are host-GI tract?
Gastrointestinal tract
viruses in contaminated food and water
How do viruses spread in the host from local infection of epithelial surfaces to subepithelial invasion and lymphatic spread?
- viruses may reach subepithelial layer/underlying tissue from epithelial surfaces
- to do this, viruses should overcome local host defense
How do viruses spread in the host from subepithelial invasion and lymphatic spread to blood stream and then spread via blood stream?
In subepithelial tissues, viruses get access to lymphatics, phagocytic cells and tissue fluids.
These may help carry virus to the blood stream.
__ is the presence of viruses in the blood.
Viremia
What are the two ways primary viremia can happen?
- ) spread of the virus infection to blood from subepithelial tissue/lymphatics
- ) directly inject in blood, through bite of mosquitoes or syringes
What is the process of secondary viremia?
the virus has replicated/multiplied in major organs and once more entered the circulation.
What is disseminated infection?
infection spreads beyond the primary site of infection
What is systemic infection?
if a number of organs or tissues are infected by a virus.
What are 3 ways that a virus can spread to the central nervous system (brain, spinal cord) via nerves?
- ) through peripheral nerves (rabies)
- ) through receptor neurons in the nasal olfactory epithelium
- ) virus can cross blood-brain barrier & infect CNS (west nile)
A ___ virus is a virus that can infect neural cells. Infection may occur by neural or hematogenous spread. it has an affinity for the central nervous system.
Neurotrophic virus
A ____ virus is a virus that enters the central nervous system (spinal cord and brain) after infection of a peripheral site.
Neuroinvasive virus
A __ virus is a virus that causes death of nervous tissue, manifested by neurological symptoms and often death.
Neurovirulent virus
What are the results of a local spread of a virus on epithelial surfaces?
- can cause localization infection
- may or may not proceed to subepithelial layer/underlying tissue
What is tropism?
the specificity/affinity of a virus for a particular host tissue.
What is a pantropic virus?
they can replicate in more than one host organ/tissue
What are some virus-cell interactions?
- inhibition of host-cell nucleic acid synthesis
- inhibition of host-cell RNA synthesis (transcription)
- inhibition of host-cell protein synthesis
- cytopathic effects of “toxic” viral proteins
- interference with cellular membrane function
what are some outcomes of a viral injury?
- lysis/bursting
- apoptosis
- oncoviruses/transformation (cancer)
- persistent infection
- immune supression
What are oncoviruses?
some viruses can cause cancer, and are known as oncovirses or oncogenic viruses
What is a persistent infection?
some viruses do not cause immediate death of infected host cells, but cause persistent infection. many of these viruses remain latent or dormant in host cell or long periods, escaping detection by the host immune system.
What is a vesicle?
a fluid filled sac
What is an ulcer?
opening in the skin caused by sloughing of necrotic tissue, extending past the epidermis
What is a nodule?
solid tumorous mass
What are warts?
they are benign skin growths that appear when a virus infects the top layer of the skin.
What is erythema?
reddening of skin
What happens when a viruses injures the GI tract?
Viruses can enter either through ingestion or from blood, systemic infection. Then there is destruction of intestinal enterocytes. Which leads to malabsorption and diarrhea. Lastly there will be dehydration, acidosis and hemoconcentration.
What happens when a virus injures the respiratory tract?
- inflammation
- obstruction of air passage
- hypoxia & respiratory distress
What happens when a virus injures the central nervous system?
- lytic (destruction/bursting) infections of neurons
- neuronal necrosis (necrosis is death of body tissue)
- neuronphagia (killing/devouring of neuronal cells by phagocytic cells)
- perivascular cuffing (inflammatory cells around blood vessels in CNS)
Viral Injury to the central nervous system via progressive demyelination.
this is when the virus destroys the myelin sheath on the nerve. this results in nerve impulses not being able to go through
What is it called when you have a viral infection of the fetus and what happens?
Teratogenic viruses: cause developmental defects of embryo or fetus after in-utero infection
Viral Injury to the central nervous system via neuronal vacuoluation.
in prion disease. it causes vacuoles in the proteins that look like bubbles.
what are the 3 groups of eukaryotic organisms that affect health and wellbeing of animals?
protozoa
helminths
arthropods
What are the 3 different categories that fall under helminths (helminthology)?
nematode: roundworm
cestode: tapeworm (flatworms)
trematode: fluke (flatworms)
what are arthropods (entomology)?
arachnids and insects; ectoparasites
What are ectoparasites?
- lives on the host
- causes infestations
What are endoparasites?
- lives in the host
- cause infections
Definite host
Harbors adult or sexual stage of the parasite
Intermediate host
Harbors larval or asexual stage of the parasite
Incidental host
An unusual host, unnecessary for the maintenance of the parasite in nature. this parasite can live with or without the host. causes lot of damage
What is host specificity?
Parasites have specificity for particular definite and intermediate hosts. Often parasite life cycles can only be completed in a particular host.
What are some common routes of parasite entry?
ingestion sink or mucosal penetration transplacental (prenatal) transmammary (milk) arthropod bite (vector) sexual contact
What tapeworm can be more than 10 yards and not have a large or detectible effect or on the host?
Taenia saginata
What are some characteristics of infective dose and exposure for protozoa and helminths?
Protozoa: they multiply in the host very rapidly causing harm
Helminths: adult worms do not multiply in the definitive host. worms die over time, unless the host is re-exposed. The severity of disease is proportional to worm load introduced into the host.
What parasite can actively penetrate unbroken skin?
blood fluke
Schistosomisis: cercaria
What are some ways of attachment for parasites?
Mechanical or biting mouthparts
- oral cavity (capsule)
- attachment organs
- suction disk
- biting mouthparts
- direct penetration
Molecular interaction
What parasite can penetrate tissue?
whip worm
Trichuris vulpis
the thin end of the parasite is the one that penetrates the intestine wall
What are two way a parasite can cause cell and tissue damage?
- mechanical damage
- toxic products
What are some results of mechanical damage from a parasite?
- blockage of internal organs
- pressure atrophy (can go in cell)
- migration through tissues
What parasite lives in the intestine of horses?
Nematode
Parascaris equorum
ascaris
What parasite is found in the tissue and cause inflammation
Toxocariasis
What are some toxic parasite products?
- destructive enzymes
- endotoxins
- toxic secretions
What are some ways a host can have a lost of nutrients from a parasite?
- competition with hosts for nutrients
- interference with nutrient absorption
- nutrient loss
Definition of immunity
the condition that permits either natural or acquired resistance to disease
What two initial mechanisms that animals are borns with to provide protection to from invaders? and what provides prolonged immunity?
physical barriers
innate immunity
adaptive immunity
What are the two types of adaptive immunity?
- ) antibodies
2. ) cell-mediated immunity
What are some physical barrier to protect animals against microbial invasion?
skin
self-cleaning
normal flora
What are some examples of innate immunity to protect animals against microbial invasion?
inflammation
defensins
lysozyme
What are some examples of adaptive immunity to protect an animal’s body against microbial invasion?
antibody production
cell-mediated immunity
more efficient but take longer to develop
What are two types of innate immunity?
- acute
- chronic (stays for longer period of time)
What are some main differences between innate immunity and adaptive immunity?
Innate immunity
- non-specific
- not dependent on the antigen
- immediate/rapid
- does not leave any memory
Adaptive immunity
- antigent-specific
- delayed in time
- leaves memory
What are two subsystems of the innate immune systems?
Cells
- detect invaders
- eat invaders
- kill invaders
- kill virus-infected cells
Molecules
- bind and kill invaders
- coat invaders so cells can kill them
- block microbial growth
- prevent microbial spread
- mobilize body defenses
What is the process for adaptive immune response for intracellular and extracellular?
the first 2 steps are the same for both
Antigen-processing cells-> Antigen-sensitive cells -> memory cells
Extracellular-> memory cells & antibody-producing cells-> antibody production
Intracellular-> memory cells & effector cells -> cell-mediated immunity
both result in antigen elimination
___ is the production of immune cells.
Hematopoiesis
produced every day in the bone barrow
red blood cells
What are the 3 major lineages of Hematopoiesis?
- ) Erythroid (erythrocytes and platelets)
- ) Myeloid
- ) Lymphoid
What falls under myeloid?
- Granulocytes (neutrophils, eosinophils, basophils)
- Mast cells
- Monocytes
- Macrophages
- Myeloid dendritic cells
What falls under Lymphoid?
- Lymphocytes (T and B cells)
- Natural Killer cells
___ are the only cells in the body capable of specifically recognizing and distinguish different antigens.
Lymphocytes
What are the two types of Lymphocytes?
B lymph
T lymph
Where do B Lymphocytes mature?
Birds-> Bursa of Fabricius
Mammals-> Bone barrow
and GI tract
Where do T Lymphocytes mature?
Thymus
precursors arise from bone marrow
Adaptive immunity is mediated by ____ mainly found within ____ organ
lymphocytes
lymphoid
What are the primary lymphoid organs?
thymus
bursa
peyer’s patches
bone marrow
What are the secondary lymphoid organs?
tonsils spleen lymph nodes peyer's patches bone marrow
Where do B & T cells finish maturation?
the primary lymphoid organs
once they are mature they migrate to the second lymphoid organs
What is the time of development for primary and secondary lymphoid organs?
Primary: early in embryonic life
Secondary: late in fetal life
What happens if you were to remove a primary or secondary lymphocyte?
primary: loss of lymphocytes
secondary: no or minor effects
What are the diagnostic methods?
- what are the host species
- site of infection
- size of the parasite
SIS
What are 3 diagnostic methods
- understand the parasites
- select the samples to collect
- select the appropriate diagnostic methods
What is the name of the class that has roundworms?
Nematoda
What are the two classes that fall under flatworms/platyhelminthes?
Cestoda (tapeworms)
Trematoda (flukes)
What are the main characteristics of Nematodes?
- free-living or parasitic
- elongated/cylindrical
- alimentary canal present
- sexes usually separate
What are the main characteristics of Cestodes?
- flat body and alimentary canal (they absorb nutrients)
- scolex
- strobila (body) with proglottids
- each proglottid-hermaphroditic (segment of the tapeworm)
What are the main characteristics of trematodes?
- Dorso-ventrally flattened
- leaf-like
- oral and ventral suckers
What are the main identifiable characteristics of insects?
- 3 pairs of legs
- head, thorax, abdomen
- antenna
What are some examples of insects?
flies
fleas
lice
What are some characteristics of Arachnids?
ticks
mites
What are the main identifiable characteristics of Arachnids?
- 4 pairs of legs
- cephalo-thorax and abdomen
- no antennae, but palps
What are some important characteristics of protozoa?
- unicellular, eukaryotic animals
- classified based on mode of locomotion
How is locomotion accomplished by Protozoa?
- pseudopodia
- flagella
- gliding movements
- cilia
What is the cycle of viral pathogenesis?
- ) entry and primary replication
- ) spread & infection of target organs
- ) virus/cells interactions
- ) organ and tissue injury
- ) shedding & trophy (increase in # of viruses)
What is monocyte trafficking?
a mechanism of viral spread. The virus hides inside the monocyte, which crosses tissue barriers including the BBB
Pathogenicity is an absolute factor of a virus, while virulence is a variable factor.
A.) True
B.) False
A.) Ture
A virus that enters the CNS from a peripheral site but does not cause damage is referred to as a
A.) Neurotropic and neuroinvasive
B.) Neuroinvasive and neurovirulent
C.) Neurotropic and neurovirulent
A.) Neurotropic and neuroinvasive
The primary effect of interferons is:
a. ) antiviral
b. ) antibacterial
c. ) antiparasitic
d. ) antifungal
a.) antiviral
How does the adaptive immune system recognize self from non-self?
a. ) MHC
b. ) antibodies
c. ) toll-like receptors
d. ) T-cell receptors
a, b, d
Insects are ectoparasites that cause infections
a. ) true
b. ) false
b.) false
Which helminths are hermaphroditic?
a. ) roundworms
b. ) flatworms
c. ) flukes
b.) flatworms
cestodes
Which helminths have an incomplete alimentary tract?
a. ) trematodes
b. ) nematodes
c. ) cestodes
a.) trematodes
What parasites cause infestations? (choose all that apply)
a. ) nematodes
b. ) cestodes
c. ) insects
d. ) trematodes
e. ) ticks
f. ) mites
c, e, f
What parasites have a direct life cycle?
a. ) roundworms
b. ) flatworms
c. ) flukes
a.) roundworms
A young puppy has a heavy nematode infection in its small intestine that results in intussusception. What kind of virulence is this?
a. ) loss of nutrients
b. ) attachment
c. ) mechanical damage
d. ) penetration of anatomic barriers
c.) mechanical damage
A small dog with a severe tick infestation experiences anemia. What kind of virulence factor is this?
a. ) loss of nutrients
b. ) attachment
c. ) mechanical damage
d. ) penetration of anatomical barriers
d.) penetration of anatomical barriers
Cyathostomins hide inside their equine host and emerge synchronously in the spring causing breakdown of the mucosal lining of the large intestine. what kind of virulence is this?
a. ) loss of nutrients
b. ) attachment
c. ) mechanical damage
d. ) penetration of anatomical barriers
a.) loss of nutrients
