2019, Issue 3 Ruminant Immunology Flashcards by Cassie Baumgarten

Vaccinating calves in face of maternal ab:

List the broad conclusions from studies that reported initial specific maternal antibody titers against important respiratory and GI pathogens:

Initial specific maternal ab titers vary greatly, depend on factors, such as:
-farm-level practices, ie dam vx and colostrum mgmt
-individual calf level factors, ie dystocia & vigor
-study-level factors, ie geography, inclusion criteria & study design

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Vaccinating calves in face of maternal ab:

The time period that maternal antibodies are present in a calf’s circulation is variable and dep on:

specific pathogen
initial dose of abies ingested and absorbed
degree to which dz challenge accelerates catbolism of abs

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Vaccinating calves in face of maternal ab:

How long are the half-lives of various maternal ab against common viral pathogens?

-unknown in the field

varies:
BRSV: 5-6.5 months
BHV1: 2-10 months
PIV3: 5-6 months
BVDV 3-7.5 months

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Vaccinating calves in face of maternal ab:

The exact ab titer that is protective against a particular disease depends on:

-pathogen
-degree of challenge
-other host, pathogen & environmental factors that influence epidemiologic triad

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Vaccinating calves in face of maternal ab:

In experimental studies, why is vaccination in the face of maternal antibodies unlikely efficacious?

Because they are unlikely to exhibit seroconversion (4-fold increase in antibody titer)

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Vaccinating calves in face of maternal ab:

What is the effect of vaccination on cell mediated immune response in calves IFOMA?

More research required
– current research says calves may be capable of generating an cell mediated immune response

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Vaccinating calves in face of maternal ab:

Are vaccines efficacious at preventing against pathogen challenge in FOMA?

**translations of vaccine efficacy against pathogen challenge in experimental models to vaccine effectiveness for disease protection against natural exposure remains to be clearly demonstrated

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Vaccinating calves in face of maternal ab:

If calves are suspected or confirmed failure of TPI, at what age are they likely to respond to parenteral vaccination?

As early as the first week of life

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Vaccinating calves in face of maternal ab:

What is a hypothesis to support vaccination in the face of maternal antibodies?

Extend the period of time when antibodies are present by vaccinating in FOMA may be beneficial for clinical protection
**hypothesis not sufficiently tested

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Vaccinating calves in face of maternal ab:

Can intranasal vaccination produce a protective immune response in seroneg/seropos calves?

-can induce relevent protection
-short duration
-variable magnitude
-viral shedding may be reduced
-immunologic priming can occur regardless of serologic status at time of intranasal vaccination

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Vaccinating calves in face of maternal ab:

Is intranasal or subcutaneous vaccination in FOMA superior?

IN vaccination may be more effective than parenteral vaccination
**responses may be variable & dz protection not complete

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Vaccinating calves in face of maternal ab:

intra-nasal vaccination in the FOMA, what are the caveats?

clinical protection is inconsistent
relatively short lived

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Vaccinating calves in face of maternal ab:

What are the potential negative effects of vaccinating in the FOMA?

-likely to inhibit seroconversion
-+/- negative effects on cell mediated immunity, pathogen shedding & risk of clinical disease

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Vaccinating calves in face of maternal ab:

what are the potential beneficial effects of vaccinating in the FOMA?

-may prolong the presence of antibodies or result in immunologic priming
-can reduce clinical symptoms after experimental pathogen challenge

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Vaccinating calves in face of maternal ab:

When would herds benefit from earlier vaccination in calves?

-inadequate pre-calving vaccination
-poor colostrum management

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Vaccinating calves in face of maternal ab:

When would intranasal vaccination be an advisable strategy?

-in herds where transfer of passive immunity is good– to circumvent interference by maternal antibodies and provide short-term disease sparing effects (with mucosal immunity)

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Vaccination management of beef cattle, delayed vaccination & endotoxin stacking:

define vaccine efficacy

the percent reduction in disease incidence and pathology in a vaccinated group compared with an unvaccinated group
or
if it has biological activity and stimulates an active immune response agents in the vaccine

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Vaccination management of beef cattle, delayed vaccination & endotoxin stacking:

define vaccine efficiency

ability of a vaccine to improve health outcomes in the production setting
-ie: clinical illness, death loss, improvement in weight gain * clear economic advantage

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Vaccination management of beef cattle, delayed vaccination & endotoxin stacking:

what are factors that compromise safety of a vaccine?

-improper time of administration (ie wildtype virus and concurrent MLV vx admin)
-improper storage and/or handling of vaccine
-disrupted physiology and immunologic status of cattle being vaccinated
-manufacturing errors that may compromise safety of a particular lot group of vaccine

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Vaccination management of beef cattle, delayed vaccination & endotoxin stacking:

What are cellular components that make up endotoxins?

lipopolysaccharide (LPS) cell membrane
peptidoglycans
lipoproteins
other bact components

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Vaccination management of beef cattle, delayed vaccination & endotoxin stacking:

define endotoxin

major components of outer cell membrane of gram neg bacteria
-released from bact cell walls when cell is killed or lysed

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Vaccination management of beef cattle, delayed vaccination & endotoxin stacking:

define exotoxin

diffusible proteins that are primarily produced & actively released from bact during log-phase growth
-heat-liable, highly antigenic proteins
-released when cell walls are lysed

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Vaccination management of beef cattle, delayed vaccination & endotoxin stacking:

What part of bacteria makes a vaccine toxoid?

exotoxins– chemically or heat inactivated

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Vaccination management of beef cattle, delayed vaccination & endotoxin stacking:

what are bact exotoxins classified as (according to mode of action)

Type I: membrane acting toxins that bind surface receptors & stimulate transmembrane signals

Type II: membrane damaging toxins that directly affect cell membranes from forming pores or disrupting the lipid bilayers of cell membranes

Type III: toxins that modify an intracellular target molecule by translocating an active enzymatic component into the cell

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Vaccination management of beef cattle, delayed vaccination & endotoxin stacking: Define pathogen associated molecular patterns (PAMPS)

highly conserved structures present on many different microorganisms recognized by the immune system (ie. Lipid A)

Vaccination management of beef cattle, delayed vaccination & endotoxin stacking: Define pattern recognition receptors (PRRS)

receptors that recognize PAMPs

Vaccination management of beef cattle, delayed vaccination & endotoxin stacking: Pattern recognition receptors (PRRs) are divided into what functional groups:

1. circulating humoral proteins, such as endotoxin and complement proteins 2. endocytic receptors that are expressed on the cell surface and mediate endocytosis 3. signaling receptors, such as toll-like receptors that are expressed on surface of the cell

Vaccination management of beef cattle, delayed vaccination & endotoxin stacking: adverse reactions with endotoxin containing bacterins occur due to a phenomenon known as:

endotoxin stacking

Vaccination management of beef cattle, delayed vaccination & endotoxin stacking: When is there increased risk of adverse reactions with endotoxin stacking?

When 2 or more gram- negative bacterins are administered concurrently **should be avoided when designing vaccine protocols

Vaccination management of beef cattle, delayed vaccination & endotoxin stacking: What is a possible benefit of endotoxin exposure (low dose)?

endotoxin exposure stimulates B cell differentiation & enhances phagocytic activity, helping host animal immune system to recognize and eliminate invading pathogens more rapidly & effectively

Vaccination management of beef cattle, delayed vaccination & endotoxin stacking: what is the negative side effect of high dose exposure to endotoxin?

Can elicit a severe febrile & hypotensive response that rapidly leads to multiorgan failure, septic shock, & death

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response what clinical syndromes are associated with M bovis?

bovine respiratory disease mastitis otitis media conjunctivitis arthritis genital tract infections decubital abscesses

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response M. bovis a primary inhabitation of what?

respiratory mucosal surfaces ** like other opportunistic pathogens of BRD complex

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response when treating Mycoplasmas, what is key about their cell physiology?

they lack a cell wall

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response What are characteristics of Mycoplasma bovis cell membrane proteins?

-ability to adhere to a wide variety of cell types -surface antigen variation -biofilm production

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response What determines the virulence of different strains of M. bovis?

-their ability to adhere to epithelial cells **less pathogen strains having lower adherence rates

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response Why are M. bovis variable surface proteins (VSPs) important immunologically?

-antigenic variation-- undergo high frequency phase & size variation -biofilm formation --> evading host immune system

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response Besides VSPs, what other virulence factors assist in mycoplasma evading the immune system?

hydrogen peroxide production-- oxidative injury to tissue/cytotoxicty

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response Experimental M. bovis respiratory infection stimulates which immune response?

humoral response **median seroconversion of 21 days

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response In calves, the adaptive immune responses to M. bovis have which cell type bias and what immunoglobulin predominates in serum?

T-helper (Th2) bias with IgG1

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response In calves experimentally induced with M. bovis pneumonia, wwhich cell types predominate?

IgG1 producing plasma cells

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response besides IgG production, M. bovis also stimulates the production of other antibodies, and where?

IgA production in the upper and lower respiratory tract

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response Which humoral response are most efficient at M. bovis clearance from the respiratory tract & mammary gland?

** more work is needed --mammary glands that are resistant to reinfection have higher concentrations of IgA and IgG

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response Effective phagocytosis of M bovis by bovine neutrophils & macrophages depends on opsonization. How does this effect the clearance of M. bovis by the immune system?

The humoral immune response in M bovis is skewed towards IgG1 production, which is less effective for neutrophil phagocytosis killing than IgG2

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response List the strategies M. bovis utilizes to evade the immune system:

1. variation in surface antigens-- partly by antibody mediated selection pressure 2. formation of biofilms-- protection from opsonization & phagocytosis 3. Expresses proteins that damage host immunoglobulins-- mycoplasma Ig binding protein & Mycoplasma Ig protease

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response What is the most abundant immune cell type in the lungs, middle ear & joints of cattle with M bovis associated dz?

Neutrophils

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response How do neutrophils show impaired function (in vitro) after exposure to M. bovis?

-adheres to cell surface w/o being phagocytosed -inhihibits respiratory burst activity & nitric oxide production -induce production of inflammatory cytokines & enhances neutrophil apoptosis -Evades neutrophil NET killing

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response Which cell types are most important in driving downstream immune responses in BRD?

alveolar macrophages

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response which cytokines does M bovis stimulate macrophages to produce?

IFN gamma TNF alpha IL-10 **variable cytokine production at each tissue

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response What type of MHC class presentation is downregulated in chronic M. bovis infections?

MHC class II ** may contribute to ongoing, ineffective local immune responses

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response M. bovis delays apoptosis in which immune cells?

monocytes & alveolar macrophages

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response M bovis can survive in which host cells?

-bovine alveolar macrophages -lymphocytes -RBCs -epithelial cell types

Mycoplasma bovis: interactions with the immune sys & failure to generate an effective immune response what plays an important role in the development of BRD?

nasopharyngeal microbiota composition & stability

Nutraceuticals as an alternative strategy for the use of antimicrobials: Define nutraceutical

hybrid of nutrition & pharmaceuticals

Nutraceuticals as an alternative strategy for the use of antimicrobials: what are the classes of nutraceuticals?

probiotic prebiotic phytonutrient polyunsaturated fatty acid

Nutraceuticals as an alternative strategy for the use of antimicrobials: what is a problem with nutraceuticals?

lack governmental regulatory oversight by the FDA-- b/c classified as dietary supplements --product label statements regarding composition, dosage, effectiveness, & quality are not necessarily independently validated or standardized

Nutraceuticals as an alternative strategy for the use of antimicrobials: what are common microorganisms used commerically?

lactobacillus or other lactic acid producing bacteria Bifidobacteirum sp bacillus spp saccharomyces cerevisiae

Nutraceuticals as an alternative strategy for the use of antimicrobials: what are important considerations when supplementing probiotics?

-dose (colony-forming units) -duration of supplementation -age of the animal

Nutraceuticals as an alternative strategy for the use of antimicrobials: what are the mechanisms that are proposed to support the use of probiotics?

-competitive exclusion-- more good bacteria present on GI mucosa to outcompete the bad bacteria -improve GI mucosal immune system -increased butyrate production (directly or indirectly through lactic acid producing bacteria)

Nutraceuticals as an alternative strategy for the use of antimicrobials: does oral probiotic administration assist in mammary gland health?

**there is data lacking to support their use in mammary gland health, suggested intramammary infusions

Nutraceuticals as an alternative strategy for the use of antimicrobials: define prebiotics

indigestible carbohydrates, including many oligosaccharides & fructans

Nutraceuticals as an alternative strategy for the use of antimicrobials: by which mechanisms are prebiotics proposed to improve animal health

- serve as an energy source for commensal bacteria in rumen/lower GIT -immunomodulatory effects -ability to bind gram negative bacterial pathogens -adsorbing certain mycotoxins

Colostrum management for dairy calves in cattle, what kind of placenta separates the maternal & fetal blood supplies

syndesmochorial placenta

Colostrum management for dairy calves what are the benefits of successful passive transfer of immunity in calves

-reduced risk for preweaning morbidity & mortality -reduced mortality in postweaning period -improved rate of gain -reduced age at first calving -improved first & second lactation milk production -reduced tendency for culling during the first lactation

Colostrum management for dairy calves fresh colostrum contains highest concentrations of which leukocytes in cattle?

macrophages lymphocytes

Colostrum management for dairy calves in the colostrum management, what processes remove leukocytes?

freezing heat treatment

Colostrum management for dairy calves what components of colostrum are critical for thermogenesis & body temperature regulation in calves?

fat & lactose

Colostrum management for dairy calves what component of colostrum serves to protect Ig & other proteins form proteolytic degradation in the intestine of the neonatal calf?

Trypsin inhibitor

Colostrum management for dairy calves what are bioactive components of colostrum with antimicrobial activity

lactoferrin lysozyme lactoperoxidase

Colostrum management for dairy calves what are the 2 major factors that affect the consumption of IgG?

1. quality of colostrum 2.volume of colostrum

Colostrum management for dairy calves what are factors that affect the absorption of Ig molecules into circulation

-quickness with which the first colostrum feeding is provided after birth -bact contamination of colostrum -metabolic status of the calf

Colostrum management for dairy calves At what value is high colostrum considered high quality?

IgG>50 g/L

Colostrum management for dairy calves At which age of cow is considered to have higher quality colostrum?

cows from third lactation and older **still recommend testing colostrum quality

Colostrum management for dairy calves how does season of calving affect colostrum quality?

high temperature can reduce colostrum quality **suggested to be associated with reduced DMI or Dec mammary blood flow

Colostrum management for dairy calves what are the benefits of vaccinating pregnant cows within 3 to 6 weeks preceding calving?

increased concentrations of ag-specific protective colostral antibodies -increased passive antibody titers in calves of vaccinated dams, specific for common pathogens (Pasteurella haemolytica, Salmonella typhimurium, Escherichia coli, rotavirus & coronavirus)

Colostrum management for dairy calves how does dry period length effect colostrum quality

cows with excessively short dry periods produce colostrum with lower IgG concentration and lower yields of colostrum (<21 days)

Colostrum management for dairy calves How does timing of collection of colostrum after calving affect colostrum quality?

Ig concentration is highest immediately after calving **begins to decrease over time if harvest is delayed

Colostrum management for dairy calves if using a colostrometer, what is the level is colostrum considered high quality?

specific gravity >1050 approximately IgG >50g/L

Colostrum management for dairy calves what factors affect colostrometer reading?

-fat content -colostrum tempterature

Colostrum management for dairy calves When using a Brix refractometer, what is the level of good quality colostrum?

18-23% is good quality colostrum

Colostrum management for dairy calves in comparison to colostrometer to brix refractometer, which is a better measurement of colostrum quality?

**Brix refractometer b/c its less affected by temperature & more durable than glass colostrometer

Colostrum management for dairy calves what is the volume of recommended colostrum to be fed to a calf?

10-12% of bodyweight (3-4 L for Holstein calf)

Colostrum management for dairy calves What is the recommended delivery method for administering colostrum to calves?

bottle or tube feeding bottle-- need to ensure get amount of colostrum tube feeding-- doesn't stimulate esophageal groove reflex directly from dam not recommended due to increased FPT

Colostrum management for dairy calves How are immunoglobulins absorbed from the GIT of neonates?

pinocytosis

Colostrum management for dairy calves For time to first colostrum feeding, what is the optimal time to administer?

Aim within 1 to 2 hours after birth

Colostrum management for dairy calves Is there any value to a second administration of colostrum after the initial that was administered w/in 2 hours of parturition?

yes, a study showed that a second feeding of a 1:1 colostrum/milk mixture or colostrum within 12 hours of age calves at a higher IgG level

Colostrum management for dairy calves Is there any value in feeding colostrum or transition milk after gut closure?

bioactive compounds, such as hormones and oligosaccharides that stimulate development of GIT, with improvement in amount of diarrhea, respiratory dz, etc. etc.

Colostrum management for dairy calves bacteria levesl in colostrum should be less than what value?

less than 100,000 CFUs

Colostrum management for dairy calves heat treatment of colostrum eliminates what pathogens?

E coli Salmonelal enteritidis Mycoplasma bovis reducing exposure to MAP

Colostrum management for dairy calves What are pros and cons of colostrum supplements or replacement productions?

Pros: availability, consistency, conveniences, prevention of pathogen spread Cons: colostrum supplements do not replace colostrum, the quantity/volume needed for CRs/CSs, variable absorption/performance among products

Colostrum management for dairy calves what is the gold standard for evaluating passive transfer in calves?

radial immunodiffusion (RID) assay

Colostrum management for dairy calves When using serum total protein to assess passive transfer, to what age can this measurement be used?

24 hours after first colostrum feeding to 10 days of age

Colostrum management for dairy calves What values for failure of passive transfer for immunity (association of low morbidity and higher values of serum IgG)?

IgG <10 g/L Brix: 8.1-8.8 serum TP:5.1-5.7