Immunology and Vaccination of Dairy Cattle Flashcards
What is the importance of colostrum?
- a calf is born with no antibody in serum
- immune system is functional, but naive and immature
- normal flora is not yet well-established
- achieving adequate passive transfer of colostral Ab is the single most important factor influencing dairy calf survival
How long prior to calving are antibodies transferred into colostrum?
starts 5 weeks prior to calving and peaks 2 weeks prior to calving
Which pathogens do we commonly vaccinate cows against in order to provide passive immunity to calves?
- BVDV, BHV1, BRSV, PI3
- Major clostridial dzs
- ETEC
- core gram- vax to reduce severity of coliform mastitis
- Campylobacter
- 5 Lepto serovars
How long do maternal antibodies persist in calf serum?
persist in serum for 1-6 months
What are the advantages and disadvantages of modified live vaccines?
A:
- strong and long acting
- can be given IN or PO
- less risk of hypersensitivity
- may stimulate interferon
- humoral and CMI
DA: immunosuppressive
- risk of dz, transmission
- perpetuation of Ag in population
- abortion
- most need to be reconstituted
Describe the characteristics of primary and secondary immune responses
Primary:
- barriers - skin, mucous mm, secretions, resident microflora
- cellular, cytokine, + protein defenses: interferons, defensins, chemokines, complement, NK cells
Secondary:
- cellular and humoral defenses: antibodies, cytokines, chemokines, T helper cells, cytotoxic T cells
When are boosters indicated?
- usually rx for both MLV and KV
- exception is Brucella abortus
- KV and BRSV MLV require a booster after the initial vax
- 1st time KV administered > primary response
- primary response = fairly short lived and not very strong, predominant Ab = IgM
- 1st time KV administered > primary response
When is the period of reduced immune responses in young calves?
from day 2 to 4-5 weeks of age; corresponds when maternal T cells are disappearing from the calf
What route of vaccination is most effective in very young calves?
intranasal or oral
What is maternal antibody interference?
- maternal antibodies that have not left the neonate’s serum yet interfere with the calf’s ability to mount an appropriate immune response to the Ag in the vaccine
- mostly for disease in which humoral immunity is the primary protective mechanism
- depends on the level of maternal Ab
When should vaccination be completed by in relation to the risk period for disease?
complete vaccination at least 10-14 days (30d if possible) prior to risk period
What are factors to consider when choosing a vaccine?
- look for published scientific data
- look at the label
- list duration of immunity studies?
- list efficacy studies?
- cost/benefit
- endotoxin load:
- adults > max 3 gram - Ag
- young-stock > max 2 gram - Ag
What are the label claims you might see on a vaccine?
- Prevention of infection
- Prevention of disease
- Aid in disease prevention: prevent dz by a clinically sig amount but less than that required to support a claim of dz prevention
- Aid in disease control: alleviates dz severity, reduces dz duration, or delay dz onset
- Other claims: beneficial effects other than direct dz control, such as reduction of pathogen shedding
What are the vaccine antigens that are recommended for all or most dairy herds, both bacterial and viral?
- IBR
- PI3
- BRSV
- all 3 of these = IN MLV in calves, no IBR MLV for pregnant cows
- BVDV - types 1 and 2
- systemic KV or MLV (NOT in pregnant cows)
- Clostridium spp.
- Lepto spp.
- ETEC
- Campylobacter fetus ssp. venerealis
Which is the host-adapted serovar of Leptospira?
Harjo - causes early embryonic loss
Which clostridial diseases/pathogens should be routinely vaccinated against?
- C. chauvoei - blackleg
- C. novyi - black dz
- C. septicum - malignant edema
- C. sordellii - gas gangrene
- C. perfringens types C and D - enterotoxemia
When is vaccination against Brucella abortus used? What are special requirements related to use of this vaccine?
- for regulatory reasons or if importing animals into herd from higher risk area
- must be USDA accredited to administer, and calves are given a special ear tag, record submitted to State Vet
What should you evaluate when trouble-shooting a vaccine efficacy issue?
- not following protocol
- timing, site or route of admin of primary injections and boosters
- change in exposure risk?
- change in immune status/stress/nutrition?
- storage
- vaccine handling
- ML vaxs esp. susceptible - use immediately after reconstituting
- keep it cool
What are the factors that affect disease resistance?
- Pathogen
- antigenic variation/virulence factors
- how it is transmitted
- Host
- genetics
- age
- concurrent illness
- level of passive immunity
- Management
- Pathogen exposure
- Housing
- Nutrition
- Transportation
- Management of weaning/calving to minimize stress
- Internal and external parasite control
- Vaccination
What are the advantages/disadvantages of killed vaccines?
A:
- unlikely to causes dz, safe for immunosuppressed or pregnant animals
- not immunosuppressive
- stable in storage
- no transmission
DA:
- incomplete inactivation
- shorter immunity
- only parenteral route
- hypersensitivity
- adjuvants - local reactions
- booster essential
- generally more costly
What are the advantages of intranasal/oral modified live vaccines?
A:
- local specific protection (esp. IgA) at the mucosal surface and priming of the systemic immune system
- can stimulate good immunity in the face of maternal Ab (BRSV and IVR)
- stim non-specific local innate immune response
DA:
- only available for a few pathogens - rotavirus/coronavirus, IBR, PI3, BRSV
The response seen after a booster vax is what kind of response? Describe what this means.
a secondary or anamnestic response
- much stronger and long lived
- primarily IgG
- more memory made in response to the booster
Why do you not typically need boosters with MLV vaccines?
the primary vaccine usually stimulates the secondary response without needing a booster since the virus or bacteria is growing in the animal, as long as the animal is capable of mounting an immune response the first time the vaccine is given
What vaccines are not blocked by maternal antibody?
- BRSV
- BHV-1
- Parainfluenza virus
- Lepto
What vaccinations are blocked by maternal antibody due to the primarily humoral immune response stimulated by the antigen?
- BVD virus
- Mannheimia haemolytica
- Pasteurella multocida
