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
