Vaccinating the Young Calf

Keeping the calf immune system in balance against Bovine Respiratory Disease (BRD).

Editor’s Note: The following is adapted from a presentation given by Chris Chase, DVM, Ph.D., Professor in the Department of Veterinary Science at South Dakota State University, during the BRD Battle Plan Webinar sponsored by Boehringer Ingelheim Cattle Health.

The immune system’s major job is to maintain health. It does that in a partnership with immune cells in the mucosa, respiratory tract, digestive tract and in the microbiome. There’s a continuous interaction that results in optimal animal welfare. This system is constantly interacting to maintain animal health.

In the past, the industry has thought of a barrier like the skin as a static structure. In fact, the mucosa is the largest organ in the body. One of the first parts of the immune system that kicks into gear is the innate immune system, and inflammation is really key. That’s how it mobilizes the immune system and mobilizes the adaptive immune system. Keeping inflammation at the right level is important when it comes to health. Actually, innate immunity and adaptive immunity are interacting all the time.

With a healthy microbiota, the animal has a more effective barrier to keep pathogens out. With a depleted microbiota, the commensal organisms become depleted and make it easier for pathogens to breach the barrier. A similar process happens in the respiratory tract’s mucosal barrier.

The immune system is a big energy consumer. If the animal can keep that system from working too much, then it can put that energy into production.

Inflammation and immunity

When it comes to innate immunity, inflammation is really important. Inflammation helps trigger inflammatory cytokines to draw cells to the infection. Inflammation starts out as a local effect, then regional effect and then there’s a systemic effect. Another thing we see is the effect on the central nervous system. The producer may notice animals act listless or have a drop in appetite. That’s a normal response. That sickness behavior tells producers the vaccine response is happening.

We expect to see inflammation, but there are parts of inflammation that are not really good. In the end, it’s really a balancing act. We want just enough response to control disease. Too much of a good thing response, we see immune pathology. Too little response allows the pathogen to “win.”

Primary vaccinations for calves

We can expect a proinflammatory response to prompt some sickness behavior. There are really two pieces of the primary acquired immune response: antigen presentation by, and dendritic cells that results in, T-cell activation, which turns on T cell help and killing and also B cell activation and antibody production. Parenteral vaccines can induce mucosal immunity. The kind of adjuvant makes all the difference in the world.

To test this theory, a research team including Chase evaluated three groups of vaccinated calves. The team studied colostrum-fed dairy and beef calves that were vaccinated at about 30 days of age with either:

1. An adjuvanted parenteral vaccine containing modified live bovine viral diarrhea virus (BVDV) type 1 and type 2, bovine herpesvirus 1 (BHV-1), bovine parainfluenza type 3 virus (PI3) and bovine respiratory syncytial virus (BRSV) and M. haemolytica toxoid (Group 1)
2. An intranasal temperature-sensitive BHV-1, BRSV and PI3 concurrently with a parenteral vaccine containing modified live BVDV type 1 and type 2 and M. haemolytica toxoid (Group 2)
3. A placebo (Group 3)

The calves were challenged about 150 days post vaccination intranasally with BVDV 1b and then seven days later intratracheally with M. haemolytica. The strain of BVDV, maternal interference and vaccine interference all played a role in the outcome of this study.

The 1b strain of BVDV is between 60 to 75 percent of the isolates seen in the U.S. It’s the major player in American cattle herds. In the vaccines on the market, the “Singer” strain of BVDV 1a provides better cross protection, which was the strain present in the study’s parenteral vaccine.

With some parenteral vaccines, there’s an age factor. The older a calf gets, the more response the calf is going to be to the vaccine.

Vaccine interference also can play a role in immune response in calves. That’s where you may have two different licensed vaccines administered concurrently that interfere with the respective component responses. A licensed vaccine is licensed for its specific components, but not with other vaccines’ components. This was first recognized about 30 years ago. A single licensed product can help eliminate the possibility of interference.

Balancing maternal antibodies with vaccination timing

The cattle industry has long sought to achieve the “perfect” timing for calf vaccinations. Too soon interferes with maternal antibodies. Too late leaves a gap in protection. Based on recent research, Chase advises producers to vaccinate calves as early as 30 days with a parenteral vaccine containing the right strain of BVDV 1b and an adjuvant proven to work in the face of maternal antibodies.

References:

1 Perkins-Oines S, Dias N, Krafsur G, et al. The effect of neonatal vaccination for bovine respiratory disease in the face of a dual challenge with bovine viral diarrhea virus and Mannheimia hemolytica. Vaccine. 2023;41(19):3080-3091.

Key Points:

• One of the most widely accepted disease protection measures against BRD in cattle is maternal antibody transference at birth.
• However, maternal antibodies are often at odds with, and may inhibit, vaccination by neutralizing antigens in the vaccine and preventing calves from developing an effective immune response.
• To prevent maternal antibody interference, producers typically vaccinate calves after antibody concentrations decrease. This antibody decline can allow for a gap in BRD pathogen protection within the herd depending on maternal antibody decay and induction of active immunity by vaccination when calves are vulnerable to infection.
• Protocols utilizing an intranasal and a parenteral vaccine concurrently are utilized by some veterinarians and producers to ensure vaccination against potential pathogens related to BRD.
• In one study, calves vaccinated with an adjuvanted parenteral vaccine had decreased severity of disease and viremia after a dual BVDV and M. haemolytica challenge.

Photo credits:

istockphoto.com/branex

istockphoto.com/Diane Kuhl