BEST MANAGEMENT PREACTICES FOR VACCINATIONS
U
BY DR. JUAN M. CAMPOS KRAUER niversity of Florida, College of
the pathogen known as antigens. The next
Veterinary Medicine, Dept. of
time the immune system recognizes these
immunocompromised individuals.
Large Animal Clinical Sciences
antigens, it will immediately trigger the
Inactivated vaccine: Some vaccines contain
& Dept. of Wildlife Ecology and Conservation. Cervidae Health
production of specific antibodies by specialized cells, which will work to destroy
inactivated but previously virulent microorganisms that have been destroyed
Research Initiative
the pathogen.
with chemicals, heat, or radiation. They are
Having healthy animals is the wish of every
How do vaccines work
the inactivated and attenuated vaccines.
deer farmer; however, it is hard work to keep animals healthy and requires a good herd
Vaccines expose the animal to parts of
Examples include IPV (polio vaccine), hepatitis A vaccine, rabies vaccine, and most influenza
health management plan. All animals have
pathogens, challenging the immune system to vaccines.
various defense mechanisms to prevent or deal with infections. These defense mechanisms of the animal can be directly influenced by age, nutrition, or inappropriate management practices. Stress due to heat, weaning, malnutrition, infection, transport, and other factors can impact how the immune system reacts to a pathogen attack.
react to a possible pathogen invasion. by creating memory cells for the antigens belonging to that specific pathogen. In the future, if the animal is exposed to the same pathogen, the immune system will quickly generate a response before the pathogen can cause disease. Each antibody is usually specific for only one antigen. Because of this, the immune system keeps a supply of millions of different antibodies on hand to be prepared to overcome any foreign invader. For a naïve animal, it may take 7 to 14 days after exposure to an infectious agent for the body to develop immunity to an antigen which is plenty of time for some pathogens to wreak havok on the body. On the other hand, it often takes only 48 hours to mount an immune response to the same antigen in a vaccinated animal.
An important component of any herd health plan is to have a vaccination protocol; yet, in the deer industry, there are few vaccines developed specifically for deer. Instead, vaccines developed for other species such as cattle, equine, sheep, or goats are used, if they have been labeled for use in deer. Still, few studies have measured efficacy of vaccines in deer; for most vaccines only anecdotal data are available. Most vaccines achieve protection, by priming the system to mount an antibody response. When an animal has not been exposed to a specific pathogen or comes in contact for the first time, it can be slow to develop antibodies. Most vaccines work by introducing the body’s system to proteins that are pathogen specific. Often, without this “sneak preview” of the vaccine, the animal cannot generate an immune response quick enough to clear or destroy the pathogen, making the animal susceptible to the agent and becoming sick. However, if the animal has a robust immune system or has been vaccinated, it will suppress the pathogen and, in time, clear or significantly reduce the infection. When an animal recovers from disease (or has been vaccinate), specific cells from the immune system will acquire the ability to remember and recognize the pathogens (virus, bacteria, toxin, or parasite) or parts of
24 SETDA 2021
may not be safe for use in
considered an intermediate phase between
There are several types of vaccines used in humans and animals. The majority of the licensed veterinary vaccines currently in use are inactivated (killed) vaccines, liveattenuated vaccines, or toxoids. All these represent different strategies used to reduce the risk of illness while retaining the ability to induce a beneficial immune response. Types of vaccines Attenuated vaccine: Some vaccines contain live, attenuated microorganisms. Many of these are active viruses cultivated under conditions that disable their virulent properties or use closely related but less dangerous organisms to produce a broad immune response. Although most attenuated vaccines are viral, some are bacterial. Attenuated vaccines have some advantages and disadvantages. Attenuated, or live, weakened, vaccines typically provoke more durable immunological responses. But they
Toxoid vaccine: Toxoids are made from inactivated toxic compounds produced by microorganisms that when activated cause damage to cells. Examples of toxoid-based vaccines include tetanus and clostridium. Not all toxoids are for toxins created by microorganisms; for example, Crotalus atrox toxoid is used to vaccinate dogs against rattlesnake bites. Subunit vaccines: These vaccines contain short, specific proteins that are the same as the antigens of the target pathogen. Rather than introducing an inactivated or attenuated microorganism to an immune system, a subunit vaccine uses a fragment to create an immune response. Conjugate vaccine: Certain bacteria have a polysaccharide outer coat, which is a weak antigen. By linking these outer coats to proteins (toxins), which are strong antigens, the immune system has a more robust response. Outer membrane vesicles (OMVs): OMVs are released spontaneously during growth by many groups of bacteria. They have the ability to naturally provoke an immune response in the body of a human or other animal and can be manipulated to produce potent vaccines. The best known OMVs vaccines are those developed for serotype B Meningococcal disease. Heterologous vaccines: Also known as “Jennerian vaccines,” are vaccines that are pathogens of other animals that either do not cause disease or cause mild illness in the organism being treated. The classic example is Jenner’s use of cowpox to protect against smallpox. A current example is using the