Swine flu (swine influenza) is a respiratory disease caused by viruses (influenza viruses) that infect the respiratory tract of pigs, resulting in nasal secretions, a barking cough, decreased appetite, and listless behavior. Swine flu produces most of the same symptoms in pigs as human flu produces in people. Swine flu can last about one to two weeks in pigs that survive. Swine influenza virus was first isolated from pigs in 1930 in the U.S. and has been recognized by pork producers and veterinarians to cause infections in pigs worldwide. In a number of instances, people have developed the swine flu infection when they are closely associated with pigs (for example, farmers, pork processors), and likewise, pig populations have occasionally been infected with the human flu infection. In most instances, the cross-species infections (swine-origin virus to man; human flu virus to pigs) have remained in local areas and have not caused national or worldwide infections in either pigs or humans
Influenza A viruses cause acute respiratory infections in swine that result in significant economic losses for global pig production. Currently, three different subtypes of influenza A viruses of swine (IAV-S) co-circulate worldwide: H1N1, H3N2, and H1N2. However, the origin, genetic background and antigenic properties of those IAV-S vary considerably from region to region. Pigs could also have a role in the adaptation of avian influenza A viruses to humans and other mammalian hosts, either as intermediate hosts in which avian influenza viruses may adapt to humans, or as a “mixing vessel” in which influenza viruses from various origins may reassort, generating novel progeny viruses capable of replicating and spreading among humans.
These potential roles highlight the importance of controlling influenza A viruses in pigs. Vaccination is currently the main tool to control IAV-S. Vaccines containing whole inactivated virus (WIV) with adjuvant have been traditionally used to generate highly specific antibodies against hemagglutinin (HA), the main antigenic protein. WIV vaccines are safe and protect against antigenically identical or very similar strains in the absence of maternally derived antibodies (MDAs). Yet, their efficacy is reduced against heterologous strains, or in presence of MDAs. Moreover, vaccine-associated enhanced respiratory disease (VAERD) has been described in pigs vaccinated with WIV vaccines and challenged with heterologous strains in the US. This, together with the increasingly complex epidemiology of SIVs, illustrates the need to explore new vaccination technologies and strategies. Currently, there are two different non-inactivated vaccines commercialized for swine in the US: an RNA vector vaccine expressing the HA of a H3N2 cluster IV, and a bivalent modified live vaccine (MLV) containing H1N2 γ-clade and H3N2 cluster IV.
Benefits of Swine Influenza Vaccine For Pigs
A. Flu vaccines for pigs can help, but are not 100% effective. Sometimes the vaccine used may not protect against the virus or viruses circulating. In addition, current vaccines may not be effective in young pigs due to interference from antibodies received from the sow. Generally, protection of young pigs is achieved by vaccinating sows; however, those maternal antibodies are not fully protective for the young pig and decrease by the time they are 10 to 13 weeks old or sooner. Producers may vaccinate their animals after maternal antibodies decrease.
Features of Swine Influenza Vaccine For Pigs
- Influenza A virus causes a highly contagious respiratory disease in a variety of hosts, transferring from humans to pigs and pigs to humans.
- The primary means for controlling influenza disease are reducing the incidence of flu transmission, vaccination and best management biosecurity practices.
- Effective and beneficial vaccines provide both excellent adjuvants (carriers) and updated strains of influenza virus.
- Timing of vaccination is fundamental to efficacy. In most instances, booster vaccination programmes which are beyond three weeks from the primary dose, will be efficacious.
- Vaccination failure is Nature’s way of telling us that our protocols are not optimal for the best immune response for the pig.
Prices of Swine Influenza Vaccine For Pigs