Porcine Viral Diarrhea

Viral diarrhea in pigs can be regarded as the number one disease that causes the death of piglets during lactation. Its infection is closely related to the age of piglets, especially epidemic diarrhea. The younger the piglet, the infection and disease And the more serious the death. The reason why suckling piglets are susceptible to viral diarrhea and most likely to cause piglet death is mostly because the viral diarrhea virus damages the intestinal villi of piglets very seriously. The most serious epidemic diarrhea can cause 100% shedding of intestinal villi of suckling piglets. Transmissible gastroenteritis can cause over 60% shedding of intestinal villi of suckling piglets. Even rotavirus, which is not very serious, can fall off. This results in the shedding of about 50% of the intestinal villi of suckling piglets. However, the regeneration ability of intestinal epithelial cells of piglets is very limited, and the recovery of intestinal villi is very slow. It takes 8 days for piglets to renew intestinal villi at 1 day, and 4 days for piglets at 14 days of age.

Therefore, inducing intestinal mucosal immunity to protect intestinal epithelial cells is the focus of preventing these viral diarrhea diseases. However, the immune system of piglets is not fully developed, and direct vaccination of diarrhea vaccine cannot induce effective humoral immunity or intestinal mucosal immunity to achieve protection. Therefore, maternal antibodies are the most important way to protect piglets from PEDV.
There are two types of maternal antibodies in sow milk: single-chain antibodies and double-chain antibodies. Single-chain antibodies are what we often call IgA, IgG, IgM, etc., and double-chain antibodies are sIgA.

The single-chain antibody in colostrum can only be transported through small intestinal epithelial cells within 24 to 48 hours after the piglet is born. With the formation of the sow’s blood-milk barrier, the colostrum will Transition to the milk stage, sIgA, which plays a leading role, persists in milk through lactation. Therefore, the IgG antibody obtained from sow colostrum is mainly used to prevent systemic infection of piglets, while the persistent sIgA antibody in milk provides piglets with specific passive immune protection against enterovirus infection. sIgA is resistant to proteases due to its special J chain structure, thus ensuring its high stability in the gastrointestinal tract. The sIgA antibody can inhibit viral cell penetration and infection, and play an important role in passive protection such as milk immunity and viral diarrhea in newborn piglets. And sIgA is not only the main immunoglobulin in milk, but also the most important immunoglobulin in the mucosal surface and mucosal secretions.                                                       
Therefore, a sufficient amount of sIgA in the intestinal lumen of newborn piglets is very important to prevent infections such as viral diarrhea virus.
And if you want to produce enough sIgA, you need to use the sow's intestine-mammary gland-sIgA axis.
In 1972, Bohl et al. discovered the "gut-mammary gland-sIgA axis" in pigs (IgA immune effector cells shuttle from the intestine to the mammary gland). Studies have shown that the milk of sows that have undergone natural infection or oral inoculation of viral diarrhea virus and recovered sows contains persistently high levels of sIgA antibodies, which can protect piglets from viral diarrhea.
Passive immunity through the "gut-mammary gland-sIgA axis" is an effective way to protect piglets against viral diarrhea. The main antibody secreted by the intestine is sIgA, which is formed by the migration of dimeric IgA secreted by intestinal plasma cells to the intestinal lumen. Therefore, the induction of mucosal immunity in pregnant sows is the basis of milk immunity. The antibody-secreting cells/plasmoblasts of mucosal immunity must migrate to the mammary gland through the "gut-mammary gland-sIgA axis", and finally provide passive immune protection for piglets through mammary gland secretions. . Therefore, we say that "milk immunization" is the most effective way to prevent and control piglet viral diarrhea.
How to improve the sow's "milk immunity" ability?
Weidao No. 1 is a mucosal immune micro-ecological product for diarrhea. It contains immune micro-ecology, which can stimulate the intestines of sows and piglets to produce sIgA against viral diarrhea. The sIgA is continuously produced by sows’ milk immunity. Supply piglets so that their intestines are protected by sIgA, thereby reducing the intestinal damage of suckling piglets caused by viral diarrhea, and effectively reducing the occurrence and death of suckling piglets!