Using designer egg immunoglobulins against PEDV

Since May 2013, the U.S. pig industry has been battling Porcine Epidemic Diarrhea Virus (PEDV) outbreaks. PEDV, a highly contagious disease, has already spread to at least 14 states. PEDV is a member of the Coronaviridae family that also includes other swine viruses such as Transmissible Gastroenteritis (TGE), Porcine Respiratory Coronavirus (PRCV), and Porcine Haemagglutinating Encephalomyelitis Virus (HEV).

Duration of diarrhea decreased from 6.5 days in the control group to 1.3 days in the trial group with the highest antibody dose.
Duration of diarrhea decreased from 6.5 days in the control group to 1.3 days in the trial group with the highest antibody dose.

Since May 2013, the U.S. pig industry has been battling Porcine Epidemic Diarrhea Virus (PEDV) outbreaks. PEDV, a highly contagious disease, has already spread to at least 14 states. 

PEDV is a member of the Coronaviridae family that also includes other swine viruses such as Transmissible Gastroenteritis (TGE), Porcine Respiratory Coronavirus (PRCV), and Porcine Haemagglutinating Encephalomyelitis Virus (HEV). 

After an incubation time of 22 to 36 hours, severe symptoms as diarrhea and vomiting can occur and infect up to 100 percent of a pig herd. Suckling piglets younger than seven days are the most sensitive group with mortality rates of 80 - 100 percent. The transmission is faecal-oral, no vector or reservoir has been implicated in its spread (1). The consequences of this disease are losses of animals, decreased performance and increased costs for medical treatment and biosecurity measures.

Antibiotics are not effective against viruses; preventive measures like vaccination and biosecurity in addition to a well-organized colostrum management are generally applied. In case of disease, there is the possibility of supportive therapy against dehydration by administering electrolyte solutions.

Designer egg IgY

Over numerous generations, farmers have fed eggs to weak or ill calves and piglets. Why? In 1893, Veterinarian, Felix Klemperer (2), provided the explanation on how this treatment supports an animal's immune system. He discovered that eggs from hens vaccinated with tetanus bacilli helped mice survive tetanus. This meant that hens naturally produce antibodies against this disease, and they transfer those into the egg.

As traditionally kept farm hens "lived" in close proximity with manure from all animals, they came in contact with all farm pathogens. They did not get ill, but instead, the hens produced antibodies against these different diseases. Of course, if hens get in contact with PEDV they also build up antibodies against this disease. 

If immunoglobulins from the egg (IgY) are used as a natural ingredient for feed supplements, they act mainly in the gut. They bind to surface molecules of the pathogens, and can block their binding sites to the intestinal wall and prevent host colonization. In other words, IgY have the potential of preventing PEDV from causing damage to a pig.

PEDV research results

Kweon et al. (3) in 2000 showed good results with feeding IgY to piglets without earlier contact to PEDV. They challenged them with different dosages of PEDV. All piglets (n=36) showed clinical signs, but in the test group 17 of 19 piglets survived, whereas in the control group nine of 17 died. When IgY was applied to piglets on farms dealing with PEDV the survival rate was two-fold higher!

Another trial conducted in Japan, in the same year by Ohsugi, M. et al. (4), used 16 one-day-old suckling piglets randomly divided into four groups; one control and three test groups. All groups were challenged with an infective dose of a PEDV strain at three days of age. The three test groups additionally received PEDV-specific egg yolk antibodies at different concentrations 30 minutes after the challenge. The results are shown in Figures 1 - 3.

Duration of diarrhea decreased from 6.5 days in the control group to 1.3 days in the trial group with the highest antibody dose. Also, body weight gain showed an indirect correlation to the antibody dose. 

The piglets of the control group, on average lost 18.5 percent of their body weight, the second group with the AB titre of 1/64 lost only 7.9 percent and the other two groups with titres of 1/128 and 1/256 had 3.9 and 7.8 percent weight gain, respectively. Concerning mortality, even the lowest dose applied showed an increase in survival rate up to 75 percent, whereas the two- and four-fold dose provoked a reduction of mortality to 0 percent.

References:

1. USDA (2013): Porcine Epidemic Diarrhea (PED); Technical Note

2. Klemperer, F. (1893): Ueber natürliche Immunität und ihre Verwerthung für die Immunisierungstherapie. Archiv für Exper. Pathol. Pharmakol. 31: 356-382.

3. Kweon, C., Kwon, B., Woo, S., Kim, J., Woo, G., Son, D., Hur, W. and Lee, Y. (2000): Immunoprophylactic Effect of chicken egg yolk immunoglobulin (IgY) against porcine epidemic diarrhea virus (PEDV) in piglets. J. Vet. Med. Sci. 62(9): 961-964.

4. Ohsugi, M; Ikemori, Y.; Umeda, K.; Yokoyama, H.; Kobayashi, Y.; Hashi, T.; Kuroki, M.; Faustino, C,; Icatlo, Jr.; Nguyen, Sa V. and Kodama, Y. (2000): Efficacy of porcine epidemic diarrhea virus (PEDV)-specific chicken egg yolk antibody for oral passive immunization against experimental infection in newborn piglets. GHEN Corporation, Immunology Research Institute Gifu; unpublished data.

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