Transmissible Gastroenteritis Virus

Transmissible gastroenteritis is a highly contagious disease of swine. Incidence of the disease is highest in winter and early spring. It is caused by transmissible gastroenteritis virus (TGEV), a single-stranded RNA (ssRNA) coronavirus with an immunodominant spike (S) glycoprotein. The S protein induces neutralizing antibodies against the virus, and protective immunity is directed toward this protein. Transmission is by oral exposure to contaminated feces. Birds and insects may transmit the virus to susceptible herds. The virus remains infective in frozen, contaminated carcasses. Because of the rapid course of the disease and the immaturity of their immune system, newborn piglets are unable to develop their own protective immunity and depend upon the presence of S-IgA in mother's milk for protection against the virus.2,3 Conventional vaccines

Clinical signs are most severe in young piglets, and include vomiting, profuse watery yellow diarrhea, rapid weight loss and dehydration. Death may result within one week of onset of clinical signs. High mortality rate (up to 100%) is seen in piglets under two weeks of age. Infections of adult swine are asymptomatic. However, exceptions occur, where even adult pigs have vomiting, diarrhea, fever, loss of appetite, and die. Vaccination of boars, gilts, and sows moderately reduces the signs1,4



There is no specific treatment for piglets infected with TGEV. Supportive therapy includes fluids containing glucose and electrolytes. Antibiotics may protect against bacterial infections. 4

In one study performed at College of Veterinary Medicine and Bio-Safety Research Institute, Chonbuk National University, Jeonju, Republic of Korea, the enhanced protection against the TGEV was demonstrated in 2011. A preparation of swine interferon-α (swIFN-α) and interleukin-18 (swIL-18) was administered to piglets using attenuated Salmonella enterica serovar Typhimurium as carrier of cytokine proteins. A single oral co-administration of the preparation induced enhanced alleviation of the severity of diarrhea caused by TGEV infection, compared to piglets administered Salmonella enterica serovar Typhimurium expressing swIFN-α or swIL-18 alone. This enhancement was further observed by the reduction of TGEV shedding and replication. 5

References

  1. Nigel James Maclachlan, Edward J. Dubovi. Fenner's Veterinary Virology
  2. David G. Baker. Natural Pathogens of Laboratory Animals: Their Effects on Research
  3. John Bienenstock, Jiri Mestecky, Michael E. Lamm, Jerry R. McGhee, Warren Strober. Mucosal Immunology
  4. James G. Fox. Laboratory Animal Medicine
  5. Enhanced protection against infection with transmissible gastroenteritis virus in piglets by oral co-administration of live attenuated Salmonella enterica serovar Typhimurium expressing swine interferon-α and interleukin-18. Lee BM, Han YW, Kim SB, Rahman MM, Uyangaa E, Kim JH, Roh YS, Kim B, Han SB, Hong JT, Kim K, Eo SK.





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