Encephalomyocarditis virus

Encephalomyocarditis Virus
Scientific classification
Family: Picornoviridae Genus: Cardiovirus

Description and Significance

Encephalomyocarditis Virus(EMCV) is a member of the genus Cardiovirus of the family Picornaviridae. The Pacornavirusinfects many animal species, including pigs, rodents, cattle, elephants, raccoons, marsupials, and primates such as baboons, monkeys, chimpanzees, as well as humans. There are two types of EMVC. One is Encephalomyocarditis Virus type A, which causes reproductive problems. The other one is Encephalomyocarditis Virus type B, which causes heart failure in pigs. African Elephants were the first species that were known to be infected with the virus. The first outbreak ever seen was in South Africa in 1993. Between December 1993 and August 1994, a number of acute deaths occurred in free-ranging Africa elephants in the Kruger National Park KNP. 4

Epizootiology

The main host of Encephalomyocarditis Virus(EMCV) are the rat and mouse. The virus is passed through fecal oral transmission. This discovery was documented after a large population explosion in rodents during the same time as a large of number of elephants where dying. Encephalomyocarditis Virus(EMCV) attacks many animals as mentioned previous but studies documenting pig infection seem most prevalent. This virus causes acute myocarditis and sudden death in preweaned pigs, whereas trans placental infections of sows cause fetal mummification, abortion, still birth,and neonatal death. 4 Once humans are infected with this virus, the symptoms they may be faced with include fever, neck stiffness, lethargy, delirium, headaches, and vomiting. In primates such as gibbons and owl monkeys, Encephalomyocarditis Virus can cause necrotizing and interstitial myocarditis.[6] Transmission and pathogenesis occurs by ; incubation from nine to ten days, oral, fecal and urine contamination of food, sub clinical infections, replication in myocardial and kills them.

Transmission and Pathogenesis

Some diagnoses may be antemortem due to rapid clinical course, gross lesions such as pale streak in the myocardium, hydrothorax, hydropericardium, pulmonary edema, froth in tracheobronchial tree. Other diagnoses are through histopathology showing myocardial degeneration and necrosis with lymphocytic infiltrates, virus particles may be visible on electron microscopy, definitive diagnosis: virus isolation, PCR, mouse inoculation, serological test for antibodies available-Texas A&m. 5 The only treatment I have read about actually a treatment, but prevention, the oil-adjuvant Encephalomyocarditis vaccine. This vaccine has been given to elephants, mice and pigs so far. Also, scientist are finding that controlling the rodent population is crucial to preventing the spread of this disease. Immune prophylaxis is considered to be another one of the effective strategies for controlling this virus in pigs and other animals who may possibly carry the virus. In humans it's very rare to get this virus.

Application to Biotechnology

There are many methods used to further study the effects of this virus. One was the viruse isolation and serology, which consisted on inoculation of a infected tissue of the bull elephant in the Kruger National Park (KNP)into mice. Vaccine seed virus was prepared by adapting this E1-M1 isolated by passing five time on a monolayer of BHK 21 clone 13 cells which are used at the laboratory for routine foot-and-mouth disease (FMD) vaccine production. 4 Seology is the virus neutralization test that is used as antigen. Another way is the oil adjuvant which is the double suspension which was used as vaccine for pigs, elephants, and mice. Virus titrtion is flat-bottomed micro titer plates using an in-house modification and tryptose, referred to as Vac medium, for the dilution of the virus and suspension of the BHK cells. The plates where incubated at 37 Celsius for forty-eight hours in humidified chamber containing five percent of carbon dioxide and the test read with an inverted microscope. The last one mentioned in the journal was virus isolation of samples which were processed by diluting blood, ground up tissue or fecal samples and titrating the sample on microtiter plates, using BHK cells as an indicator system. Then the blood samples were diluted one over ten in medium and then diluted as described for the tissue sample. They were examined daily for cyopathogenic effect for up to seven days. 4

The efficacy of an experimental oil-adjuvanted encephalomyocarditis vaccine in elephants, mice and pigs

The scientist in charge of preparing this vaccine found that there are many ways develop the vaccine that is most appropriate to control the virus. One of the ways of doing so was cultivation of the virus, a multiple process monolayers production system employing BHK 21 clone13 cells was used as described with the modification of freezing and defrosting the roller flask before harvesting to enhance the release of virus. 4 Eight elephants, ten mice, and four piglets were some of the animals used in an experiment to test the vaccine when it was introduced. The elephants were held in an isolation stable at Skukuza in the KNP. For vaccination and bleeding procedures the elephants were immobilized using a combination of carfentanil and azaperone or etorphine.4 The elephants were examined for clinical signs heart function was monitored by using an electrocardiogram. The antibody level of vaccinates and control was determined.

References

1 Aravindan, V., Vickraman, P. 2007. A novel gel electrolyte with lithium difluoro(oxalato) borate salt and Sb2O3 nanoparticles for lithium ion batteries. Solid State Sciences 9(11): 1069-1073

2Brewer, L.A., Lwamba, H.C.M., Murtaugh, M.P., Palamnberg, A.C., Brown, C., Njenga, M.K.2001. Porcine Encephalomyocarditis Virus Persists in Pig Myocardium and Infects Human Myocardial Cells. Journal of Virology 75(23):11621-11629

3[1] Gandolf, DVM A.R. 2003. Encephalomyocarditis Virus (EMCV):Options for Vaccation of Elephants. Retrieved 2009, from American Association of Zoo Veterinarians website:

4Hunter, P., Swanepoel, S.P., Esterhuysen,J.J., Raath,J.p., Bengis,R.G.,and Van Der Lugt,J.J.1998. The efficacy of an experimental oil-adjuvanted encephalomyocarditis vaccine in elephants, mice and pigs. Vaccine 16(1):55-61

5[2]Mikota, DVM Susan. Encephalomycarditis (EMC, EMCV). Retrieved 2009, from Elephant Care International Website:

6[3] Encephalomyocarditis (EMCV). Retrieved 2009, from Zoologix, Inc. Website:

7[4]Encephalomyocarditis virus type A, causes reproductive problems, type B causes heart failure in pigs. Retrieved 2009, from European Bioinformatics Institute website