Rinderpest is an acute subacute infectious disease that mainly infects ruminants, especially cattle. It is characterized by severe hemorrhagic catarrh in the mucosa, accompanied by necrotizing stomatitis and gastroenteritis, with low congenital resistance. The mortality rate of animals is high. Rinderpest originated in Asia and was introduced into Europe, causing serious losses. At present, rinderpest has been eliminated in Europe and the United States, and China has declared it out as early as the 1950s. However, the disease is still prevalent in Equatorial Africa and Northeast Africa. And this disease is also widespread in Afghanistan, Pakistan, Southeast Asia and other places bordering China.
- Physicochemical properties
The rinderpest virus is considered to be weakly resistant to physical and chemical factors. At 37 °C, the half-life of bovine prion infectivity in cell culture is 1 to 3 hours, and only 1 minute at 56 °C. However, a small number of viruses survived at 56 ° C for 60 minutes or 60 ° C for 30 minutes. After several months of storage at 4 °C , the infectivity decreased significantly. At -70 ° C for one year, the infection titer decreased. The virus is preferably stored lyophilized or stored at 2 ° C or less after addition of 2% dimethyl sulfoxide (DMSO). The inactivation of ultraviolet radiation is fast. Different strains have different pH stability, but most are inactivated at pH 4.0 or lower. The most stable pH is 7.2 to 8.0. The virus was inactivated by placing it in 20% diethyl ether chloroform at 4 ° C overnight. A prominent feature of the rinderpest virus is its very fragile glycerol, a phenomenon that has been used in the preparation of inactivated vaccines. Corruption can quickly inactivate the virus, and it may lose its infection when exposed to sunlight or naturally dry. The virus survives for a short period of time in the carcass, and the virus in the lymph nodes and spleen can survive for several weeks when stored at -25 °C. Strong base disinfection is best, glycerin, phenol, formaldehyde or β-propiolactone can quickly destroy the infectivity of rinderpest virus without significantly affecting its antigenicity.
- Blood coagulation
The rinderpest virus has not been proven to have hemagglutination activity, but the rinderpest virus antiserum inhibits the hemagglutinin of the measles virus. The rinderpest virus also functions as a measles virus hemagglutinin receptor site that blocks the surface of the monkey red blood cells. Treating the measles virus with ether and Tween-80 can break the viral envelope into small, uniform hemagglutinin particles. This agglutination of hemagglutinin particles to monkey red blood cells can be inhibited by high titers of canine distemper or rinderpest antibodies. HeLa cells infected with measles or canine distemper virus can adsorb red blood cells of guinea pigs, but rinderpest virus cannot adsorb red blood cells.
The antigenicity of all strains of the rinderpest virus is the same. Serological studies have shown that virions contain many soluble antigens that are not related to infectivity, including complement-binding antigens. This complement-binding antigen can be extracted from infected tissues with alcohol, acetone, or ether, and it can resist boiling for 20 minutes. There are also some precipitated antigens, two of which are thermostable; the third antigen moves the slowest during electrophoresis and is sensitive to heat. Precipitates are easily detected by using a suspension of acute diseased bovine lymph nodes and other tissues, or concentrated infected cell culture medium, and an anti-serum agar diffusion test. However, complement-binding antigens and precipitated antigens can be rapidly destroyed by spoilage. Triplex viruses are very antigenic, but each has a specific component, as evidenced by many serum tests. Cross-protection tests have shown that the immunity produced by canines infected with measles virus or rinderpest virus can resist the attack of canine distemper virus, but cattle cannot resist calves after vaccination with canine distemper virus. The hemagglutinin of the measles virus can be used as a reliable diagnostic method for detecting antibodies to calves and canine distemper.
There is an infectious disease similar to rinderpest in sheep and goats in West Africa, but not transmitted to cattle. The cytopathic effect of this virus in sheep kidney cell culture is similar to that of rinderpest virus. Adapted to cell proliferation, this virus can be used to immunize cattle against rinderpest. Conversely, rinderpest antiserum can also make sheep resistant to this virus. Therefore, the pathogen of sheep disease in West Africa may be a strain of rinderpest virus, which has lost the ability to infect cattle through natural pathways, but is easily transmitted in sheep.
To be continued in Part Two…