Abstract: Classical swine fever (CSF), a list A disease of Office International des Epizooties, is caused by classical swine fever virus (CSFV) belonging to the Flaviviridae family. The well-known lapinized Chinese strain of CSFV, also known as C-strain, was developed in China in the middle 1950s. In the past half a century, the vaccine has been proved to be safe and immunogenic in pigs of essentially any age. It is of high efficacy. It provides immunized animals with broad-spectrum, sometimes lifelong, protection, which is contributed by cell-mediated immunity and humoral immunity, against essentially all genotypes or subgenotypes of the virus. The maternal antibodies derived from immunized sows can confer solid protection of their offspring from disease; however they have been proved to inhibit the successful immunization of C-vaccine. The complete genome of C-strain, together with those of its parent Shimen and dozens of established and field strains, has been sequenced and annotated. Recently, the reverse genetics system of C-strain has been developed, resulting in several C-strain-derived candidate marker vaccines. Many countries manage to control or even eradicate CSF with the aid of C-strain vaccination. In spite of these efforts, the eradication of the disease worldwide remains a big challenge and needs a long way to go, and provably still resort to genetically modified C-strain. This paper reviews the different aspects of the vaccine, which has stood the test of half a century.

Key words: Classical swine fever, Classical swine fever virus, C-strain vaccine