Pigs to be culled at a farm infected with African swine fever in Paju, a South Korean city near the country’s border with North Korea.Credit: Yelim LEE/AFP/Getty

South Korea has mobilized military snipers and drones along the demilitarized zone between itself and North Korea to stave off wild boars carrying African swine fever. The country is the latest to report cases of the highly contagious and lethal virus in pigs, which has wiped out tens of millions of the animals across Asia.

The South Korean outbreak comes as Chinese scientists report in Science on 17 October1 that they have obtained the most detailed picture yet of the virus’s structure, which could assist vaccine development. There is currently no vaccine or treatment for African swine fever, which is contained by culling pigs.

Cases of African swine fever began appearing in South Korea in wild boars and pigs on farms near the North Korean border last month. Authorities there have confirmed fifteen cases in wild boars and fourteen in domestic pigs. The nation has culled more than 150,000 pigs since then, says the agriculture ministry.

The defence ministry announced on 15 October that it has mobilized snipers and civilian teams of hunters to take down wild boars near the border with North Korea, according to the South Korean media. Drones with thermal vision have also been used to track boars, reported the South Korean agricultural ministry.

The Food and Agriculture Organization (FAO) of the United Nations reported that as of 24 October, 10 countries in Asia have ongoing African swine fever outbreaks. China, which recorded its first case in August last year, has culled at least 1.9 million pigs because of the virus, according to the FAO.

Detailed structure

To look at the African swine fever virus structure, the researchers in China used a technique called cryo-electron microscopy, in which samples are suspended in ice at cryogenic temperatures. The team analysed images of more than 43,000 virus particles using computer algorithms, which improved the resolution over existing data by a factor of two. This allowed the team to reconstruct a model of the virus’s protective shell, which consists of 17,280 proteins, and the intricate patterns they form as the shell assembles itself.

Linda Dixon, a virologist at The Pirbright Institute in Woking, U K, says the lack of knowledge about the virus’s molecular structure has hindered researchers’ understanding of how the virus enters host cells. The Science paper, and another study published this month2, provide the first detailed architecture of the virus particle, says Dixon, and reveal several previously unknown and unique features. Understanding how the virus enters a cell might help researchers to identify receptors that could be used to block its entry, she says.

The work should aid vaccine development, Bu Zhigao, director of the Harbin Veterinary Research Institute and an author on the paper, told Chinese state media, China Daily. The institute has two vaccines under development.