New China swine fever strains point to unlicensed vaccines

BEIJING (Reuters) – A new form of African boar fever identified in Chinese pork farms is caused by illegal vaccines, industry insiders say, a fresh blow to the world’s largest pork producer, right now Is also recovering from a devastating epidemic of viruses.

FILE PHOTO: The pig was sighted on September 5, 2018 on the outskirts of Harbin, Heilongjiang Province, China. REUTERS / Hallie Gu

Two new strains of African swine fever have infected more than 1,000 bovines on several farms owned by China’s fourth-largest producer, New Hope Liouhe, as well as pigs being hunted for the firm by contracted farmers, the company. Chief Science Officer of Yan Yan Zichun said. .

Although one or two key genes present in the wild African boar fever virus are missing, but do not kill pigs like the disease that devastated China’s fields in 2018 and 2019, they cause a chronic condition that leads to a number of healthy pills. Reduces birth, Yan told Reuters. In New Hope and many large producers, the disease is effectively made fatal to prevent the spread of infected pigs.

Although known infections are now limited, if the strains spread widely, they can destroy pork production in the world’s top consumer and producer; Two years ago, half of China’s 400 million-head pig herds eliminated boar fever. Pork prices are still at record levels and China is under pressure to strengthen food security amid the COVID-19 epidemic.

“I don’t know where they come from, but we find some mild gene infections caused by some type of gene-deleted virus,” Yan said.

Wayne Johnson, a veterinarian in Beijing, said he diagnosed a chronic or less fatal form of the disease in pigs last year. The virus lacked some genetic components, known as the MGF360 gene. New Hope stated that viruses from both the MGF360 gene and the CD2v gene are missing.

Research has shown that deletion of some MGF360 genes from African swine fever builds immunity. But the modified virus was not developed into a vaccine because it later mutated back into a harmful state.

“You can sequence these things, these double deletions, and if it is exactly the same as described in the lab, then it is very coincidental, because you will never find this exact deletion,” International Scientist for Livestock Said Lucilla Steinna. Research Institute (ILRI) in Nairobi.

There is no approved vaccine for African boar fever, which is not harmful to humans. But many Chinese farmers struggling to protect their pigs have resorted to unused products, industry insiders and experts. They fear that the illegal vaccine has caused an accidental infection, which is now spreading.

New strains can be spread globally through contaminated meat, which is fed on kitchen waste. Viruses in some pork products are known to survive for months.

China’s Ministry of Agriculture and Rural Affairs did not respond to two requests for comment.

But it has issued at least three warnings against the use of unauthorized African swine fever vaccines, warning that they could have serious side effects and that producers and users could be charged with criminal offenses.

In August, the ministry said it would test pigs for various types of the virus so that the use of the illegal vaccine could be investigated nationwide.

Any strains with gene deletions may indicate that a vaccine was used, it said. No findings have been published so far on this issue, which is highly sensitive for Beijing. The recent reporting of African swine fever outbreaks was extensively covered. For link to the report, click here

Man-made strain

Decades later, researchers around the world are focusing on live-virus vaccines in the direction of produce a vaccine against the huge, complex swine fever virus – the only type to deliver on any promise.

But such vaccines carry a higher risk because even after the virus is weakened it does not cause serious illness, it can sometimes cure the virus.

One such vaccine, used in Spain in the 1960s, caused a chronic disease in pigs with inflamed joints, skin lesions, and respiratory problems, complicated efforts to eradicate African boar fever over the next three decades. . Since then, no nation has approved the vaccine for the disease.

It is being tested by the Harbin Veterinary Research Institute of China after promising to remove a vaccine with the MGF360 and CD2V genes.

Yan said he believes that people have repeated scenes of strains of the virus being studied, which have been published in scientific literature, and that pigs have been subjected to illegal vaccines based on them, which others Can infect.

“It is definitely man-made; It is not a natural stress, ”he said.

Neither Johnson nor Yan have fully sequenced the new swine fever strains. Beijing strictly controls who is allowed to work with the virus, which can only be controlled in laboratories with high biodiversity designations.

But many private companies have developed test kits that can test specific genes.

GM Biotech, based in China’s central Hunan province, said in an online post last week that it had developed a test to determine whether the pathogen is a virulent strain, a single gene deleted strain, or a dual gene deleted attenuation strain .

The company said it helps pig producers because the new stages are “very difficult to detect in the early stage of infection and have a longer incubation period after infection,” the company said.

The government has not revealed how many illegally used vaccines are or who have produced them. But a “vast amount” of pigs have been non-vaccinated in China, Johnson said, a sentiment sent by many other experts.

In 2004–5, when H5 bird flu strains were spreading throughout Asia, Chinese laboratories produced several unauthorized live bird flu vaccines, said Mo Salman, a professor of veterinary medicine at Colorado State University, who worked on animal health in Asia Have done There are fears that they may produce dangerous new variants.

“The current ASF in China is repeating history to the illegal vaccine (s),” said Salman.

Reporting by Dominic Patton. Editing by Gerry Doyle


Leave a Reply

Your email address will not be published.