How long will it be before Chinese manufacturers commercialized THE vaccine against African swine fever?
Since last year, the outbreak of African swine fever has led to a decrease in domestic pig stocks and a rise in pig prices. Therefore, the research and development of a vaccine against African swine fever has become a top priority.
China's research and development of a vaccine against African swine fever (ASF) made significant progress in August this year after laboratory research in April, the Chinese Academy of Agricultural Sciences (CAAS) said Thursday. A live attenuated vaccine with double gene deletion has completed the laboratory safety assessment and effective experiment, which has broken the bottleneck of large-scale production technology. Recently, an application for biosafety assessment has been submitted to the Ministry of Agriculture and Rural Affairs, and it is about to enter the clinical trial stage.
China may soon be the first country to develop a vaccine for African swine fever, which has not been developed for a century. However, more clinical data are needed to see if the vaccine can change the evolution of CSFV.
A paper patent becomes the pig's expectation
African swine fever is a deadly disease for pigs. After the virus infected pigs, can lead to acute, hemorrhagic fever (40 ~ 42 ℃), heart rate, breathing difficulties and other symptoms, some accompanied by cough, eyes, nose has purulent secretion of serous or mucus sex, skin cyanosis, lymph nodes, kidney, gastrointestinal mucosa bleeding and other symptoms obviously, the onset process short, acute infection mortality rates as high as 100%, belong to the deadly infectious diseases, by the world organization for animal health (OIE) as a statutory reporting animal epidemics, also is our country key prevention of animal epidemics.
The best way to bring the epidemic under control is to find a vaccine.
On August 6, 2019, a patent was published on the Website of the State Intellectual Property Office of the People's Republic of China for an invention entitled "Gene-deficient attenuated African swine fever virus and its Application as a vaccine". Inventors: Bu Zhigao, Chen Weiye, Zhao Dongming, He Xijun, Liu Renqiang, Liu Jinxiong.
The announcement said that the two African swine fever (ASF) gene-deficient viruses developed by the Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences (CAS) were both able to provide 100 percent immune protection against the virulent strains of ASF circulating in China, and could be used as safe and effective vaccines for the prevention and control of ASF.
This invention adopts the epidemic strain of African swine fever (ASF) in China, Pig/CN/HLJ/2018. After genetic engineering technology, the virulence genes of ASF virus are deleted, and mgF360-505R deletion and CD2V combined with MGF360-505R deletion virus are obtained. The experimental results show that both strains can provide 100% immune protection against African swine fever (ASF), which can be used as a safe and effective vaccine for the prevention and control of ASF epidemic in China, and have great social value.
HLJ/18 wild virus, the "epidemic strain" used in the development of a vaccine against African swine fever, was the first strain isolated in the research. On March 23 this year, the Harbin Animal Research team released information that the above virus is the first successful isolation of samples from the Jiamusi epidemic in Heilongjiang province. The biological characteristics of this strain, such as infectivity, virulence and infectivity, were systematically studied, and the animal infection model was successfully established, which was the first step in the research and development of African swine fever vaccine.
Bu Zhigao, director of the Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, presented the research results at the 18th National Academic Seminar of the Sub-society of Animal Infectious Diseases of the Chinese Society of Animal Husbandry and Veterinary Sciences held from August 16 to 19.
Bu Zhigao, director of the Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, presented the research results at the 18th National Academic Seminar of the Sub-society of Animal Infectious Diseases of the Chinese Society of Animal Husbandry and Veterinary Sciences held from August 16 to 19.
According to step chigo, accurate knock out virulence genes, especially against the host immune, innate immune regulation genes, and thus obtain the attenuated live attenuated, double lack of security of veterinary vaccine should be request, not cause temperature and abnormal clinical and pathological damage, the replication level is extremely low, can quickly remove, does not have a target level between animal communication ability, the body can't successive batches, non-toxic strong force to return risk. Two key breakthroughs have been made in laboratory research. The safety of live vaccines for animal use has reached the required standards, the production technology of primary cells is feasible, the quality is controllable, and the conditions for industrial pilot test and clinical use have been met.
At present, the Harbin Veterinary Research Team has selected safe and effective candidate vaccine strains with double gene deletion, basically completed laboratory product quality research, and established product technology (manufacturing and inspection procedures) and quality standards. Safety evaluation of Gmos and trial production of preclinical pilot products are under way. Clinical trials and commercial marketing await.
At present, the Harbin Veterinary Research Team has selected safe and effective candidate vaccine strains with double gene deletion, basically completed laboratory product quality research, and established product technology (manufacturing and inspection procedures) and quality standards. Safety evaluation of Gmos and trial production of preclinical pilot products are under way. Clinical trials and commercial marketing await.
As early as last month, the vaccine had entered the pilot test stage, China Business News reported from sources with the Harbin Research Institute. Whether the patent will be a boon to China's pig industry, however, awaits the results of clinical trials.
The mutation of the virus is still unknown
To make a vaccine, you first need to know what the virus is.
"Foreign data show that there are 24 subtypes of African swine fever, but there is no data on which subtype is more prevalent and has a high mortality rate in pigs in China." An African swine fever virus researcher said that to understand the situation of African swine fever, there is a lot of work to be done. Laboratory testing is needed for African swine fever in all places. The basic work is done before screening out the most suitable strains for vaccine development. Otherwise, if there is no targeted vaccine, it may not provide much protection.
In fact, pigs do not only provide pork for human consumption, but also serve as a "mixing vessel" for a variety of viruses, which mix and mutate in pigs and then transmit the mutated virus to humans. This is because pigs have double-receptor properties that can infect both humans and birds. Like influenza viruses, pigs act as intermediate hosts for the spread of influenza viruses, giving them more opportunities to recombine. When pigs are simultaneously infected with swine influenza virus, avian influenza virus and other viruses from different sources, reassortative viruses may be produced, and the reassortative viruses are likely to acquire the ability to spread across species and produce highly pathogenic viruses that can cause outbreaks in humans.
So, as a rapidly mutating virus, what happened to AFRO in pigs? "We do not know this mutation at present. We lack the virus mutation after THE introduction of AFCD into China." The researchers said.
The lack of research on the situation of African swine fever virus also brings confusion to the birth of African swine fever vaccine.
One breeder, however, has low hopes for a vaccine, "because the virus is not well known, and if it is not circulating in pigs, it will not work. After all, there are 24 known strains of the virus, and there are many unknown and mutated viruses".
The road to development is not yet successful
For a hundred years, scientists around the world have failed to develop a vaccine for African swine fever.
"This virus does pose a big test for humans." As Buchko explained at the meeting, ASF virus cannot be adapted to be weakened by passage of other animals, and it only infects dead target animals such as pigs or wild pigs. Most virus strains only infect pig primary macrophages. And there are no alien host relatives to borrow from.
An animal husbandry expert also said that the African swine fever virus mutates very quickly, perhaps as soon as the vaccine is given, the virus in the body has changed, and even become more virulent, and the pig will die more quickly.
This mutation and adverse reactions caused the vaccine for African swine fever to go ahead for 100 years. For hundreds of years, scientists have tried inactivated vaccine, attenuated vaccine, subunit vaccine, DNA vaccine and genetic engineering vaccine, but no vaccine has been commercially available.
For example, at the end of 2018, Spanish scientists announced that they had developed a live attenuated vaccine with certain genes missing, which has a certain ability to prevent and control infection, but its effectiveness and safety still need to be improved. In October 2018, the United States awarded A patent to Pegaton (formerly Pfizer) for an African swine fever vaccine based on MFG gene deletion, but the likelihood of its widespread availability remains unknown.
None of these vaccines has reached the pilot stage, and China may become the first country to develop and commercialize a vaccine against African swine fever.
