2. Experimental parasitology stage: On the basis of animal classification research since 1960s, experimental parasitology has gradually emerged. At the beginning, the life history of parasites was clarified by artificial infection and other experimental methods, as the basis for prevention and treatment, and its representative research was Jiang's experimental study on pig kidney disease. Later, there was artificial culture and even physiological and biochemical research. The content of experimental parasitology is very rich, and many technologies and disciplines are infiltrated into it, such as slicing technology, electron microscope technology, biochemical technology, cell culture technology, ecology, pharmacy, histology, pathology and so on. After the Cultural Revolution, with the support of the Ministry of Agriculture, a series of training courses hosted by Confucius of Beijing Agricultural University promoted the development of this stage.
3. Immunoparasitology and Biochemical-Molecular Parasitology: Immunoparasitology and Molecular Parasitology were born by applying the theory and technology of molecular biology. Immunity of parasites is a complex and difficult problem. This is mainly because,
First, the vast majority of parasites cannot be cultured without their hosts under artificial conditions;
Second, the development of parasites often has obvious stages;
Third, except protozoa, other parasites are multicellular animals with complex structures. All these bring many difficulties to extract and purify antigens that can stimulate animal immune response, which makes the development of immune parasitology falter.
Artificial culture of parasites has been explored and tried in many aspects. The artificial culture of protozoa, Giardia parasitized in digestive tract and Trichomonas parasitized in reproductive tract is quite successful. Some species of coccidia have been subcultured in chicken embryos and/or cell lines. The artificial culture of blood protozoa, such as pear-shaped worms and trypanosoma, has also made some progress, and the number of generations and numbers in the culture medium has increased obviously. Theileria annulata merozoite parasitized in bovine lymphocytes has been preserved in artificial culture medium for 10 years. It is difficult to cultivate worms artificially. The artificial culture of nematodes was carried out earlier, and the initial goal was to preserve their vitality and prolong their life as much as possible. Later, with the progress of science and technology, scientists gradually turned to artificial conditions to replace their whole life history. In this attempt, Angiostrongylus cantonensis without intermediate host was chosen as the research object. After more than 30 years' research, more than 10 species of Angiostrongylus cantonensis parasitic on ruminants and pigs have completed their whole life cycle in artificial culture system, and some species can not only develop to sexual maturity, but also lay eggs. For nematodes with intermediate hosts and all trematodes and tapeworms, people can only simulate a certain stage in their life history (in the final host or in the intermediate host) to create culture conditions, and there are also some successful cases. For insects and mites, their tissue cells (such as salivary gland cells) are generally used for culture.
The preparation of vaccine is generally to select a certain developmental stage of worms-usually the stage of invading the host, such as sporozoites of Haemophilus and coccidia, cercariae of Schistosoma japonicum, and the third stage larvae of nettail nematodes. So as to treat it weakly, infect the host with attenuated worms (antigens) and induce immunity. Weakening methods are physical, such as X-rays or γ-rays irradiating insects to weaken them, which are the two most commonly used methods; Chemical, some are controlled by chemical drugs after being inoculated with "virulent virus". For example, some researchers control cattle by injecting Benyr after inoculation with Trypanosoma brucei. Later, the virus attack proved that the vaccinated cattle gained some immunity; Biological, for example, some species of coccidia are weakened by the passage of chicken embryos and the cultivation of early-maturing and attenuated insect strains, and Babesia bovis is is weakened by the continuous spread in splenectomy calves.
There are also many attempts to make vaccines with subcellular components or cell-free soluble antigens. There are anti-idiotypic antibody vaccines and genetic engineering vaccines in modern times, mainly in trypanosoma, coccidia and schistosomiasis.
Because of the complexity of parasite life history and its antigen variation, it brings many difficulties to the study of parasite immunity. Vaccine production technology is still in the embryonic state, and fully finalized commercial vaccines are rare. As far as the effect of vaccine is concerned, its function is usually incomplete and it is a non-scavenging immunity.
Immunodiagnostic techniques such as immunofluorescence, immunoenzyme and monoclonal antibody have been widely used in the diagnosis and epidemiological investigation of parasitic diseases. Counting probes and polymerase chain reaction (PCR) technology have also been applied to the pathogen diagnosis and identification of some protozoa.
The research results of parasite physiology and biochemistry make the research and development of antiparasitic drugs get rid of the "chance" screening method in the past. Scientists can choose or synthesize a drug purposefully from how to block the nutrient metabolism or nerve conduction mechanism of parasites, which greatly speeds up the research and development of new drugs. 1. Scientific research: For quite some time after liberation, parasitologists have done a lot of work on the classification and fauna of parasites, which is an important and indispensable academic research and occupies an important chapter in the epidemiology of domestic animals in China. According to rough statistics, 209 species of trematodes belonging to 58 genera of 20 families were found in the multi-generation trematode table of Trematoda. There are 80 species of rotifers belonging to 34 genera in 6 families, and 3 species of Ye Jia order 1 family in Taenia. Linear nematodes, 7 orders, 2 1 family, 93 genera, 285 species; Spine head 2 orders, 3 families, 3 genera and 4 species; Protozoa flagellates 10 family 14 genus 15 species, pyriformis 2 families 2 genera 15 species, ciliates 1 order 1 family 1 species; Arthropoda, Acari, Acari, 8 families, 18 genera, 8 1 species, Insecta, 4 orders, 17 families, 39 genera, 1kloc-0/ 5 species, Pentagonal order,/. There are 909 kinds of parasites. Among them, nearly 100 is a new species found in China.
In the 1920s, Xiong Da-shi's research on horse colon and rumen ciliates of cattle and sheep was at the forefront of similar research in the world at that time, and Professor Xiong Da-shi was one of the pioneers in this field.
In 1960s, Kong et al.' s research on the geographical distribution and generalized Polygonum classification of Ascaris in Equidae in China was widely recognized internationally. Lichtenfels, in his book Worm -mesticEquids, thinks that this research is another milestone achievement after Ihle in the Netherlands, Erschow in the former Soviet Union and MeIntosh in the United States. On this basis, the artificial culture of Angiostrongylus cantonensis was studied.
In the study of trichinosis, Northeast Agricultural University cooperated with the Department of Medicine to establish insect species from the genetic level; Lanzhou Veterinary Research Institute has also made some achievements in vaccine and immunization research. The former PLA Veterinary University has done detailed research work on horse and sheep encephalomyelitis.
In the research of trematology, Xu Maotai and his colleagues from Shanghai Institute of Livestock Parasitology have made practical achievements in the epidemiology, vaccine development and comprehensive control of schistosomiasis. Vaccine research also ranks among the international similar research. Tang Chongti and Tang's research on ruminant Diptera and Platycladus orientalis is a contribution to the development of animal husbandry.
In the aspect of tapeworm research, Lin Yuguang's research on ruminants and tapeworms, the Veterinary Research Institute of Xinjiang Academy of Agriculture and Animal Husbandry, Lanzhou Veterinary Research Institute of Chinese Academy of Agricultural Sciences and Ningxia Veterinary Research Institute are all beneficial contributions to the study of echinococcosis and its comprehensive control. Li Gui expounded the life history of the Korean pseudocephalus bat in the period of 1. In the study of cysticercosis, Lanzhou Veterinary Research Institute, Jilin Agricultural University, Hebei Medical University, Harbin Medical University and the Second Medical University of PLA have done a lot of research in epidemiology, drug control and immune prevention, including the development of nucleic acid vaccines.
China People's Liberation Army Quartermaster University (Changchun Agriculture and Animal Husbandry University), Nanjing Agricultural University, Nanjing Institute of Military Medicine, China Agricultural University (Beijing Agricultural University) and Shanghai Institute of Livestock Parasitology have all brought the research on trypanosomiasis in China to a new stage in terms of geographical strains, immunization and vaccine development.
In the early 1960s, Lin Kunhua first conducted research on chicken coccidiosis and its control in China. Later, Beijing Agricultural University, South China Agricultural University and Shanghai Institute of Livestock Parasitology made great achievements in species identification, ultrastructure, immunity and drug resistance of chicken coccidia, duck coccidia, rabbit coccidia, cryptosporidium and Sarcocystis. The application of DNA probe, PCR, RAPD and other molecular biology techniques in many aspects has made this kind of research enter the advanced ranks of similar research in the world. In terms of practical immunization technology, the widely used chicken coccidia vaccines at present include wild virus vaccine, attenuated vaccine (early reproductive attenuated vaccine, physical and chemical attenuated vaccine) and late mature vaccine.
Lanzhou Veterinary Research Institute, Changchun Agriculture and Animal Husbandry University, Huazhong Agricultural University and Xinjiang Veterinary Research Institute have made outstanding contributions to the pathogen, life history, geographical distribution, immunization and vaccine development of pear-shaped diseases (Babesia and Protozoa Taylor). Theileria annulata vaccine is the first parasite vaccine that is close to industrial production in China, and it has played an important role in the prevention and treatment of this disease.
2. Textbooks and monographs: Livestock Parasitology and Invasive Diseases edited by Xiong Dashi and Kong (unified textbook, Agricultural Press), Livestock Parasitology edited by Kong and its revised edition have played an important role in veterinary parasitology education. The local textbook Livestock Parasitology edited by Wang Zhiqi (Shanghai Science and Technology Press, 1978). As a postgraduate textbook, there is Parasitology edited by Kong and Suoxun (China Agricultural University Press, 1998).
Important professional works include: Anthropology of Human and Animal Nematodes, Tang Chongti, 1987, Science Press; Livestock Parasites and Control, edited by Zhao Huiyuan, 1996, Jilin Science and Technology Press; Human and animal parasitology * * * edited by Zhao Huiyuan, 1998, Northeast Korea National Education Press; Animal parasitology, Xu Jinan, Gan Yunxing, 1965, People's Education Press; Avian parasitology, edited by Chen Shuyu and Wang Puqin, 1994, Guangdong Science and Technology Press; Xu Jinan, Animal Parasitic Nematodes, 1975, Science Press; Parasitic Nematodes Research Group, Institute of Zoology, Chinese Academy of Sciences, 1979, Science Press; Suo Xun and Li Guoqing edited Chicken Coccidiosis, 1998, China Agricultural Publishing House; Coccidology-Coccidiosis in Livestock, Poultry and Human Body Zuo Yangxian, 199 1 year, Tianjin Science and Technology Press. 3. Society: 1 In 1995, Kong and others initiated the establishment of Animal Parasitology Branch of China Animal Husbandry and Veterinary Society (commonly known as China Veterinary Parasitology Society), which was established in Guilin, Guangxi in that year and is an academic group of veterinary parasitology in China.
In the same year, under the planning of China's famous parasitologists Zhong Huiyuan, Tang, Mao, Wang Zhengyi, etc., the Parasitology Professional Society of the Chinese Zoological Society (China Parasitology Society for short) was established. Looking at the development history of parasitology and parasitic disease prevention and control in China, we can think that we already have a team that can control the spread of parasitic diseases and ensure the development of animal husbandry, as well as a teaching and research team that can track the forefront of world science and technology; In terms of taxonomic flora and experimental parasitology, it is basically equivalent to the international level, but it can't catch up with the west in quantity because of its late start, small team and low funds. In the field of molecular parasitology, China keeps up with the frontier and tries to catch up. However, due to backward equipment, insufficient funds and poor continuity of the project, it is difficult to reach the estimation level of the same period.
It should be noted that the prevention and control measures of parasitic diseases in China are not perfect, and the necessary prevention and control laws and regulations are lacking, and the existing laws and regulations have not been effectively implemented. In addition, the investment in parasitology research in China is gradually weak, the traditional research is ignored, the frontier research lacks stamina, and the brain drain is serious, which is worrying. 1. New diagnostic technology: The traditional diagnostic method of parasitic diseases is out of proportion to the development of modern science. It is a very important direction to develop fast, standardized, specific and sensitive diagnostic technology. For example, Schnieder et al. (1999) can distinguish Oster, Cedar, Leptospira and Tricholoma with only 1 egg or 1 larva. ZhangLHetal( 1998) confirmed the existence of G6 genotype of Echinococcus granulosus camel strain in China by using mitochondrial genome markers. In general, we should explore the fields of immunity, genetic engineering and biochemistry.
2. Biological control of parasitic diseases: Based on the factors of drug resistance and drug residue, biological control of parasitic diseases may be an eternal development direction. The successful control of coccidiosis in breeders and broilers with live chicken coccidiosis vaccine is a good example. In addition, there are successful applications of pneumococcidia vaccine and pear-shaped worm vaccine. There will be live worms, attenuated viruses and genetically engineered vaccines (such as those for ticks and echinococcosis) in the future. Another major field of biological control is to carry out extensive research on natural enemies of parasites, such as fungi that feed on nematodes and nematodes that feed on insects and ticks (it has been proved that several nematodes will become promising natural enemies of ticks); China People's Liberation Army Quartermaster University (formerly China People's Liberation Army Veterinary University) has been conducting research on parasitic protozoa, such as Cryptosporidium and Giardia, and deadly bacteria and parasites may be found in the future.
3. New parasitic diseases or new epidemics of old diseases: At present, it has been found that neosporosis is an important cause of abortion in dairy cows, and opportunistic or conditional parasitic diseases are on the rise. For example, patients with immunodeficiency syndrome are prone to Chagas disease, Leishmania, Toxoplasma gondii, cryptosporidiosis, cryptosporidiosis and microsporidiosis. Examples of new epidemics of old diseases such as schistosomiasis.
4. Parasite genome project: With the development of human genome work, the plant genome research project is also being implemented. Many parasitologists are also studying the parasite genome. For example, analyzing the genome sequence of Plasmodium falciparum is helpful for the research and development of drugs and vaccines. Through the study of the genome of Caenorhabditis elegans, it is found that the mutation of a single gene of keratin can lead to the defect of keratin and cause the morphological changes of the worm. The study of parasite genome will play an important role in the identification of strains in future epidemiology, and will also explain the polymorphism of parasites.
5. Receptor theory: The research results in the field of receptors have become a * * * knowledge. For example, it has been found that human taste is related to the receptors on the nose, and each receptor molecule may specifically recognize one or more smells; Influenza virus receptors are different in birds and humans, and so on. Now parasite workers are also doing research on parasite receptors, and it is found that some protozoa infect mammalian cells, which is related to GPI receptors.
6. Marine Parasitology: Foresighted scientists worried about the future food shortage of human beings and put forward the idea of "marine pasture", so marine parasitology was born. Parasitologists have found that marine parasites cause huge economic losses to oyster and fish farming; It is also found that marine parasites play an important role in marine ecology.
In a word, 2 1 century is the sublimation stage of immune parasitology and biochemical-molecular parasitology, and the infiltration of new technologies and theories from other disciplines at this stage will produce unexpected results, just as Wilmut applied the classic Xenopus experiment proved by British molecular biologist J.B.Gurdon to the field of sheep cloning.