1 Infectious laryngo tralheitis (ILT) is an acute respiratory infection caused by infectious laryngotracheitis virus. The disease spreads rapidly and has a high mortality rate. Chickens of different ages are susceptible. The virus is present in the trachea and upper respiratory secretions and is transmitted through the cough of blood and mucus. When exposed to stress, infected chickens with ILLB can be activated, and can be replicated and discharged in large quantities; chickens vaccinated with live vaccines can be detoxified for a longer period of time. Therefore, prolonged exposure of susceptible chickens to chickens vaccinated with live vaccines is also available. Infected with the disease; contaminated litter, feed, and drinking water can become the media. ILT has been reported for the first time since the American Mag and Tcttsles in 1925. The disease has occurred or spread in many countries and regions. In 1986, a seropositive case was first detected in China. In 1992, the virus was isolated. At present, the disease is one of the serious respiratory infectious diseases in China's chicken industry. Since TLTV multiply in the laryngotracheal mucosal epithelial cells, it causes inflammation of the larynx and trachea (inflammation can also spread to the bronchi). Trachea and bronchial secretions, as well as secretions and necrotic cells in the lungs and air sacs, or infraorbital sinusitis during inflammation, enter the trachea and bronchi can cause highly breathing difficulties and even suffocation in sick birds. Occasionally, a cheese-like pseudomembrane forms on the larynx trachea mucous membranes, blocking the airways and causing sick birds to suffocate. The disease spreads quickly in vulnerable chickens, the infection rate can reach 90%, the mortality rate is 5% to 20%, especially the mortality rate of high-yielding chickens is high. ILTV can invade the chicken through the respiratory tract, digestive tract and eyes, multiply in the laryngeal and tracheal epithelial cells, and form intranuclear inclusion bodies in the epithelial cells of the breeding site. Laryngeal tracheal inflammation is serous, mucinous, fibrinous and necrotizing. There are obvious bleeding lesions at each stage of the disease. A large number of viruses are present in the tracheal tissues and exudates of diseased chickens. The pathogenicity and antigenicity of different strains of ILTV are different, but there is only one serotype. As the virulence of different strains on chickens varies greatly, it is difficult to control the disease. 2 Once a chicken farm has had this disease, it will inevitably develop disease after immunization with attenuated laryngotracheitis attenuated vaccine. The chicken farmer who has been vaccinated against the disease has been worried about it. Therefore, an effective, non-responsive, non-poisonous vaccine has always been needed by the majority of chicken farmers. As far as the domestic situation is concerned, there are few cases of commercial chickens and parental mycoplasma-negative chickens. However, after positive chickens have been vaccinated with infectious laryngopharyngitis attenuated vaccines, reactions or even deaths are inevitable. After the reaction, there is a need for cost treatment. Therefore, the immunity of infectious laryngotracheitis has been plagued by domestic chicken farming. 3 The fowlpox virus expression vector is one of the viral vectors that has been constructed to express exogenous genes. It has obvious advantages in expressing foreign genes: (1) Its genome structure is huge and it can tolerate large exogenous sources. Genes (25-35 kb) are inserted at different sites in their genome. (2) Strict intracytoplasmic replication avoids the possibility of viral gene recombination into the host cell chromosome, and the host range of fowlpox virus is relatively narrow, so the safety is high. (3) The process of post-translational modification of the expression product (protein) is very similar to that in vivo, and therefore has high activity and retains the corresponding antigenicity and immunogenicity. Based on the above characteristics, the fowlpox virus vector can not only be used as a vector for avian-derived vaccines, but also can be used as a genetically engineered live vector vaccine for mammals and even humans, and has broad application prospects. 4 There are currently two vaccines for immunization of chickens. One is an attenuated vaccine that has been vaccinated against the eye, but the vaccine is generally more virulent. Four days after the eyelid, there is a different degree of reaction, snoring, tearing, closing eyes, eating less or not eating; severe and natural symptoms are the same , bloodshed, causing death, even worse, caused deaths in batches, the vaccine response lasted 30 to 45 days. Especially the positive chickens of mycoplasma, the response after the vaccine is more serious, and the first free time should not be too late, otherwise there will be a stronger response. The other is a virulent vaccine that can be rubbed in the cloacal mucosa. After 4 to 5 days, the mucosa develops edema and hemorrhagic inflammation. However, the risk of detoxification is very high. A special brush is needed and it is generally used only in affected chicken farms. Regardless of the virulence of the vaccine, it can only be used in the affected area or in the area where the disease has occurred, because the chickens vaccinated with the above vaccine can still discharge the virus to the outside world. 5 Infectious laryngotracheitis and chickenpox gene engineering live vector vaccine developed by Harbin Veterinary Research Institute (referred to as the double-laryngealpox vaccine) is a genetically engineered vaccine expressing fowlpox virus as a carrier for infectious laryngotracheitis virus gB. (A chicken embryo fibroblast cell culture expressing the recombinant fowlpox virus of the chicken infectious laryngotracheitis virus gB was repeatedly freeze-thawed and then freeze-dried to prepare a freeze-dried protective agent). Through the clinical application of millions of chickens in the past few years, the vaccine has the following advantages. 5.1 Easy to use: It can be used for stabbing or shallow muscle injection. The throat pneumococcal double-injection vaccine specification is acupuncture immunization, but after the author diluted with saline, the superficial muscle of the wing root is injected with 0.1-0.3 ml, the immunization dose is accurate, and the operation is rapid. 5.2 There was no adverse reaction after immunization with this vaccine. Two immunizations were performed at 21 to 35 days and 85 to 95 days, respectively. After immunization, no abnormalities were found in the spirit, feeding, and drinking of the chickens. No adverse reactions were observed even after immunization with chickens at the peak of egg production. If the first basic immunization was not performed, no adverse reactions were observed in the second-time immunization. No adverse reactions were observed after vaccination with the positive flocks of mycoplasma infection. 5.3 Inoculation with 2 times the amount of vaccine to be injected in the outbreak of ILT can effectively control the development of the disease. 5.4 The author believes that the vaccine is an ideal vaccine for the prevention of infectious laryngotracheitis and can replace the above two attenuated vaccines. Embedding Cassette,Embedding Cassette Plastic,Plastic Embedding Cassette,Lab Embedding Cassette Luck Medical Consumables Co.,LIMITED , https://www.luckmedical.com