Histopathological Study on Chickens Artificially Infected with Infectious Laryngotracheitis

[Objective] This study aimed to investigate the histopathological changes in chickens artificially infected with infectious laryngotracheitis（ILT）. [Method] Through ar- tificial injection of allantoic liquid containing ILTV into chickens to induce infectious laryngotracheitis, the clinical symptoms in infected chickens were observed; tissues of trachea, lungs, heart, liver, kidney and spleen were collected from dead chickens, and prepared into paraffin sections, followed by histopathological observation under a microscope. [Results] This disease occured in the inoculated chickens 3d later, with a morbidity rate of 95%. The main symptoms were dyspnea, asthma and coughing up of bloody exudate; yellowish-white pseudomembrane was observed on dissected larynx trachea; swelling, haemorrhage, and further erosion were observed on the in- fected tracheal mucosa, resulting in death of chickens, with the mortality rate of 25%; histopathological observation showed that parenchymal organs exhibited exuda- tive inflammation; swelling, degeneration, necrosis and shedding of epithelial cells were observed; disturbance of blood circulation occured.[Conclusion] This study pro- vides reference bases for the treatment of ILT.

Identification of A Field Strain of Infectious Laryngotracheitis Virus Isolated from Jiangsu Province

[ Objective] To isolate and identify infectious laryngotracheitis virus （ILTV） from chickens. [ Method] Larynx, trachea, liver and other organs were collected from infectious laryngotracheitis （ILT）-suspected layers. And ILTV TK gene was amplified from these specimens by PCR for initial diagnosis. Virus fluid was isolated and inoculated into SPF chicken embryos via allantoic cavity and chorioallantoic membrane （CAM）, respectively. Hyaluronic acid in allantoic fluid was detected, and CAM lesions were observed. The definite diagnosis was performed through animal regression test. [Result] A 1.3 kbp fragment was amplified from larynx and its secretion of the ILT-suspected chickens. And its amino acid sequence had 98.5% homology to that of ILTV TKgene published in GenBank. After the chicken embryos were inoculated with the isolated ILFV fluid, pox spots, giant polynuclear syncytial cells having intranuclear inclusion bodies were observed in CAM. After being challenged by the IL TV fluid, the chickens showed typical respiratory symptoms and pathological changes of ILT. [Coudusion] A field strain named ILTV XZ09 was isolated from larynx and its secretion of ILT-suspected chickens.

Screening of Chinese Herbal Medicines against Avian Infectious Laryngotracheitis Virus and Escherichia coli

[ Objective] This study aimed to screen Chinese herbal medicines against avian infectious laryngotracheitis virus and Escherichia coli. [ Method ] Conventional Chinese medicine plate dilution method, plate punching method and test tube method were applied to screen Chinese herbal medicines against avian infectious laryngotracheitis virus based on chicken embryo inoculation experiment. [ Result ] Forsythia suspensa, Radix lsatidis, Isatis iadigotica, Lonicera japonica, Codonopsis pilosula, Astragalus membranaceus, Rhizoma Atractylodis Macrocephalae, C, tyeyrrhiza uralensis and Pericarpium granati had relatively strong anti-ILTV effect; among the Chinese herbal medicines against avian E. coli, Sanguisorba offwinalis, Fructus Mume, Rheum palmatum, Anemarrhena asphodeloides, Radix Scutellariae and Fagopyrum cymosum had relatively strong effect against avian E. coli Os, while other Chinese herbal medicines had relatively weak or no inhibitory effect on avian E. coli 0s and 05. [ Conclusion] This study laid the foundation for further development of Chinese herbal medicine compound preparations to treat avian infectious laryngotracheitis, avian colibacillosis and other viral diseases and bacterial diseases.

Effects of Pak Ning Powder and Oral Liquid Treating Chicken Infectious Laryngotracheitis

[ Objective] To investigate the therapeutic effects of Chinese herbal medicine compound preparation ＂Pak Ning＂ on chicken infectious la- ryngotracheitis. E Methodl ＂Pak Ning＂ with different dosage forms and dosage time were used to carry out clinical observation of artificial infectious and natural infectious ILT of chickens. [ Result] The therapeutic efficacy of ＂Pak Ning＂ oral liquid water was better than powder with high cure rate, the difference was significant （P〈0.05）. compared with Ribavirin, the difference was significant （P 〈0.01 ）, and the preventive effects of feeding in advance were very well. I Conctusionl ＂Pak Ning＂ plays an important role in the treatment and prevention of ILl- with strong infectiosity and high mortality.

Protection Efficacy of Recombinant Infectious Laryngotracheitis Vaccine in Chicks

A commercial recombinant fowl pox vectored infectious laryngotracheitis （ILT） vaccine was examined its protection efficacy in one-day-old chicks by subcutaneous route with various dose-strength. The treatment groups I-III birds were vaccinated with a full, 1/2 and 1/3 dose of recommendation dose, respectively. Thereafter, at 6 wk post vaccination, they were challenged with 5x labeled dose of live ILT vaccine. Protection efficacy of the vaccine was compared among groups based on antibody production and eye lesion score. The results of eye lesion score showed that there was a significant difference between control and treatment groups, whereas the difference was not found among the treatment groups. For seroconversion, there was no significant difference between birds in group I and II. However, higher number of seroconversion birds in groups I and II than group III was observed （P 〈 0.05）. It was concluded that a half dose of recommendation dose had the same protection efficacy as a full dose of recombinant YP-LT vaccine.