不同浓度甲醛对几种禽用疫苗病毒灭活效果的研究

为了探究不同浓度甲醛对几种常用禽类疫苗病毒的灭活效果,分别使用浓度为0.1%、0.15%、0.2%、0.25%、0.3%甲醛溶液对鸡新城疫病毒(NDV LaSota株)、禽流感病毒(AIV H9亚型HL株)、减蛋综合征病毒(EDSV AV127株)3种病毒进行灭活试验,观察其灭活前后的效价变化,以便找到各种病毒用甲醛灭活的最佳浓度。结果:NDV在37 ℃条件下用浓度为0.1%、0.15%、0.2%、0.25%、0.3%甲醛溶液灭活16～18 h效价分别下降了2、2、3、4、5个滴度;AIV分别下降了1、2、3、3、4个滴度;EDSV分别下降了1、1、2、2、3个滴度。其中3种病毒全部被灭活。以上结果表明:NDV在灭活时选用浓度为0.1%～0.15%的甲醛溶液为最佳:在灭活AIV时选用浓度为0.1%的甲醛溶液为最佳;灭活EDSV时选用甲醛溶液最佳浓度为0.1%～0.15%。

A Semi-quantitative Serological Method to Assess the Potency of Inactivated Rabies Vaccine for Veterinary Use

Potency is one of the most important indexes of inactivated vaccines.A number of methods have been established to assay the potency,of which the NIH test and single-dose mouse protection test are the "prescribed methods".Here,we report a method to semi-quantitatively assay the potency of an inactivated rabies vaccine,which uses fewer animals and takes less time to complete.Depending on the quality requirements of a vaccine(e.g.minimum potency),a rabies reference vaccine is,for example,diluted to the minimum potency,and 50 μL of the dilution is taken to inoculate 10 mice.The same amount of the test rabies vaccine is inoculated into another 10 mice.After two weeks,all mice are bled and serum samples are assayed for viral neutralizing antibody by the fluorescent antibody virus neutralization(FAVN) test.By comparing the median and interquartile range of antibody titers of the reference vaccine with those of the test vaccine,the test vaccine potency can be semi-quantitatively judged as to whether it is in accord with the required quality.The reliability of this method was also confirmed in dogs.The procedure can be recommended for batch potency testing during inactivated rabies vaccine production.

Evaluation of the Pathogenicity and Immune Response of Nervous Necrosis Virus Isolated in Vietnam

Eight strains of nervous necrosis virus （NNV） isolated in Vietnam were used to detect the pathogenicity and immune response in sea bass （SB）. All strains induced cytopathic effect in SB cell line, complete destruction of monolayer of cells appeared after seven days post infection （dpi）. Virus titer was different for each strain, TCIDso ranged from 102.7 to 1069, and LDs0 from 1015 to 1075. Five NNV strains named QN 02, QN 05, QN 07, ND 11 and KH 05 had higher virulence than the other three, the first causing 100% mortality in experimental fish 3-5 dpi. NNV KH 05 had the highest antigenic similarity, and it was inactivated completely by 0.2% formalin, 0.002 mol/L binary ethylenimine （BEI） and 0.1% beta-propiolactone. The neutralization antibody titer obtained in fish of groups immunized by BEI 0.002 M and beta-propiolactone 0.1% inactivated virus was four to eight times higher than that of the group treated with the formalin inactivated virus. The antibody titer in fish immunized with beta-propiolactone inactivated virus was more persistent. The efficacy of vaccines developed from beta-propiolactone inactivated virus and aluminium hydroxide （AH） or aluminum phosphate （AP） was observed by intramuscularly immunizing Epinephelusfuscoguttatus size 1.5 cm. Neutralizing antibodies appeared in vaccinated fish on 10th day post-immunization （dpi） at a dilution of 1：16; 1：32 and highest levels were reached on 30-45 dpi, at dilutions of 1：256 and 1：512, after treatment with AH and AP vaccine, respectively. The relative percent of survival （RPS） of vaccine at 30 dpi was highest with challenge doses 0.2-1 × 10^6.8 TCIDs0, the RPS varied from 80%-83.3% in both groups of AH and AP immunization. This result provides the basis for developing a vaccine against NNA disease.