IgG Check calf test has been used in this study to identify if a failure of passive transfer occurs in neonatal calves by measuring the level of IgG in blood. An adequate level of IgG measured in all calves at 48 hour...IgG Check calf test has been used in this study to identify if a failure of passive transfer occurs in neonatal calves by measuring the level of IgG in blood. An adequate level of IgG measured in all calves at 48 hours, 7 days and 14 days after birth showed level of IgG 1000 mg/dl. This level indicated that they have good passive transfer of immunity. Also, in this study colostrum quality fed to calves was detected using Brix Refractometer. The colostrum is of high quality as it contains 50 mg/ml of IgG. This Brix refractometer can be used on the farm level to estimate colostrum IgG content and monitoring colostrum feeding practices. Colostrum with high quality IgG could provide calves with enough IgG to attain successful passive transfer of immunity. Brix and Obione refractometers provide simple, rapid method for estimating IgG concentration on calf serum, thus considered to be the most common method for determining passive transfer failure.展开更多
The H9N2 subtype avian influenza virus(AIV)inactivated vaccine has been used extensively in poultry farms,but it often fails to stimulate a sufficiently high immune response in poultry in the field,although it works w...The H9N2 subtype avian influenza virus(AIV)inactivated vaccine has been used extensively in poultry farms,but it often fails to stimulate a sufficiently high immune response in poultry in the field,although it works well in laboratory experiments;hence,the virus still causes economic damage every year and poses a potential threat to public health.Based on surveillance data collected in the field,we found that broilers with high levels of maternal-derived antibodies(MDAs)against H9N2 virus did not produce high levels of antibodies after vaccination with a commercial H9N2 inactivated vaccine.In contrast,specific pathogen-free(SPF)chickens without MDAs responded efficiently to that vaccination.When MDAs were mimicked by administering passively transferred antibodies(PTAs)into SPF chickens in the laboratory,similar results were observed:H9N2-specific PTAs inhibited humoral immunity against the H9N2 inactivated vaccine,suggesting that H9N2-specific MDAs might hinder the generation of antibodies when H9N2 inactivated vaccine was used.After challenge with homologous H9N2 virus,the virus was detected in oropharyngeal swabs of the vaccinated and unvaccinated chickens with PTAs but not in the vaccinated chickens without PTAs,indicating that H9N2-specific MDAs were indeed one of the reasons for H9N2 inactivated vaccine failure in the field.When different titers of PTAs were used to mimic MDAs in SPF chickens,high(HI=12 log2)and medium(HI=log 9 log2)titers of PTAs reduced the generation of H9N2-specific antibodies after the first vaccination,but a booster dose would induce a high and faster humoral immune response even of PTA interference.This study strongly suggested that high or medium titers of MDAs might explain H9N2 inactivated vaccine failure in the field.展开更多
文摘IgG Check calf test has been used in this study to identify if a failure of passive transfer occurs in neonatal calves by measuring the level of IgG in blood. An adequate level of IgG measured in all calves at 48 hours, 7 days and 14 days after birth showed level of IgG 1000 mg/dl. This level indicated that they have good passive transfer of immunity. Also, in this study colostrum quality fed to calves was detected using Brix Refractometer. The colostrum is of high quality as it contains 50 mg/ml of IgG. This Brix refractometer can be used on the farm level to estimate colostrum IgG content and monitoring colostrum feeding practices. Colostrum with high quality IgG could provide calves with enough IgG to attain successful passive transfer of immunity. Brix and Obione refractometers provide simple, rapid method for estimating IgG concentration on calf serum, thus considered to be the most common method for determining passive transfer failure.
基金This study was supported by grants from the National Key Research and Development Plan(Nos.2016YFD0500204 and 2017YFD0500800)National Natural Science Foundation of China(Nos.31772753,31572543,31700136 and 31702237)+1 种基金Shanghai Municipal Natural Science Foundation(No.17ZR1437400)the Project of the Shanghai Science and Technology Commission(No.17391901700).
文摘The H9N2 subtype avian influenza virus(AIV)inactivated vaccine has been used extensively in poultry farms,but it often fails to stimulate a sufficiently high immune response in poultry in the field,although it works well in laboratory experiments;hence,the virus still causes economic damage every year and poses a potential threat to public health.Based on surveillance data collected in the field,we found that broilers with high levels of maternal-derived antibodies(MDAs)against H9N2 virus did not produce high levels of antibodies after vaccination with a commercial H9N2 inactivated vaccine.In contrast,specific pathogen-free(SPF)chickens without MDAs responded efficiently to that vaccination.When MDAs were mimicked by administering passively transferred antibodies(PTAs)into SPF chickens in the laboratory,similar results were observed:H9N2-specific PTAs inhibited humoral immunity against the H9N2 inactivated vaccine,suggesting that H9N2-specific MDAs might hinder the generation of antibodies when H9N2 inactivated vaccine was used.After challenge with homologous H9N2 virus,the virus was detected in oropharyngeal swabs of the vaccinated and unvaccinated chickens with PTAs but not in the vaccinated chickens without PTAs,indicating that H9N2-specific MDAs were indeed one of the reasons for H9N2 inactivated vaccine failure in the field.When different titers of PTAs were used to mimic MDAs in SPF chickens,high(HI=12 log2)and medium(HI=log 9 log2)titers of PTAs reduced the generation of H9N2-specific antibodies after the first vaccination,but a booster dose would induce a high and faster humoral immune response even of PTA interference.This study strongly suggested that high or medium titers of MDAs might explain H9N2 inactivated vaccine failure in the field.
