[ Objective] To study the correlation between HI titer and protection against IBV challenge in SPF layers. [ Method ] SPF layers were randomly divided into four groups, namely group A1, A2, B1 and B2. The group A1 was...[ Objective] To study the correlation between HI titer and protection against IBV challenge in SPF layers. [ Method ] SPF layers were randomly divided into four groups, namely group A1, A2, B1 and B2. The group A1 was immunized with H120 live vaccine. The group A2 was first immunized with H120 live vaccine and later boosted with ND-IB-EDS trivalent inactivated vaccine. The group B1 was used as unimmunized chal- lenge control. The group B2 was kept as unimmunized unchallenged control. The blood samples were taken prior and post-vaccination at intervals and HI tests were conducted. At the laying peak, the group A1, A2 and B1 were challenged with IBV M4t virulent strain. The clinical features and egg production of layers were monitored and recorded. [Result] After 30 d post vaccination with H120 live vaccine, the HI titer reached 4.45 log2; after 30 days boosting with ND-IB-EDS trivalent inactivated vaccine, the HI titer reached to 7.35 log2. Before challenge, HI antibody titer in group A1, A2, B1 and B2 were respectively 4.24 log2, 7.40 Iog2, 2.10 log2 and 2.10 log2. After challenge, chickens in unimmunized challenge control group B1 showed respiratory symptoms, egg production dropped by 30.9%, and they produced more soft-shelled, no-shelled or abnormal eggs. In the group A1, some chickens had light respiratory symptoms and egg production dropped by 11.7%. In the group A2, the egg production of all chickens was as normal as the group B2. [ Conclusion] When the HI titer was over 6 log2, challenge by virulent virus had no impact on egg produc- tion; when the HI titer was 5 log2, 4 log2 and less 3 log2, egg production dropped by 6.0%, 11.3% and 29.6%, respectively. Thus, the HI anti- body level in chickens has close correlation with protection against IBV challenge.展开更多
The frequent emergence of drug resistant influenza viral strains emphasizes the urgent and continual need to develop new antiviral drugs. Given the encouraging findings of previous studies on antiviral compounds from ...The frequent emergence of drug resistant influenza viral strains emphasizes the urgent and continual need to develop new antiviral drugs. Given the encouraging findings of previous studies on antiviral compounds from plant sources, this study focused on medicinal plants from Borneo that were traditionally used to treat symptoms of influenza infection. Following the promising results of earlier investigations, four plant extracts that demonstrated multiple modes of viral inhibition were studied against wild-type and neuraminidase (NA) inhibitor-resistant strains of Types A and B influenza viruses. The extracts exhibited more pronounced activities against the wild-type viruses than the NA inhibitor-resistant strains. Variations in the antiviral potential of the extracts collected from different parts of the same plant were also evidenced in the in vitro micro-inhibition assays. Even though all plant extracts affected NA activity of all viruses, only two extracts demonstrated hemagglutination inhibitory (HI) activities against Type A pandemic H1N1 and Type B viruses. Furthermore, Receptor Destroying Enzyme (RDE) treatments of extracts exhibiting HI activities indicated the presence of sialic acid (SA)-like component(s) that may be responsible for HI activity. Since the antiviral potential of extracts was not completely suppressed by RDE, the possibility of non SA-like antiviral components cannot be ruled out. Therefore, synergistic activity between SA-like and non SA-like components contained in the plant extracts may be responsible for the demonstrated antiviral potential. The results also indicated the presence of non SA-like components that may act against other viral proteins apart from hemagglutinin (HA) and NA. Hence, this study supports the presence of multiple antiviral components that act against different viral proteins or interfere with different stages of viral replication. Our results suggest that these plant extracts have the potential to be developed as therapeutic agents for the treatment of influenza and could be a solution to the global occurrence of viral strains resistant to NA inhibitors.展开更多
In the poultry industry, it is common to evaluate the humoral immune response associated to the vaccination calendar used for the different zootechnical purposes. When the vaccine against avian influenza and Newcastle...In the poultry industry, it is common to evaluate the humoral immune response associated to the vaccination calendar used for the different zootechnical purposes. When the vaccine against avian influenza and Newcastle disease currently used in a farm is going to be changed, an important parameter observed to choose a product over the others is based on the antibody titers reached by the application of the new vaccine. This study aimed to compare the serologic results obtained by hemagglutination inhibition （HI） test of avian influenza and Newcastle disease reported in four different national laboratories. One-day-old Ross broiler chickens were kept in Horsfall-Bauer isolation units and were vaccinated subcutaneously for the prevention of avian influenza and Newcastle disease. Then, serum of all the birds was extracted at three, six and seven weeks old and sent to four different national diagnostic laboratories, where HI test was performed for avian influenza and Newcastle disease. The treatments were designed in 4 × 3 factorial. Data showed significant statistical differences between laboratory results （up to six logarithms for influenza at six and seven weeks）. This study confirms that the results of the HI test can vary from one laboratory to another, thus it is important to consider this, when the vaccines against avian influenza and Newcastle disease are evaluated at field.展开更多
文摘[ Objective] To study the correlation between HI titer and protection against IBV challenge in SPF layers. [ Method ] SPF layers were randomly divided into four groups, namely group A1, A2, B1 and B2. The group A1 was immunized with H120 live vaccine. The group A2 was first immunized with H120 live vaccine and later boosted with ND-IB-EDS trivalent inactivated vaccine. The group B1 was used as unimmunized chal- lenge control. The group B2 was kept as unimmunized unchallenged control. The blood samples were taken prior and post-vaccination at intervals and HI tests were conducted. At the laying peak, the group A1, A2 and B1 were challenged with IBV M4t virulent strain. The clinical features and egg production of layers were monitored and recorded. [Result] After 30 d post vaccination with H120 live vaccine, the HI titer reached 4.45 log2; after 30 days boosting with ND-IB-EDS trivalent inactivated vaccine, the HI titer reached to 7.35 log2. Before challenge, HI antibody titer in group A1, A2, B1 and B2 were respectively 4.24 log2, 7.40 Iog2, 2.10 log2 and 2.10 log2. After challenge, chickens in unimmunized challenge control group B1 showed respiratory symptoms, egg production dropped by 30.9%, and they produced more soft-shelled, no-shelled or abnormal eggs. In the group A1, some chickens had light respiratory symptoms and egg production dropped by 11.7%. In the group A2, the egg production of all chickens was as normal as the group B2. [ Conclusion] When the HI titer was over 6 log2, challenge by virulent virus had no impact on egg produc- tion; when the HI titer was 5 log2, 4 log2 and less 3 log2, egg production dropped by 6.0%, 11.3% and 29.6%, respectively. Thus, the HI anti- body level in chickens has close correlation with protection against IBV challenge.
文摘The frequent emergence of drug resistant influenza viral strains emphasizes the urgent and continual need to develop new antiviral drugs. Given the encouraging findings of previous studies on antiviral compounds from plant sources, this study focused on medicinal plants from Borneo that were traditionally used to treat symptoms of influenza infection. Following the promising results of earlier investigations, four plant extracts that demonstrated multiple modes of viral inhibition were studied against wild-type and neuraminidase (NA) inhibitor-resistant strains of Types A and B influenza viruses. The extracts exhibited more pronounced activities against the wild-type viruses than the NA inhibitor-resistant strains. Variations in the antiviral potential of the extracts collected from different parts of the same plant were also evidenced in the in vitro micro-inhibition assays. Even though all plant extracts affected NA activity of all viruses, only two extracts demonstrated hemagglutination inhibitory (HI) activities against Type A pandemic H1N1 and Type B viruses. Furthermore, Receptor Destroying Enzyme (RDE) treatments of extracts exhibiting HI activities indicated the presence of sialic acid (SA)-like component(s) that may be responsible for HI activity. Since the antiviral potential of extracts was not completely suppressed by RDE, the possibility of non SA-like antiviral components cannot be ruled out. Therefore, synergistic activity between SA-like and non SA-like components contained in the plant extracts may be responsible for the demonstrated antiviral potential. The results also indicated the presence of non SA-like components that may act against other viral proteins apart from hemagglutinin (HA) and NA. Hence, this study supports the presence of multiple antiviral components that act against different viral proteins or interfere with different stages of viral replication. Our results suggest that these plant extracts have the potential to be developed as therapeutic agents for the treatment of influenza and could be a solution to the global occurrence of viral strains resistant to NA inhibitors.
文摘In the poultry industry, it is common to evaluate the humoral immune response associated to the vaccination calendar used for the different zootechnical purposes. When the vaccine against avian influenza and Newcastle disease currently used in a farm is going to be changed, an important parameter observed to choose a product over the others is based on the antibody titers reached by the application of the new vaccine. This study aimed to compare the serologic results obtained by hemagglutination inhibition （HI） test of avian influenza and Newcastle disease reported in four different national laboratories. One-day-old Ross broiler chickens were kept in Horsfall-Bauer isolation units and were vaccinated subcutaneously for the prevention of avian influenza and Newcastle disease. Then, serum of all the birds was extracted at three, six and seven weeks old and sent to four different national diagnostic laboratories, where HI test was performed for avian influenza and Newcastle disease. The treatments were designed in 4 × 3 factorial. Data showed significant statistical differences between laboratory results （up to six logarithms for influenza at six and seven weeks）. This study confirms that the results of the HI test can vary from one laboratory to another, thus it is important to consider this, when the vaccines against avian influenza and Newcastle disease are evaluated at field.
