The adjuvant activity of chitosan (CS) and calcium phosphate (CAP) particles was studied following intranasal (mucosal) administration to commercial chickens with inactivated Newcastle disease virus (NDV) vaccine. After three vaccinations with inactivated NDV in combination with CS or CAP an increase in antibody titers in blood and mucosal samples in chickens was observed when compared with the administration of NDV antigen only. A lower level of humoral immunity was observed in broiler chickens compared to layer-type birds. The CS-based vaccine demonstrated higher antigenic and protective activity following lethal challenge than the vaccine containing CAP. Because CS particles efficiently changed mucosal and humoral immunity and protective activity, CS may in the future be considered for use as a potential adjuvant for production of vaccines for poultry.
The novel coronavirus infection COVID-19, caused by the SARS-CoV-2, has triggered a pandemic, and has also been reported in animal populations – in farm minks, dogs and felines: domestic cats, lions and tigers. The susceptibility of some animal species to the SARS-CoV-2 has been proven by experimental infection. Serological methods are effectively used to detect the infection in animals. Currently, methods such as neutralization test, immunofluorescence assay and enzyme-linked immunoassay are used to detect antibodies to coronaviruses. Thanks to these studies, a test kit was developed based on an indirect enzyme-linked immunoassay to detect the SARS-CoV-2 antibodies in sera of susceptible animals. The use of a purified concentrated inactivated virus as an antigen allows the detection of antibodies to various SARS-CoV-2 immunodominant proteins (S and N). The reaction conditions were optimized, and a positive-negative threshold was established by testing of 154 negative sera from animals of six species (ferrets, minks, foxes, arctic foxes, cats and dogs). The method reproducibility analysis showed that the average value of the variation coefficient did not exceed 7%, which is an acceptable value. The specificity and sensitivity of the neutralization test, when testing 30 sera from ferrets was 100 and 92.6%, respectively. The high diagnostic sensitivity and specificity shown by testing of 50 serum samples from minks, foxes, cats and dogs with different immune status, allow us to recommend the developed test kit for screening and monitoring tests and post-vaccination immunity control.
More than 30,000 samples of blood serum from domestic, wild and synanthropic birds from 50 regions of the Russian Federation were submitted to the FGBI “ARRIAH” (Vladimir) Reference Laboratory for Avian Viral Diseases to be tested for avian influenza and Newcastle disease within the framework of monitoring activities conducted by the Rosselkhoznadzor in 2019. As a result of the laboratory diagnosis, antibodies to type A influenza virus were detected in vaccinated chickens from two poultry farms in the Perm and Primorsky Krais (A/N9). The detected antibodies were specific to the haemagglutinin subtype of the vaccine antigen. As for the backyards in the RF Subjects, where scheduled vaccination against avian influenza A/H5 is carried out, a low level of immunity was seen in the Rostov and Astrakhan Oblasts (35 and 44%, respectively) while a high level of immunity was observed in the Republic of Altai, Krasnodar Krai, the Chechen Republic and the Primorsky Krai (69, 78, 80 and 88%, respectively). High seroprevalence of Newcastle disease virus in adult poultry in indoor holdings was associated with mass vaccination against the disease. In broiler chickens, post-vaccination antibodies were observed, on average, in 42% of the studied blood serum samples. Antibodies to the Newcastle disease virus were detected in 39% of samples from backyard chickens. Seroprevalence in wild and synanthropic birds was high. The obtained results suggest that the risk of introduction and spread of avian influenza and Newcastle disease in industrial poultry farms and in backyards remains.
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