When used in compliance with current antiepizootic measures, vaccine preparations against EIV should http://www.selleckchem.com/products/byl719.html not only be safe and immunogenic, but may also provide the ability to differentiate between infected and vaccinated animals (DIVA strategy); only live recombinant vector vaccines can fully meet the requirements of this strategy as they express only EIV surface proteins [23]. However, animals vaccinated with conventional inactivated vaccines may also be differentiated from infected animals using serological tests which detect antibodies against the nonstructural influenza

viral protein NS1 [24] and [25]; antibodies against NS1 are only formed when live influenza viruses replicate in vivo. The DIVA strategy is not feasible in practice for live attenuated EIV vaccines, since the vaccine virus is similar to the wild-type virus and induces an infectious process in vaccinated animals. However, serological studies have demonstrated that infected animals can be differentiated from animals vaccinated with the modified live vaccine based on the Ca strain A/HK/Otar/6:2/2010. Differentiation was possible as after the prime vaccination – and most importantly after booster immunization

– with the live modified vaccine, yearlings did not show detectable antibody titers (>1:10) in the HAI assay for 12 months PV. On day Veliparib purchase 28 post-challenge with homologous and heterologous viruses at different times PV (1, 2, 4, 5, 6, 9, 12 months), both single and double immunized animals accumulated significant HAI antibody titers (from 168 ± 27 to 672 ± 144). Moreover, it should be noted that the HAI antibody titers were significantly higher in the vaccinated animals, especially in the double vaccinated group, than the control group. Antibodies generated as

a result of the challenge Calpain persisted in the vaccinated and control groups for at least 18 months (time of observation, data not shown). This data suggests that our vaccine will enable the differentiation of infected and vaccinated animals in practice using widely available serological tests such as the HAI. On the basis of this data, for practical use we recommend double intranasal administration of the modified live vaccine based on the Ca strain A/HK/Otar/6:2/2010 at an interval of 42 days. The authors express their gratitude to the staff of the Research Institute of Influenza (St. Petersburg, Russia) for kindly providing the donor attenuated strain A/Hong Kong/1/68/162/35CA (H3N2) vaccine. This work was carried out under the project “Development of Highly Effective Means of Specific Prevention of Equine Influenza” as part of the research program O.0534 “Equine Influenza: Epizoological Monitoring, Developing Means of Diagnosis and Prevention” for 2010–2012 funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan. The funders had no role in the study design, data collection and analysis, decision to publish, or manuscript preparation.