Changes in blood cell count in chickens vaccinated as newly-hatched against Marek's disease using HVT FC 126 by means of nebulisation

Marek's disease is one of the greatest problems in poultry production today and vaccination is one of the most important ways of prevention. An innvoative method of vaccine delivery by means of nebulisation was used for vaccination of newly hatched chicks using HVT FC 126 and its impact on blood cell count (WBC, RBC and differential cell count) and H/L ratio was measured. The trial was performed from day 1 to day 21 of life of newly hatched male chicks. Standard blood cell count was performed in a Neubauer hemocytometer, and differential cell count on blood smears stained with MayGrunwald-Giemsa. Blood for that purpose was taken from the jugular vein. The results show a significantly higher WBC count in the group vaccinated by means of nebulisation than in the non-vaccinated groups on day 5 of the trial, and from the group that received only physiological solution, on day 14. In the RBC count there were fluctuations but without any significant differences between the groups during the trial. In differential blood cell count, there were some significant differences on days 7 and 21 of the trial, but no differences in H/L ratio. These results show that vaccination by means of nebulisation significantly influenced the blood cell count but all changes were within the physiological range. Nebulisation as a method of vaccination could probably improve the immune response to the wild Marek's disease virus, mimicking natural infection via the respiratory system and as a mass form of vaccination could be a powerful method for delivery of recombinant HVT vaccine.