The present study was conducted to study the persistence of maternally derived antibody (MDA) in experimentally reared chicks and to compare the level of antibody production in chicks vaccinated with DLS fowl pox vaccine and Diftosec-CT® fowl pox vaccine with their protective efficacies.
Fowl pox virus samples The infected tissues containing scabs or nodules appearing on different parts of the body of chicks (clinical infection) were collected aseptically as per as practicable with the help of scissors, scalpel and forceps and kept in screw capped test tube or vials containing 50% buffered glycerin. The materials were carried out to the laboratory and preserved at - 200C until processed for isolation. Fowl pox virus vaccine Lyophilized live attenuated FPV vaccine produced from LRI, Mohakhali, Dhaka, was collected from LRI, Mohakhali and Freeze dried live Diftosec-CT' vaccine was collected from regional office of Advance Animal Science Co. Limited, Mymensingh maintaining cool chain system. The vaccine was stored at 4-8 0C until use. Chicken Eggs Fertile eggs of white leg horn (WLH) breeds of chicken were procured from Bangladesh Agricultural University (BAU) poultry farm, Mymensingh. These eggs were incubated for 10-12 days at 370C for the development of embryos. Embryos which were found well developed and active by candling were selected for the propagation of pigeon pox and fowl pox viruses and titration of these viruses.
Experimental birds and rabbit A total of 80 day-old chicks of Fayoumi, Sonali Breed (SB) and WLH breed were purchased from the BAU Poultry Farm, Mymensingh. These baby chicks were reared in the poultry house of the Department of Microbiology and Hygiene, BAU, Mymensingh. The birds were provided with recommended feed and other management requirements and were reared under strict biosecurity measures. All media and buffers were prepared freshly Antibiotics (Streptopen' Renata Bangladesh Ltd.) was purchased from local market. Apparently healthy adult rabbit obtained from the Department of Animal Nutrition, Faculty of Animal Husbandry, BAU, Mymensingh and selected for the collection of rabbit serum which was used for PHA test.
Experimental design Eighty day old Fayoumi, SB and WLH chicks were divided into six groups namely A, B, C, D, E and F where group A and F contained 20 chicks but B, C, D and E each group contained 10 chicks. Of these, group A was used to determine the persistence of maternally derived antibody (MDA). Group B, C, D and E were used for vaccination with DLS-FPV and Diftosce-CT' vaccine through usual and suggested schedule of vaccination. Group F kept as unvaccinated control. In order to determine the persistence of MDA in chicks of vaccinated origin, 20 chicks were reared in Group A. Blood samples were collected for the preparation of sera from randomly selected 15 chicks at day 1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31, 34 and 40 of age and subjected of PHA test. To study the comparative efficacy of Diftosec-CT? and DLS-FPV vaccine following usual and suggested schedule of vaccination in chicks, remaining 40 chicks were divided into four groups namely B, C, D and E and each group contained 10 chicks, Chicks of group B and C were vaccinated with DLS-FPV vaccine applying usual and suggested schedule of vaccination at 22 and 18 days of age respectively, on the other hand, the chicks of group D and E were vaccinated with Diftosec-CT? FPV vaccine applying usual and suggested schedule of vaccination at 42 and 22 days of age respectively. To determine the antibody response against FPV vaccine, blood samples were collected to obtain sera at 7, 14 and 21 days of post vaccination from the birds of each vaccinated group and at the same time blood samples were also collected 5 birds of unvaccinated control group. Each bird of vaccinated group and 10 from unvaccinated control were challenged with 10-6 EID50/0.1 ml virulent Fowl pox virus (FPV) after 3 weeks of age. Antibody titres of the collected sera were determined by passive haemagglutination (PHA) test to assess the efficacy of experimentally developed FPV vaccine.