Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.1999.487.489MahboobT. ArshadM. AfzalH. SiddiqueM. 2199922Mukteswar strain of Newcastle disease (ND) virus was propagated in 9-day-old embryonated eggs via allantoic route. The harvested allantoic fluid with haemagglutination (HA) titre of 1024 (EID50 109.3) was inactivated using 0.1 percent formalin solution. Two experimental vaccines were prepared in light mineral oil with aqueous to oil ratio of 1:2 ( MK-VAC-I) and 1:4(MK-VAC-II).The hydrophile lipophile balance (HLB) of the vaccine was fixed at 7,0 using oil phase (span 80) and aqueous phase (tween 80) surfactants. One hundred and twenty, four week old layer chicken were divided into four equal groups (A to D). Groups A and B were injected with two experimental vaccines and C with commercial oil emulsion vaccine keeping D group as non-vaccinated control. Highest four week cumulative haemagglutination inhibition titres were shown by commercial vaccine (226) followed MK-VAC-I (217) MK-VAC-II (171) and lowest by control group. Both the vaccine showed 80 percent protection against virulent virus challenge comparable to the commercial one.]]>Allan, W.H., J.E. Lancaster and B. Toth,19781978Brugh, M.Jr. and H.S. Siegel,197857892896Brugh, M., C.W. Beard and H.D. Stone,197940165169Griffin, W.C.,19791979pp: 900-920pp: 900-920Jeffery, M.S.,19851985pp: 35Landgraf, H. and E. Vielitz,197077393398Mahboob, T., M. Arshad, H. Afzal, M. Siddique and G. Muhammad,199717127130Mohanty, S.B. and S.K. Dutta,1981pp: 80-82pp: 80-82Stone, H.D., M. Brugh, S.R. Hopkins, H.W. Yoder and C.W. Beard,1978Mycoplasma antigens.]]>22666674Stone, H.D., M. Brugh, G.A. Erickson and C.W. Beard,19802499111Stone, H.D., M. Brugh and C.W. Beard,198327688697Stone, H.D.,1988326873Stone, H.D.,199135816