Studies on the development of Newcastle disease killed vaccine
The major advantage of killed vaccines
is their safety; the disadvantages are that they often require multiple doses to elicit and sustain an effective immune response and that the immune response may be imbalanced, leading to subsequent potentiation of the disease (14,15).
Combination of live and killed vaccine
may be a solution to control the disease (Folitseet al.
Key words: Newcastle disease killed vaccine
commercial live vaccine broiler.
Vaccination program is only effective with strict biosecurity measures Live and killed vaccines
are commonly used all over the world (Whithearils, 1996).
Safety is a big factor in killed vaccines
, but they do not stimulate as strong an immune response as modified live vaccines.
Recombinant: Similar to killed vaccines
in that they are noninfectious, recombinant vaccines are produced using DNA technology to induce bacteria to produce proteins that are subsequently administered to induce an immune response.
Infectious bronchitis virus (IBV) mostly infects chicken (Gallus gallus) and is ubiquitous in Asia since 1967 (Lohr, 1981), despite the use of live attenuated and killed vaccines
. It is highly contagious disease (Colvero et al., 2017) and present everywhere especially where poultry are present and it can spread very quickly in non-vaccinated birds.
. Killed vaccines
are conventional types of vaccines prepared by killing the infectious agent and using it as an antigen to induce an immune response.
Traditional avian influenza (AI) vaccines are killed vaccines
, produced either by conventional methods or by reverse genetics  which provide good protection against the clinical disease caused by HPAIVs and significant reduction in viral shedding, if the vaccine seed strain is antigenically matched to the challenge strain .
Availability of a cell line of intestinal origin that supports PEDV replication may be of value for studying mechanisms of virus-cell interactions and for developing live attenuated and killed vaccines
. 7 DOI: http://dx.doi.org/10.3201/eid2103.141658
on the other hand usually require two doses, the first to prime the system and the second a short period later to produce the protective immunity with regular boosters.