There are many explanations for this. Lets start with the formulation: do you know that by combining the antigens, nothing happens to them? DO they stay in solution, do they form aggregats, etc. Have you checked this? When it comes to the immunological response, more is not always better. There are many example of multivalent vaccines in Veterinary Medicine which don't work as well as the single antigen, because the antigen reaction counteracts each other, because the host immune system is overwhelmed etc. And antibody response may not be everything. NOt sure whether this helps, but if you provide some more infos, I may be able to reply more specific.

Thanks Dirk,

Its CsCl purified adenovirus construct. Aggregate formation is unlikely. Weinjected 5x10^9 pfu each of the three constructs separately. It worked. When we combined all the three i.e. 3x5x10^9, it didn't work. It may be due to overwhelming of host immune system? 

Just to clarify - you used 3.5x10^9 of each? That might be a lot...have you tried different dosage?

I am agre with Dirk Werling. Some time the over dosage is no good for immunity responce. You can try also cobination from two Ag (A+B; B+C; C+A) in different dosage.

Hi Dirk, each antigen @ 5x10^9 (this is the recommended dose to achieve favourable immune response). When three antigens are combined it is 3x5x10^9 (i.e.15x10^9). It must be lot! 

Hi Velizar, thanks. We had to do the trial with trivalent vaccine only. But may be as Dirk suggested we should try with reduced dose. But my question is when the recommended dose for each antigen is 5x10^9 pfu, by reducing antigen quantity by half in trivalent vaccine (say for example 3x2.5x10^9 instead of 3x5x10^9), corresponding immune response against each of the antigen will not reduce?

Dear All

Related to the question, I saw some nice papers and putting here web link:-

doi: 10.1111/j.1365-2567.2004.01903.x

Cellular immune responses induced in cattle by heterologous prime–boost vaccination using recombinant viruses and bacille Calmette–Guérin

http://www.ncbi.nlm.nih.gov/pubmed/10425237

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1782509/

yes I agree with the different previous remarks. My way to obtain a multivalent antiserum is to never inject more than the minimal dose required for a simple antigen thus here you need to add jsu a third of each to make doses for immunisation. To circumvent the possible competition of reaction between antigens that could limit individual responses, I choose generally the strategy to sensibilize animals with antigen + eliciter separately (generally, one each week repeated two times before one month resting and mixt of antigen injection for immunization test.

best regards

Hi, Dirk's all points are valid, the major issue could be the overloading of the immune status of the and also keep an eye on the serum protein levels and overall body condition of the animals. To rule out the interaction between the antigens, you can try by combining two antigens first in different combinations as Velizar suggested, on a small level. Have you tried the same combination in lab animals, if yes, what was the outcome?

Cheers

In multi-valent vaccines, they have been normally tested so that they dont interact/overload the immune response, and thats why some vaccines can not be given in the same syringe. Theoretically, the dose recommended always contains a "safety buffer", to ensure that all vaccinated animals show a response. Thus, I guess the only way you can find out is by i.e. using a third of the recommended dose, and see what answer (and protection) you will achieve. Another possibility is to give the three different vaccines at the same time, but at different sites, i.e. left-right shoulder, and a rear site. Thus, you would hopefully trigger a local response (in the regional draining Lymphnode), which may not result in a complete immunosuppression. However, as before, it is trial and error :-)

Thanks everyone for giving me ideas which will help me in future experiments.

Hi, low antigen dose at priming might also benefit the memory: this paper is very nice

Differentiation of memory B and T cells.

Kalia V, Sarkar S, Gourley TS, Rouse BT, Ahmed R.

Curr Opin Immunol. 2006 Jun;18(3):255-64. Review.