Commercial Development of Haemophilus, Actinobacillus and Pasteurella Vaccines

Abstract

It is now 115 years since the work of Louis Pasteur on fowl cholera heralded the dawning of a new era in the control of bacterial diseases by vaccination. The causative organism was later identified as Pasteurella multocida which can be considered as the elder statesman of the group of bacteria we now refer to as HAP. In view of the prominent role of a member of this group in those pioneering days it would be reasonable to assume that todays vaccines reflect the sum total of 115 years of continued research and development. Pasteur’s studies on fowl cholera involved the evaluation of the virulence of P. multocida isolates in infected birds (Pasteur, 1880). Serendipity probably played a key role in this discovery of the concept of attenuation whereby strains maintained in his laboratory not only lost the ability to produce disease but also induced protective immunity against subsequent infection with a virulent strain. Nevertheless, Pasteur realised the implications of these results and went on to apply this approach to other diseases, notably anthrax and rabies. Soon afterwards, it was shown that inactivated vaccines could also induce protective immunity. On the face of it, we have made very little progress in vaccine technology since Pasteurs day as evidenced by the type of vaccines currently available i.e. live vaccines attenuated by non specific procedures and killed bacterins. Moreover, P. multocida continues to be a significant problem for poultry producers and in addition is implicated in other diseases particularly of cattle and pigs. Similarly, the vaccines on the market for other members of the HAP group seemingly owe more to Pasteurs research than subsequent work. One of the contributing factors to this state of affairs is the emphasis that has been placed on antimicrobial therapy as a means of controlling disease rather than prophylactic immunisation, although increasing concerns over antibiotic resistance and residues may be factors in the renewed interest in vaccine development.