Use of the Human Vaccine, Mycobacterium bovis Bacillus Calmette Guérin in Deer

Abstract

The only vaccine ever approved for human tuberculosis was developed a century ago from an isolate of Mycobacterium bovis derived from a tuberculous cow. Initial safety and efficacy studies of an attenuated version of this isolate were conducted in cattle and other animals. In 1921 the first human, an infant, was orally dosed with this attenuated strain that came to be known as M. bovis bacillus Calmette-Guérin (BCG); named for Albert Calmette and Camille Guérin, the two French scientists that developed the strain. Since 1921, billions of people have been vaccinated with BCG making it the oldest, most widely used, and safest vaccine in use today. It is also the tuberculosis vaccine most studied for use in wildlife, including deer. While BCG vaccination of deer may not reliably prevent infection, it consistently decreases lesion severity, minimizing large, necrotic lesions, which often contain large numbers of bacilli. It is believed that decreased lesion severity correlates with decreased disease transmission; however, this hypothesis remains to be proven. Safety studies in white-tailed deer show BCG may persist in lymphoid tissues for up to 12 months; a factor to be considered in deer used for food. Beyond efficacy and safety, methods of vaccine delivery to free-ranging deer are also under investigation, both in the laboratory and in the field. The ideal delivery method is effective, efficient and safe for non-target species, including livestock. Ingestion of BCG by cattle is of special concern as such cattle may present as “false positives” using currently approved diagnostic methods, thus interfering with efforts by animal health agencies to monitor cattle for tuberculosis. An effective BCG vaccine for deer would be of value in regions where free-ranging deer represent a potential source of M. bovis for livestock. Such a vaccine would also be beneficial to farmed deer where M. bovis represents a serious threat to trade and productivity.

Ex vivo Platforms to Study the Primary and Recall Immune Responses to Intracellular Mycobacterial Pathogens and Peptide-Based Vaccines

“…The use of BCG as a vaccine in humans has shown it is not fully effective ( 20 ). Extensive studies in cattle have shown it is not effective as a vaccine in its present form ( 21 , 22 ). Efforts to increase its efficacy through further genetic modification has not been successful.…”

Occupational exposure and challenges in tackling M. bovis at human–animal interface: a narrative review

“…A review by Buddle et al ( 2018 ) proposed that the adoption of oral Bacillus Calmette Guerin (BCG) vaccination could be one of the approaches that can effectively control and confer protection in wild animals such as European badgers, wild boar, brushtail possums, and deer against bovine tuberculosis (Buddle et al 2018 ). Likewise, another review by Palmer and Thacker ( 2018 ) also documented that the alleviation of disease severity in deer vaccinated with human BCG are likely accompanied by reduction in disease transmission which in turn can diminish the spreading of M. bovis infection to livestock from wild animals (Palmer and Thacker 2018 ). Nevertheless, to optimally utilise BCG vaccine, it will be imperative for the continuity of field test BCG vaccine in numerous animal species under different environments, husbandry systems, varying levels of disease prevalence and the evaluation of the practicality of differentiate infected from vaccinated animals (DIVA) tests (Buddle et al 2018 ).…”

Challenges for controlling bovine tuberculosis in South Africa

“…The aim of vaccinating domestic or wild M. bovis reservoir species is to induce an immune response that ideally protects the animals against infection. However, incomplete protection, meaning infection not being prevented in the vaccinate, is still highly beneficial if the infection cannot progress to a disease, resulting in significantly reduced disease severity (Palmer & Thacker 2018). Several TB vaccine approaches have been explored in humans and in animals; compared to subunit and DNA vaccine candidates, Bacillus Calmette-Guerin (BCG) appears to be the most successful candidate in animals.…”