Genetic engineering unlocks new vaccine for Marek's disease.

Scientists at The Pirbright Institute have used genetic engineering to develop a more efficient and effective vaccine for Marek’s disease which could pave the way for a new generation of poultry disease vaccines. The Marek's disease vaccine (MDV) is currently controlled by vaccination and over 20 billion vaccine doses are administered worldwide each year. Turkey herpes virus (known as HVT), is widely used in the development of avian vaccines as a method of delivering elements of avian pathogens (disease causing agents), into birds to create the immune response that protects them against disease. The technologies currently available for creating HVT recombinant vaccines are difficult and time consuming to use, however. In the case of Marek’s disease, the existing methods also hinder the level of protection the vaccines can offer. Advances in technology have facilitated the development of a new gene editing technique called CRISPR/Cas9 (Clustered Regularly Interspaced Palindromic Repeats/ associated Cas9), which enables greater speed and accuracy in targeting, cutting and editing gene sequences. This technique was used by Dr Yongxiu Yao, to genetically modify HVT; inserting part of the Marek’s disease virus into it to generate a completely new genetically modified (GM) vaccine, which is capable of protecting against the most dangerous strains of the virus. Dr Yao said, “This was a great opportunity to create a new generation of vaccines. HVT is widely used in the production of a variety of avian disease vaccines and genetically engineering it in this way has unlocked its potential to protect against all strains of Marek’s disease virus, as well as other dangerous avian viruses such as bird flu, which is also a danger to humans.