Infectious diseases caused by viral pathogens constitute a considerable public health threat. Viruses such as HIV, dengue virus, influenza and Ebola, are responsible for many cases of potentially fatal diseases, with outbreaks particularly prevalent in tropical regions and the developing world. Pathogens such as herpes simplex virus (HSV), Epstein-Barr virus (EBV), human papillomavirus virus (HPV) and hepatitis C infect millions of people worldwide. Much work is still required by scientists to control outbreaks of existing and emerging viral strains.