Field of Science

Are microbes evolving to escape vaccination?

What if all those vaccines - those ones that work really well - all stopped working? Imagine if the viruses and bacteria from which they are trying to protect you against, evolved and adapted to life in a largely immune population? Those robust antibody and T cell responses generated within a person following vaccination supply the perfect breeding ground for the selection of resistant mutants where anibodies can no longer recognise and neutralize their targets and where T cells fail to eliminate infected cells. So, is it possible and is it happening?

Well, we already know this kind of phenomenon from influenza, right? Every year we have to change the strains that are put into your flu jab to match those viruses predicted to be circulating come winter. This is based on generating an antigenic match of vaccine to wild virus; specifically, their surface HA proteins must look the same. This is why there has been such a push to develop universal influenza vaccines capable of immunizing people against all flu strains. For viruses like measles and mumps however, we have our universal vaccine, or at least we thought we did.

Influenza may change through antigenic drift and shift forcing us to develop new vaccines each year, but do other viruses evolve through antigenic drift and force us to generate improved vaccines for them?

Revisiting the origins of contagion - the measles story

The mechanisms behind the incredible infectiousness of measles are poorly understood - that is, until now, where two studies have now come forward investigating the molecular biology of measles person-person transmission. Two groups have independently identified the protein, nectin-4 (a cell adhesion molecule) as the receptor allowing measles to infect and emerge from the respiratory tract and spread from person to person, potentially filling in a major gap in our understanding of this important human pathogen.

The measles virus is one of - if not the most - infectious agents currently circulating in human populations. It is also responsible for considerable disease and death worldwide, particularly across the developing world. But luckily, the introduction of a live-attenuated vaccine has significantly reduced it's incidence - this is in spite of a number of recent outbreaks associated with reduced vaccination rates.