Genes and Flu
The flu is just a disease. A disease may strike one species and not another species. Well it seems certain genetic markers are all it takes. A genetic variant which explains why Chinese populations may be more vulnerable to H1N1 swine flu has been found by researchers at the University of Oxford and Beijing Capital Medical University. This finding could help identify those at high risk of severe infection and help prioritize those in highest need of treatment. The study led by Dr Tao Dong of the University of Oxford showed that people with a specific genetic variant are six times more likely to suffer from severe influenza infection than those without.
Influenza, commonly known as the 'flu' , is an infectious disease of birds and mammals caused by RNA viruses of the family Orthomyxoviridae, the influenza viruses. The most common symptoms are chills, fever, sore throat, muscle pains, headache (often severe), coughing, weakness/fatigue and general discomfort. Although it is often confused with other influenza-like illnesses, especially the common cold, influenza is a more severe disease caused by a different type of virus. Influenza may produce nausea and vomiting, particularly in children, but these symptoms are more common in the unrelated gastroenteritis, which is sometimes inaccurately referred to as stomach flu or 24-hour flu.
The particular variant rs12252-C is occasionally found in Caucasian populations and was already known to be associated with more severe influenza disease. However, the research teams in the UK and China showed that this variant was present in 69% of Chinese patients with severe pandemic (swine) influenza in 2009 compared with 25% who only had a mild version of the infection.
Understanding why some people may be worse affected than others is crucial in improving our ability to manage flu epidemics and to prevent people dying from the virus.
Dr Tao Dong of the Weatherall Institute of Molecular Medicine at Oxford University says: "Understanding why some people may be worse affected than others is crucial in improving our ability to manage flu epidemics and to prevent people dying from the virus. It's vital that we continue to fund research that examines flu from the smallest details of our genetic code, in the populations around the world that continue to be vulnerable to infection."
Better known genetically is that some flues will infect animals and not humans and vice versa.
Wild aquatic birds are the natural hosts for a large variety of influenza A. Occasionally, viruses are transmitted to other species and may then cause devastating outbreaks in domestic poultry or give rise to human influenza pandemics.
Influenza B almost exclusively infects humans and is less common than influenza A. The only other animals known to be susceptible to influenza.
It is thought that the DNA change increases risk of severe infection by limiting the effectiveness of a protein which helps to defend against influenza and similar viruses. This protein, known as IFITM3, has been previously shown to slow down virus replication in mice.
For further information see Chinese Genes.
Genes image via University of Oxford.