Thursday, February 28, 2013

How the Paramyxovirus Evades Human Innate Immunity

Paramyxoviruses represent a class of single-stranded RNA viruses that include the measles, parainfluenza, Sendai and Nipah viruses.  The resulting infections associated with these viruses involve respiratory ailments, and ubiquitous childhood diseases.   Paramyxoviruses – associated diseases represent a significant public health concern especially among children and the elderly.   The major route for disease transmission is via respiration.   Although measles has decreased dramatically in the developed world due mainly to extensive vaccination programs, it continues to be problematic in Africa and Central and South America.
The human immune system is equipped with two tiers of defense against viral infections – the innate and adaptive systems.  The innate system represents the first line of defense.  Within this line of defense, the retinoic acid – inducible gene 1 (RIG -1) – like melanoma differentiation – associated protein 5 (MDA5) senses a broad spectrum of viruses in the form of their cytoplasmic viral RNAs and subsequently activates antiviral innate immunity.
Through the process of biological evolution, viruses have developed diverse mechanisms to evade the innate immune system.  It has been shown that Paramyxovirus, manages to effectively subvert this immunological defense mechanism.  How this is accomplished is poorly understood.  Dr. Carina Motz and colleagues at the Department of Biochemistry and Gene Center at Ludwig – Maximilians University in Munich, Germany have labored painstakingly to elucidate the mechanism of this evasion.

They were able to demonstrate that this class of viruses elaborates a protein product – Paramyxovirus V Protein – that is able to alter the configuration of the host MDA5 protein in such a way as to effectively inhibit its antiviral signaling function.  The end result of this interaction is a compromised first line of defense.

Such studies add significantly to the body of information that helps explain how certain types of virus infections lead to disease in spite of host defense mechanisms.  This information may prove to be invaluable in regards to potential cures and treatments of intractable ailments. 

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