The viral invisibility cloak
Previously considered as a silent virus, the bovine leukaemia virus (BLV) produces small molecules - microRNAs - invisible to its victim's immune system. The virus may thus produce these small molecules while remaining hidden in the host cell. This explains why so far BLV was considered to be silent in tumours. These viral microRNAs may thus be the key to understanding how BLV induces cancerogenesis without triggering an immune response in the organism it is infecting. A study published in PNAS by the Animal Genomics Research Unit of GIGA at the University of Liège, headed by Michel Georges looks into this in more depth. Sheep: a uniquemodel‘Once infected by BLV, it takes about ten years on average for cattle to develop leukaemia’, continues Van den Broeke. A characteristic which doesn't make it any easier to study the pathogen's mode of action! Fortunately, scientists don't lack the imagination and ingenuity required to overcome this type of obstacle. As an alternative for studying the virus in its natural host, they use sheep as a research model. When sheep are infected with BLV, the disease progresses much more rapidly than in cattle, and leukaemia develops after an average of eighteen months in all infected sheep (while in infected cattle, only a small percentage, about 2 to 5%, develop leukaemia). When technology pushes the limitsWhat is deep sequencing? The genetic material of living creatures can be compared to a code made up of four letters, the order of which determines which messages are communicated. 'High-throughput sequencing consists of detecting and decoding these messages without a prior knowledge of the the composition of the genome or transcriptome. It may be compared to the generation of millions of words or short sentences which bioinformaticians analyse in order to distinguish the words which mean something from those which don’t ', explains Van den Broeke. (1) Nicolas Rosewick, Mélanie Momont, Keith Durkin, Haruko Takeda, Florian Caiment, Yvette Cleuter, Céline Vernin, Franck Mortreux, Eric Wattel, Arsène Burny, Michel Georges, and Anne Van den Broeke. Deep sequencing reveals abundant noncanonical retroviral microRNAs in B-cell leukemia/lymphoma. Proc Natl Acad Sci U S A 2013 Feb 5;110(6):2306-11. PMID: 23345446. |
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