There is new evidence showing that HIV is fickle and difficult to cure. Chinese and Canadian scientists published an article in the American journal Cell Report on the 7th reporting that the HIV now can also soon show resistance response to the popular "gene scissors" therapy, but this therapy is still expected to be improved to continue to be anti-AIDS.
Scientists discovered that bacteria can obtain partial DNA (deoxyribonucleic acid) fragment and integrate it into the genome to form memory after a virus infection. When invaded again by this time, bacteria will transcribe corresponding RNA (ribonucleic acid) and use the "location information" therein to guide the locating and cutting of Cas protein complexes, thus destroying the invading virus DNA.
In recent years, the popular "gene scissors" therapy - genome editing technology CRISPR just uses this principle, using a customized RNA to lead Cas9 enzyme which acts as a role of scissor responsible scissors effect. Scientists cut the DNA viruses imported by HIV into host cells according to presupposed sites, thus preventing the proliferation of HIV replication.
But according to these new reports, their experiments confirmed that HIV can escape under gene scissors rapidly. The sequencing of the genome with HIV escape indicates that this virus had changed the DNA target sequence identified by CRISPR technology.
Liang Chen pointed out that the appearance of HIV's escape or a "resistance" is not accident. What surprised them was that further analysis showed that the changes of HIV were mostly not caused by virus reverse transcriptase which was generally considered by the scientific community. He thought the changes happened when host cells were trying to restore the cracked DNA because of cutting after Cas9 enzyme cut the DNA of HIV. "In other words, the therapy also helps in the escape of the virus when inhibiting the proliferation of HIV."
The researchers proposed two improved schemes to treat AIDS using gene scissors: one is to attack multiple HIV genomic sites to increase the difficulty of escape for virus; the second one is to use scissors enzyme except Cas9.
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