CRISPR/Cas9-mediated exploration and disruption of herpes simplex virus type 1

[NIETZSCHE_]

New (June 2019) results from Dutch researchers. 

https://www.narcis.nl/publication/RecordID/oai:dspace.library.uu.nl:1874%2F381246

"Herpesviruses can cause lifelong infections in almost 100% of the population. During infection, the virus can enter a "dormant" phase, also known as latency, in which it produces viral proteins to a very limited extent. This latent virus can therefore not be properly recognized by our immune system and as a result we are unable to clear these viruses from our body. There are no drugs available that can recognize and eliminate these dormant viruses. In this thesis, we try to eliminate herpesvirus infections with new techniques. We usurped an anti-viral system from bacteria: CRISPR/Cas9 to specifically inactivate genomes of human herpes viruses. This approach has proven to be highly effective at eliminating virus infections from various herpes viruses, including Epstein-Barr virus (EBV), human Herpes Simplex virus (HSV-1) and cytomegalovirus (CMV). When using multiple anti-herpesvirus CRISPR we were capable of fully blocking replication of HSV-1. In follow-up experiments we have compared the power of this new technique with the treatment method as it is used in the clinic for treatment against HSV-1. This showed that CRISPR/Cas9 was better able to combat HSV-1 infections and to reduce the formation of medication-avoiding mutants. These findings are important because it offers the possibility to further develop anti-HSV-1 CRISPR/Cas9 into a future treatment against HSV-1. Since the virus, in addition to cold sores, can cause recurring eye infections resulting in vision loss, a healing treatment could have a major medical and societal impact. In addition to directly inactivating viral genomes through CRISPR/Cas9, the technique can also be used to identify, host factors involved in the infection of a virus. Through large genome-wide screens, we found human genes that viruses use in the infection process. In addition to HSV-1, we performed a similar screen for the "MVA" smallpox virus and identified human genes used by the viruses in the infection process. The identification of such genes provides more insight into the interaction between host and virus, and can also provide tools for the targeted development of new treatment methods to prevent or treat virus infections in the future."

[Theremustbeaway]

I wonder why not hvs2 , sounds interesting.

[Cas9]

The U.S. company Excision Biotherapeutics plans on using Cas9 for hsv1 and CasY for hsv2. In both cases, their goal is to stop replication in the neuron. I don't know the exact process but as I understand it, no viral particles would emerge from the neuron. If successful, it would be a practical cure, The company's plans for when to start phase 1 have changed twice. They now plan on phase 1 starting in 2022 (hsv1) and 2023 (hsv2). Don't hold your breath.

To achieve a sterilizing cure, the latent virus must be eliminated. This of course is the ultimate. It is the latent virus that permanently remains in the neuron and periodically replicates, resulting in viral shedding and/or OBs.

Keith Jerome at Fred Hutch Research Center has concluded that enzymes like Cas9 etc... are too large to be effective in eliminating the latent virus. Dr Jerome has created his own meganuclease for destroying the latent virus. It is much smaller and consequently more effective than CRISPRCas9. The main issue in his research is delivery of this meganuclease to the nerve bundle infected with the virus. So far, he has been able to eliminate over 90% of the latent virus in certain ganglion but only 50% in other ganglion (because he needs to find the right AAV for delivery). He's working on it. Note that no one else has been able to destroy the latent virus. This is exciting news. There's a thread started by MikeHerp (a well informed and great guy) regarding Dr. Jerome's research.
https://honeycomb.click/topic/78072-great-news-dr-jerome-at-fred-hutch-has-achieved-50-to-90-elimination-of-latent-hsv-in-mice/#comments

[MikeHerp]

On 9/12/2019 at 11:23 AM, Cas9 said:

The U.S. company Excision Biotherapeutics plans on using Cas9 for hsv1 and CasY for hsv2. In both cases, their goal is to stop replication in the neuron. I don't know the exact process but as I understand it, no viral particles would emerge from the neuron. If successful, it would be a practical cure, The company's plans for when to start phase 1 have changed twice. They now plan on phase 1 starting in 2022 (hsv1) and 2023 (hsv2). Don't hold your breath.

To achieve a sterilizing cure, the latent virus must be eliminated. This of course is the ultimate. It is the latent virus that permanently remains in the neuron and periodically replicates, resulting in viral shedding and/or OBs.

Keith Jerome at Fred Hutch Research Center has concluded that enzymes like Cas9 etc... are too large to be effective in eliminating the latent virus. Dr Jerome has created his own meganuclease for destroying the latent virus. It is much smaller and consequently more effective than CRISPRCas9. The main issue in his research is delivery of this meganuclease to the nerve bundle infected with the virus. So far, he has been able to eliminate over 90% of the latent virus in certain ganglion but only 50% in other ganglion (because he needs to find the right AAV for delivery). He's working on it. Note that no one else has been able to destroy the latent virus. This is exciting news. There's a thread started by MikeHerp (a well informed and great guy) regarding Dr. Jerome's research.
https://honeycomb.click/topic/78072-great-news-dr-jerome-at-fred-hutch-has-achieved-50-to-90-elimination-of-latent-hsv-in-mice/#comments

Thanks @Cas9

[MikeHerp]

On 9/12/2019 at 12:17 AM, NIETZSCHE_ said:

New (June 2019) results from Dutch researchers. 

https://www.narcis.nl/publication/RecordID/oai:dspace.library.uu.nl:1874%2F381246

"Herpesviruses can cause lifelong infections in almost 100% of the population. During infection, the virus can enter a "dormant" phase, also known as latency, in which it produces viral proteins to a very limited extent. This latent virus can therefore not be properly recognized by our immune system and as a result we are unable to clear these viruses from our body. There are no drugs available that can recognize and eliminate these dormant viruses. In this thesis, we try to eliminate herpesvirus infections with new techniques. We usurped an anti-viral system from bacteria: CRISPR/Cas9 to specifically inactivate genomes of human herpes viruses. This approach has proven to be highly effective at eliminating virus infections from various herpes viruses, including Epstein-Barr virus (EBV), human Herpes Simplex virus (HSV-1) and cytomegalovirus (CMV). When using multiple anti-herpesvirus CRISPR we were capable of fully blocking replication of HSV-1. In follow-up experiments we have compared the power of this new technique with the treatment method as it is used in the clinic for treatment against HSV-1. This showed that CRISPR/Cas9 was better able to combat HSV-1 infections and to reduce the formation of medication-avoiding mutants. These findings are important because it offers the possibility to further develop anti-HSV-1 CRISPR/Cas9 into a future treatment against HSV-1. Since the virus, in addition to cold sores, can cause recurring eye infections resulting in vision loss, a healing treatment could have a major medical and societal impact. In addition to directly inactivating viral genomes through CRISPR/Cas9, the technique can also be used to identify, host factors involved in the infection of a virus. Through large genome-wide screens, we found human genes that viruses use in the infection process. In addition to HSV-1, we performed a similar screen for the "MVA" smallpox virus and identified human genes used by the viruses in the infection process. The identification of such genes provides more insight into the interaction between host and virus, and can also provide tools for the targeted development of new treatment methods to prevent or treat virus infections in the future."

This is good.  Thanks for sharing.  I was wondering what Van Diemen was up to since they published their paper a few years ago.  Seems like they are working on it, though the progress seems slow.  Still, it's encouraging to see other researchers are also focusing on this.  

They have confirmed that CRISPR Cas9 would be better as a treatment for HSV replication than existing meds.  That's good news.  But I question whether a treatment aimed only stopping replication would be approved as I don't know whether FDA or similar authority would approve gene scissors working perpetually in a human body.  

I understand that Jerome's team, intends to find a way to stop or remove the meganucleases after they are done snipping out latent virus.  I've even seen another research paper by other scientists which seemed to suggest that, meganucleases could be turned "off".  So it seems it may be possible.  

One other tidbit from this paper: "In addition to directly inactivating viral genomes through CRISPR/Cas9, the technique can also be used to identify, host factors involved in the infection of a virus."

This is an underrated aspect of gene editing, which will likely accelerate HSV cure research.  

[hk81]

On 10/13/2019 at 4:14 AM, MikeHerp said:

gene scissors working perpetually in a human body

Where are they saying that their therapy will operate in such a way? From this small extract, it looks like a regular CRISPR definitive treatment.

[MikeHerp]

It's just something I read a while ago.  I think Dr. Jerome talked about meganucleases possibly persisting for years in a human body.

I'm not sure how long CRISPR Cas0 can last.  But if CRISPR Cas9 can't last long, then it wouldn't he useful because CRISPR can't touch latent virus, unlike meganucleases.

So treatment that lasts only a few weeks and only stops replication without affecting latent virus, wouldn't be very helpful.