AAV8 transduction capacity is reduced by prior exposure to endosome-like pH conditions

Adeno-associated virus(AAV)is an essential instrument in the neuroscientist’s toolkit,which allows delivery of DNA to provide labeling with fluorescent proteins or genetic instructions to regulate gene expression.In the field of neural regeneration,the transduction of neurons enables the observation and regulation of axon growth and regeneration,and in the future will likely be a mechanism for delivering molecular therapies to promote sprouting and regeneration after central nervous system injury.Traditional formulations of AAV preparations permit efficient viral transduction under physiologic conditions,but an improved understanding of the mechanistic limitations of AAV transduction may facilitate production of more resilient AAV strains for investigative and therapeutic purposes.We studied AAV transduction in the context of prior exposure of AAV serotype 8(AAV8)to environmental pH within the range encountered during endosomal endocytosis(pH 7.4 to pH 4.4),during which low pH-triggered structural and autoproteolytic changes to the viral capsid are believed to be necessary for endosome escape and virus uncoating.Due to the fundamental nature of these processes,we hypothesized that premature exposure of AAV8 particles to acidic pH would decrease viral transduction of HT1080 cells in vitro,as measured by fluorescent reporter gene expression using high-content imaging analysis.We found that increasingly acidic incubation conditions were associated with concomitant reductions in transduction efficiency,and that quantitative levels of reporter gene expression in transduced cells were similarly decreased.The biggest decrease in transduction occurred between pH 7.4 and pH 6.4,suggesting the possible co-occurrence of a pH-associated event and viral inactivation within that range.Taken together,these findings indicate that exposure of AAV8 to acidic pH for as little as 1 hour is deleterious to transduction ability.Future studies are necessary to understand the pH-associated causative mechanisms involved.This study was approved by the University of Miami Institutional Animal Care and Use Committee,USA(Protocol#18-108-LF)on July 12,2018.

Sulfated liposome-based artificial cell membrane glycocalyx nanodecoys for coronavirus inactivation by membrane fusion

As a broad-spectrum antiviral nanoparticle,the cell membrane nanodecoy is a promising strategy for preventing viral infections.However,most of the cell membrane nanodecoys can only catch virus and cannot induce inactivation,which may bring about a considerably high risk of re-infection owing to the possible viral escape from the nanodecoys.To tackle this challenge,sulfated liposomes are employed to mimic the cell membrane glycocalyx for constructing an artificial cell membrane glycocalyx nanodecoy that exhibits excellent anti-coronavirus activity against HCoV-OC43,wild-type SARS-CoV-2,Alpha and Delta variant SARS-CoV-2 pseudovirus.In addition,this nanodecoy,loaded with surface sulfate groups as SARS-CoV-2 receptor arrays,can enhance the antiviral capability to virus inactivation through destroying the virus membrane structure and transfer the spike protein to postfusion conformation.Integrating bio-inspired recognition and inactivation of viruses in a single supramolecular entity,the artificial cell membrane nanodecoy opens a new avenue for the development of theranostic antiviral nanosystems,whose mass production is favored due to the facile engineering of sulfated liposomes.

Inhibitory effects of baicalein against herpes simplex virus type 1

Herpes simplex virus type 1(HSV-1)is a ubiquitous and widespread human pathogen,which gives rise to a range of diseases,including cold sores,corneal blindness,and encephalitis.Currently,the use of nucleoside analogs,such as acyclovir and penciclovir,in treating HSV-1 infection often presents limitation due to their side effects and low efficacy for drug-resistance strains.Therefore,new anti-herpetic drugs and strategies should be urgently developed.Here,we reported that baicalein,a naturally derived compound widely used in Asian countries,strongly inhibited HSV-1 replication in several models.Baicalein was effective against the replication of both HSV-1/F and HSV-1/Blue(an acyclovir-resistant strain)in vitro.In the ocular inoculation mice model,baicalein markedly reduced in vivo HSV-1/F replication,receded inflammatory storm and attenuated histological changes in the cornea.Consistently,baicalein was found to reduce the mortality of mice,viral loads both in nose and trigeminal ganglia in HSV-1 intranasal infection model.Moreover,an ex vivo HSV-1-EGFP infection model established in isolated murine epidermal sheets confirmed that baicalein suppressed HSV-1 replication.Further investigations unraveled that dual mechanisms,inactivating viral particles and inhibiting IκB kinase beta(IKK-β)phosphorylation,were involved in the anti-HSV-1 effect of baicalein.Collectively,our findings identified baicalein as a promising therapy candidate against the infection of HSV-1,especially acyclovir-resistant strain.