Stealth virus treatment

A stealth virus is a hidden computer virus that attacks operating system processes and averts typical anti-virus or anti-malware scans. Stealth viruses hide in files, partitions and boot sectors and are adept at deliberately avoiding detection.

Stealth virus eradication requires advanced anti-virus software or a clean system reboot. Stealth viruses hide altered computer data and other harmful control functions in system memory and self-copy to undetectable computer areas, effectively tricking anti-virus software.

In order to avoid detection, stealth viruses also self-modify in the following ways:. By: Brad Rudisail Contributor. By: Kaushik Pal Contributor. By: Leah Zitter Contributor. Next, mice in the relevant groups received mIU of anti-MeV IgG antibody intraperitoneally three hours before virus treatment via the same route.

Ns, no significant; nd, not done. Our findings are consistent with the hypothesis that CD46 tropism governs the efficacy of MeV virotherapy [ 6 , 31 , 32 ]. Finally, MeV-Stealth was oncolytic, its in vivo potency was not impacted by measles-immune serum. Collectively, this experimental evidence strongly supports the overall concept that antibody-mediated CD46 targeting of MeV through wild-type CDV envelope proteins is an effective way to circumvent neutralization of oncolytic MeVs.

One of the major obstacles to the production of recombinant MeV carrying foreign glycoproteins is related to the necessity of proper trafficking and assembly of all the viral components [ 20 , 33 ]. We and others have previously reported that the envelope of the CDV OL strain is fully interchangeable with that of MeV [ 11 , 14 , 16 ].

However, Rouxel et al. Since the fusogenic activity of envelope glycoproteins is another key determinant for the generation of replication-competent MeV [ 34 ], we sought to enhance the fusion activity of the wild-type CDV envelope to levels similar to those of the OL envelope.

Until now, similar results have been documented only across the genus Henipavirus , including Nipah virus, Hendra virus and Ghana virus [ 24 , 35 , 36 ]. However, no previous studies accounted for the different cognate receptors of Nipah virus and CDV on the cell lines used [ 36 , 37 ]. The overexpression of CD46 in many different human cancers makes it a reasonable target of OVs and antibody-drug conjugated therapies [ 38 — 40 ].

We have previously established that cell lysis induced by MeV glycoproteins occurred only above a certain CD46 surface expression threshold, confirming the tumor selectivity of the virus [ 6 , 31 ].

Thus, our findings establish the basis for increasing tumor selectivity through the use of affinity-tuned scFvs. Indeed, toxicities observed with chimeric antigen receptor CAR T cell therapies have been ameliorated through the use of low-affinity scFvs against targets [ 44 , 45 ]. Since CD46 is expressed by all nucleated human cells, the use of low-affinity CDspecific scFvs might also alleviate safety concerns when moving into clinical trials.

In contrast to wild-type CDV strains, MeV-Stealth appears to be relatively resistant to adaptation to the use of alternate cell surface receptors. Pseudotyping approaches using foreign envelopes from viruses with unknown tropism limit the transition from bench to bedside due to the difficulty of studying the zoonotic potential of the pseudotyped products [ 16 , 20 ]; therefore, envelopes with known tropism, whether in humans or animals, are preferred [ 21 , 46 , 47 ].

Indeed, while MeV genetic diversity has decreased over time, new genetic lineages of CDV are frequently discovered [ 50 , 51 ]. Finally, the envelopes developed here have implications for improving gene and cell therapies. Similarly, arming adenovirus and herpes simplex virus strains with the MeV envelope glycoproteins enhances their cytotoxicity to tumor xenografts, likely via cell fusion-induced immunogenic cell death [ 22 , 54 — 56 ]. We expect that the new envelope generated here will be easily applicable to the aforementioned virus vectors to advance their in vivo applicability in MeV-immune individuals.

One of the weaknesses of this study was our inability to examine the immunotherapeutic phase of MeV virotherapy due to the lack of reliable immunocompetent models. Mouse cells do not allow MeV replication [ 57 ], and our observations in SCID and athymic nude mice accounted for only direct viral oncolysis.

However, based on the existing literature on Newcastle Disease virus [ 58 ], reovirus [ 59 ], herpes simplex virus [ 60 ], and Maraba virus [ 61 ], we anticipate a synergistic effect of MeV-Stealth treatment in MeV-immunized mice due to cross-reactive T-cell responses between MeV and CDV [ 14 , 62 , 63 ].

A second weakness of the study relates to the mechanism of antibody mediated protection against measles. Here we focused exclusively on direct virus neutralization due to the good correlation between antibody titers, as determined by virus neutralization assay, and protection from measles [ 64 — 66 ]. Thus, we did not evaluate alternative mechanisms of antibody mediated protection such as antibody-dependent complement-mediated cytolysis and antibody-dependent cellular-mediated cytotoxicity ADCC [ 67 — 69 ].

In summary, the data presented in this manuscript indicate that substitution of the MeV envelope glycoproteins by CDtargeted CDV envelope glycoproteins is an alternative strategy to circumvent the inhibition of MeV-immune serum and achieve oncolysis in multiple myeloma and ovarian cancer models.

Future use of CDV envelopes displaying affinity-tuned CD46 binding domains might facilitate the development of Stealth platforms for clinical studies by sparing noncancerous human cells with basal levels of CD H1-HeLa Cat.

HT cells obtained from Dr. Vero African green monkey kidney cells Vero, Cat. B1 kindly provided to us by Dr. The primers contained the PacI and SpeI restriction sites underlined as well as the coding sequence for the untranslated region of MeV-H italics.

The culture supernatants containing the recombinant proteins were collected and passed through a Protein G chromatography cartridge Cat. Bound recombinant proteins were eluted with 0. Protein concentrations were calculated from the protein extinction coefficient as determined from the amino acid composition. For a quantitative fusion assay, a dual-split reporter system [ 81 , 82 ] was used as described elsewhere [ 14 ], using BHK cells as the effector cells.

For semiquantitative assessment of fusion, Vero cells and derivative cell lines were transfected with a total of 0. Images were obtained with a microscope Eclipse Ti-S; Nikon at 40x or x magnification. MA, Thermo Fisher Scientific , as described elsewhere [ 14 , 83 ]. The rest was incubated with 0. IB, Thermo Fisher Scientific. Representative results of two independent repeats are shown. A, Sigma-Aldrich. In parallel, ng of scFv-Fc fusion protein was first bound to wells, and protein levels were monitored by measuring the optical density OD nm after incubation with the secondary antibody alone.

After s of buffer wash and a s stabilization period, CD46 concentration range 50 nM- 1, nM for A09, The association phase was followed by a s dissociation period followed by a 60 s injection of 10 mM glycine pH 2. All sensograms were fitted with a binding model using the Biacore T evaluation software v2.

When using eGFP-expressing viruses, fluorescence microscopy photographs were taken 48 hours post-infection. For infections with Fluc-expressing viruses, luciferase expression was measured using an Infinite M Pro multimode microplate reader Tecan Trading AG after adding 0. For virus growth kinetic analysis, Vero cells and derivative cell lines seeded in 6-well plates 16—18 h prior to infection were infected at a MOI of 0.

A fluorescence-based plaque reduction microneutralization PRMN assay was carried out as previously described [ 14 , 87 ]. The data were plotted as the log dilution of serum vs. Pooled human serum from 60—80 donors that had blood type AB Cat.

To establish subcutaneous tumors, 6-week-old female severe combined immunodeficiency SCID mice were injected in the right flank with 1 x 10 7 U B1 tumor cells. When the tumor reached 0. Tumor diameter was measured every other day, and tumor volume was calculated with the formula length x length x width x 0.

To establish an orthotopic model of ovarian cancer, 5x 10 6 SKOV3ip. Ten days later, the animals received mIU of measles-immune serum Cat. For the therapy experiment, 5x10 6 SKOV3ip. Statistical analyses were performed with GraphPad Prism 8. Survival data were analyzed using the Kaplan-Meier method, and the log-rank test was used to identify significant differences among groups. The accession numbers are indicated. B Protein expression of the attachment proteins and mutants on HEKT cells fixed with or without permeabilization analyzed by flow cytometry.

Histograms are from one representative experiment out of two biological replicates. Filled curves denote cells transfected with empty plasmids. The sequence surrounding the cleavage site in bold and that of the fusion peptide are shown. The numbering considers the homotypic signal peptides. Cells were stained at 16 hours posttransfection, and microphotographs were acquired for quantification.

C Quantification of syncytia formation. The luciferase signal was measured at 8 hours. The experiment was performed in technical duplicates. B Size exclusion chromatography trace for the CD46 used in the experiments. The estimated MW from a calibration curve is indicated. Detection was performed with the Fc portion used as a control for the amount of protein. Experiments were performed in technical duplicates.

For visualization purposes, an expression plasmid encoding eGFP was cotransfected, and eGFP autofluorescence was visualized at 24 hours posttransfection. Increased binding affinity to CD46 enhances CDspecific virus entry. Fluc-expressing Stealth viruses were used to infect the indicated cells at decreasing MOI.

Luciferase expression was measured 48h postinfection. Representative overlay of bright-field and fluorescence images were taken 48 hours post-infection. NA, not applicable i. Different MOI was used for visualization purposes. B Flow-cytometric analysis of the cell surface expression of MeV-receptors on B95m cells after incubation with PE-specific antibodies.

The determined number of molecules per cell is indicated in brackets. Scale bar, 1 mm. A Virus neutralization assay for MeV and Stealth.

The stealth virus can also avoid detection by concealing the size of the file it has infected. You can detect the virus by starting the system via a disk boot — to avoid systems the virus has control over — and then beginning an antivirus scan. However, even if detected here, there is a chance the virus has copied itself into another file on the system, so it remains a challenging virus to fully eradicate. In general, the best countermeasure is to use strong antivirus software designed to detect viruses and their hidden counterparts.

Industry definition for the term Stealth Virus. A stealth virus is complex malware that hides itself after infecting a computer. Will it also spark another wave of infections similar to the Delta variant? Do vaccinated people have any protection from the variant? As the world grapples with these questions, scientists are researching this new strain to understand the magnitude of the issue and its effect for the year The World Health Organization has said that it is too early to arrive at any conclusion.

Amid the dreaded uncertainty, here are the top 10 developments related to research on the Omicron variant:. Like us on Facebook and follow us on Twitter. Financial Express is now on Telegram. Click here to join our channel and stay updated with the latest Biz news and updates. SARS-CoV-2 Omicron Variant: Though most of the mutations in this stealth version are quite similar to that of the Omicron variant, there is a particular genetic code, which is missing in this version.