ABSTRACT
Oncolytic viruses (OVs) are anti-cancer therapeutics combining the selective killing of cancer cells with the triggering of an anti-tumoral immune response. The latter effect can be improved by arming OVs with immunomodulatory factors. Due to the heterogeneity of cancer and the tumor microenvironment, it is anticipated that strategies based on the co-expression of multiple therapeutic molecules that interfere with different features of the target malignancy will be more effective than mono-therapies. Here, we show that (i) the simultaneous expression of different proteins in triple-negative breast cancer (TNBC) cells can be achieved through their infection with a combination of OVs based on herpes simplex virus type 1 (oHSV1), each encoding a single transgene. (ii) The level of expressed proteins is dependent on the number of infectious viral particles utilized to challenge tumor cells. (iii) All recombinant viruses exhibited comparable efficacy in the killing of TNBC cells in single and multiple infections and showed similar kinetics of replication. Overall, our results suggest that a strategy based on co-infection with a panel of oHSV1s may represent a promising combinatorial therapeutic approach for TNBC, as well as for other types of solid tumors, that merits further investigation in more advanced in vitro and in vivo models.
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BACKGROUND & AIMS: The underlying mechanisms and clinical impact of portal microthrombosis in severe COVID-19 are unknown. Intrapulmonary vascular dilation (IPVD)-related hypoxia has been described in severe liver diseases. We hypothesised that portal microthrombosis is associated with IPVD and fatal respiratory failure in COVID-19. METHODS: Ninety-three patients who died from COVID-19 were analysed for portal microvascular damage (histology), IPVD (histology and chest-computed tomography, CT), and hypoxemia (arterial blood gas). Seventeen patients who died from COVID-19-unrelated pneumonia served as controls. Vascular lesions and microthrombi were phenotyped for endothelial (vWF) and pericyte (αSMA/PDGFR-ß) markers, tissue factor (TF), viral spike protein and nucleoprotein (SP, NP), fibrinogen, and platelets (CD41a). Viral particles in vascular cells were assessed by transmission electron microscopy. Cultured pericytes were infected with SARS-CoV-2 to measure TF expression and tubulisation of human pulmonary microvascular endothelial cells was assessed upon vWF treatment. RESULTS: IPVD was present in 16/66 patients with COVID-19, with available liver and lung histology, and was associated with younger age (62 vs. 78 years-old), longer illness (25 vs. 14 days), worsening hypoxemia (PaO2/FiO2 from 209 to 89), and an increased requirement for ventilatory support (63% vs. 22%) compared to COVID-19/Non-IPVD. IPVD, absent in controls, was confirmed by chest CT. COVID-19/IPVD liver histology showed portal microthrombosis in >82.5% of portal areas, with a thicker wall of αSMA/PDGFR-ß+/SP+/NP+ pericytes compared with COVID-19/Non-IPVD. Thrombosed portal venules correlated with αSMA+ area, whereas infected SP+/NP+ pericytes expressed TF. SARS-CoV-2 viral particles were observed in portal pericytes. In vitro SARS-CoV-2 infection of pericytes upregulated TF and induced endothelial cells to overexpress vWF, which expanded human pulmonary microvascular endothelial cell tubules. CONCLUSIONS: SARS-CoV-2 infection of liver pericytes elicits a local procoagulant response associated with extensive portal microthrombosis, IPVD and worsening respiratory failure in fatal COVID-19. IMPACT AND IMPLICATIONS: Vascular involvement of the liver represents a serious complication of COVID-19 infection that must be considered in the work-up of patients with long-lasting and progressively worsening respiratory failure, as it may associate with the development of intrapulmonary vascular dilations. This clinical picture is associated with a procoagulant phenotype of portal venule pericytes, which is induced by SARS-CoV-2 infection of pericytes. Both observations provide a model that may apply, at least in part, to other vascular disorders of the liver, featuring obliterative portal venopathy, similarly characterised at the clinical level by development of hypoxemia and at the histological level by phlebosclerosis and reduced calibre of the portal vein branches in the absence of cirrhosis. Moreover, our findings shed light on an overlooked player in the pathophysiology of thrombosis, i.e. pericytes, which may present a novel therapeutic target.
ABSTRACT
The chaos theory, a field of study in mathematics and physics, offers a unique lens through which to understand the dynamics of the COVID-19 pandemic. This theory, which deals with complex systems whose behavior is highly sensitive to initial conditions, can provide insights into the unpredictable and seemingly random nature of the pandemic's spread. In this review, we will discuss some literature data with the aim of showing how chaos theory could provide valuable perspectives in understanding the complex and dynamic nature of the COVID-19 pandemic. In particular, we will emphasize how the chaos theory can help in dissecting the unpredictable, non- linear progression of the disease, the importance of initial conditions, and the complex interactions between various factors influencing its spread. These insights are crucial for developing effective strategies to manage and mitigate the impact of the pandemic.
Subject(s)
COVID-19 , Nonlinear Dynamics , Humans , COVID-19/epidemiology , PandemicsABSTRACT
Human cytomegalovirus (HCMV) is the viral leading cause of congenital defects in newborns worldwide. Many aspects of congenital CMV (cCMV) infection, which currently lacks a specific treatment, as well as the main determinants of neuropathogenesis in the developing brain during HCMV infection are unclear. In this study, we modeled HCMV infection at different stages of neural development. Moreover, we evaluated the effects of both approved and investigational anti-HCMV drugs on viral replication and gene expression in two different neural progenitor cell lines, i.e., human embryonic stem cells-derived neural stem cells (NSCs) and fetus-derived neuroepithelial stem (NES) cells. Ganciclovir, letermovir, nitazoxanide, and the ozonide OZ418 reduced viral DNA synthesis and the production of infectious virus in both lines of neural progenitors. HCMV infection dysregulated the expression of genes that either are markers of neural progenitors, such as SOX2, NESTIN, PAX-6, or play a role in neurogenesis, such as Doublecortin. Treatment with antiviral drugs had different effects on HCMV-induced dysregulation of the genes under investigation. This study contributes to the understanding of the molecular mechanisms of cCMV neuropathogenesis and paves the way for further consideration of anti-HCMV drugs as candidate therapeutic agents for the amelioration of cCMV-associated neurological manifestations.
Subject(s)
Cytomegalovirus Infections , Cytomegalovirus , Infant, Newborn , Humans , Cytomegalovirus Infections/drug therapy , Brain , Drugs, Investigational , Stem Cells , Antiviral Agents/pharmacologyABSTRACT
Here we propose that viruses emerging in the human population undergo an evolution that is conditioned by the rules of chaos. Our data support the notion that the initial growth rate "r" affects the chances of the virus to establish a long-lasting relationship with the new host. Indeed, an emerging virus is able to spread and adapt only when it displays an initial r falling in a range frankly associated with chaotic growth.
Subject(s)
Coronavirus Infections , Coronavirus , Selection, Genetic , Humans , Coronavirus/geneticsABSTRACT
Background: Comparative data on mortality in COVID-19 patients treated with molnupiravir or with nirmatrelvir plus ritonavir are inconclusive. We therefore compared all-cause mortality in community-dwelling COVID-19 patients treated with these drugs during the Omicron era. Methods: Data collected in the nationwide, population-based, cohort of patients registered in the database of the Italian Medicines Agency (AIFA) were used. To increase completeness of the recorded deaths and date correctness, a cross-check with the National Death Registry provided by the Ministry of the Interior was performed. We included in this study all patients infected by SARS-CoV-2 treated within 5 days after the test date and symptom onset between February 8 and April 30, 2022. All-cause mortalities by day 28 were compared between the two treatment groups after balancing for baseline characteristics using weights obtained from a gradient boosting machine algorithm. Findings: In the considered timeframe, 17,977 patients treated with molnupiravir and 11,576 patients with nirmatrelvir plus ritonavir were included in the analysis. Most patients (25,617/29,553 = 86.7%) received a full vaccine course including the booster dose. A higher crude incidence rate of all-cause mortality was found among molnupiravir users (51.83 per 100,000 person-days), compared to nirmatrelvir plus ritonavir users (22.29 per 100,000 person-days). However, molnupiravir-treated patients were older than those treated with nirmatrelvir plus ritonavir and differences between the two populations were found as far as types of co-morbidities were concerned. For this reason, we compared the weight-adjusted cumulative incidences using the Aalen estimator and found that the adjusted cumulative incidence rates were 1.23% (95% CI 1.07%-1.38%) for molnupiravir-treated and 0.78% (95% CI 0.58%-0.98%) for nirmatrelvir plus ritonavir-treated patients (adjusted log rank p = 0.0002). Moreover, the weight-adjusted mixed-effect Cox model including Italian regions and NHS centers as random effects and treatment as the only covariate confirmed a significant reduced risk of death in patients treated with nirmatrelvir plus ritonavir. Lastly, a significant reduction in the risk of death associated with nirmatrelvir plus ritonavir was confirmed in patient subgroups, such as in females, fully vaccinated patients, those treated within day 2 since symptom onset and patients without (haemato)-oncological diseases. Interpretation: Early initiation of nirmatrelvir plus ritonavir was associated for the first time with a significantly reduced risk of all-cause mortality by day 28 compared to molnupiravir, both in the overall population and in patient subgroups, including those fully vaccinated with the booster dose. Funding: This study did not receive funding.
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Oncolytic viruses (OVs) are promising therapeutics for tumors with a poor prognosis. An OV based on herpes simplex virus type 1 (oHSV-1), talimogene laherparepvec (T-VEC), has been recently approved by the Food and Drug Administration (FDA) and by the European Medicines Agency (EMA) for the treatment of unresectable melanoma. T-VEC, like most OVs, is administered via intratumoral injection, underlining the unresolved problem of the systemic delivery of the oncolytic agent for the treatment of metastases and deep-seated tumors. To address this drawback, cells with a tropism for tumors can be loaded ex vivo with OVs and used as carriers for systemic oncolytic virotherapy. Here, we evaluated human monocytes as carrier cells for a prototype oHSV-1 with a similar genetic backbone as T-VEC. Many tumors specifically recruit monocytes from the bloodstream, and autologous monocytes can be obtained from peripheral blood. We demonstrate here that oHSV-1-loaded primary human monocytes migrated in vitro towards epithelial cancer cells of different origin. Moreover, human monocytic leukemia cells selectively delivered oHSV-1 to human head-and-neck xenograft tumors grown on the chorioallantoic membrane (CAM) of fertilized chicken eggs after intravascular injection. Thus, our work shows that monocytes are promising carriers for the delivery of oHSV-1s in vivo, deserving further investigation in animal models.
Subject(s)
Herpesvirus 1, Human , Melanoma , Oncolytic Virotherapy , Oncolytic Viruses , Chick Embryo , Animals , Humans , Herpesvirus 1, Human/genetics , Melanoma/therapy , Chickens , Monocytes , Chorioallantoic Membrane , Oncolytic Viruses/geneticsABSTRACT
Our hypothesis about evolution of the COVID-19 pandemic foresees an inverse relation between infectivity (R0) and lethality (L) of SARS-CoV-2. The above parameters are driven by a continuing mutation process granting the virus a clear survival advantage over virulence. For interpreting this relation we adopted a simple equation, R0 × L ≈ k, by which R0 and L depend upon a constant k, that corresponds to an intrinsic property of the viral species involved. The hypothesis was verified by following changes of the R0 and L terms of the formula in the different variants of SARS-CoV-2 that progressively appeared. A further validation came when the equation was applied to pandemic and epidemic influenza type A viruses, Ebola virus and measles virus. We believe this equation that considers virus biology in Darwinian terms could be extremely useful to better face infectious viral threats and validate virus-host molecular interactions relevant to viral pathogenesis.
ABSTRACT
Several hypotheses have been presented on the origin of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) from its identification as the agent causing the current coronavirus disease 19 (COVID-19) pandemic. So far, no solid evidence has been found to support any hypothesis on the origin of this virus, and the issue continue to resurface over and over again. Here we have unfolded a pattern of distribution of several mutations in the SARS-CoV-2 proteins in 24 geo-locations across different continents. The results showed an evenly uneven distribution of the unique protein variants, distinct mutations, unique frequency of common conserved residues, and mutational residues across these 24 geo-locations. Furthermore, ample mutations were identified in the evolutionarily conserved invariant regions in the SARS-CoV-2 proteins across almost all geo-locations studied. This pattern of mutations potentially breaches the law of evolutionary conserved functional units of the beta-coronavirus genus. These mutations may lead to several novel SARS-CoV-2 variants with a high degree of transmissibility and virulence. A thorough investigation on the origin and characteristics of SARS-CoV-2 needs to be conducted in the interest of science and for the preparation of meeting the challenges of potential future pandemics.
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , SARS-CoV-2/genetics , COVID-19/genetics , Pandemics , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/chemistry , MutationABSTRACT
Remdesivir is the first drug approved for treatment of COVID-19 but current evidence for recommending its use for the treatment of moderate-to-severe disease is still controversial among clinical guidelines. We performed a nationwide, registry-based study including all Italian hospitalized patients with COVID-19 treated with remdesivir to assess the impact of major confounders on crude 15-day and 29-day mortality. Mortality was calculated using the Kaplan-Meier estimator and the Cox proportional-hazards model was applied to analyze the risks by patient's baseline features. In total, 16,462 patients treated with remdesivir from 29 October 2020 to 17 December 2020 were entered in the study. Crude 15-day and 29-day mortality were 7.1% (95% CI, 6.7-7.5%) and 11.7% (95% CI, 11.2-12.2%), respectively. Being treated within two days of admission reduced the risk of death by about 40% (HR 1.4, 95% CI, 1.2-1.6). Results from the largest cohort of remdesivir-treated patients suggests that mortality in SARS-CoV-2 hospitalized patients is substantially influenced by the days between SARS-CoV-2 diagnosis and drug prescription. Current recommendations and future clinical trials for remdesivir alone or in combination should carefully consider the target population and timing for best efficacy of treatment.
Subject(s)
COVID-19 Drug Treatment , SARS-CoV-2 , Adenosine Monophosphate/analogs & derivatives , Alanine/analogs & derivatives , Antiviral Agents/therapeutic use , COVID-19 Testing , Humans , Italy/epidemiology , RegistriesABSTRACT
Adult vaccination programs are receiving increasing attention however, little is known regarding the impact of age on the maintenance of the immune response. We investigated this issue in the context of a human papillomavirus (HPV) vaccination program collecting real-world data on the durability of humoral immunity in 315 female subjects stratified according to vaccination age (adolescents and adults) and sampled at early or late time points after the last vaccine dose. HPV-specific IgGs, but not memory B cells, were induced and maintained at higher levels in subjects vaccinated during adolescence. Nonetheless, antibody functions waned over time to a similar degree in adolescents and adults. To shed light on this phenomena, we analyzed quantitative and qualitative properties of lymphocytes. Similar biochemical features were observed between B-cell subsets from individuals belonging to the two age groups. Long term humoral responses toward vaccines administered at an earlier age were comparably maintained between adolescents and adults. The percentages of naïve B and CD4+ T cells were significantly higher in adolescents, and the latter directly correlated with IgG titers against 3 out of 4 HPV types. Our results indicate that age-specific HPV vaccine responsiveness is mostly due to quantitative differences of immune cell precursors rather than qualitative defects in B cells. In addition, our results indicate that adults also have a good humoral immunogenic profile, suggesting that their inclusion in catch-up programmes is desirable.
ABSTRACT
Open reading frame 8 (ORF8) shows one of the highest levels of variability among accessory proteins in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus Disease 2019 (COVID-19). It was previously reported that the ORF8 protein inhibits the presentation of viral antigens by the major histocompatibility complex class I (MHC-I), which interacts with host factors involved in pulmonary inflammation. The ORF8 protein assists SARS-CoV-2 in evading immunity and plays a role in SARS-CoV-2 replication. Among many contributing mutations, Q27STOP, a mutation in the ORF8 protein, defines the B.1.1.7 lineage of SARS-CoV-2, engendering the second wave of COVID-19. In the present study, 47 unique truncated ORF8 proteins (T-ORF8) with the Q27STOP mutations were identified among 49,055 available B.1.1.7 SARS-CoV-2 sequences. The results show that only one of the 47 T-ORF8 variants spread to over 57 geo-locations in North America, and other continents, which include Africa, Asia, Europe and South America. Based on various quantitative features, such as amino acid homology, polar/non-polar sequence homology, Shannon entropy conservation, and other physicochemical properties of all specific 47 T-ORF8 protein variants, nine possible T-ORF8 unique variants were defined. The question as to whether T-ORF8 variants function similarly to the wild type ORF8 is yet to be investigated. A positive response to the question could exacerbate future COVID-19 waves, necessitating severe containment measures.
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , SARS-CoV-2/genetics , COVID-19/epidemiology , Open Reading Frames/genetics , Antigens, Viral/geneticsABSTRACT
The coronavirus disease 2019 (COVID-19) is caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS- CoV-2) with an estimated fatality rate of less than 1%. The SARS-CoV-2 accessory proteins ORF3a, ORF6, ORF7a, ORF7b, ORF8, and ORF10 possess putative functions to manipulate host immune mechanisms. These involve interferons, which appear as a consensus function, immune signaling receptor NLRP3 (NLR family pyrin domain-containing 3) inflammasome, and inflammatory cytokines such as interleukin 1ß (IL-1ß) and are critical in COVID-19 pathology. Outspread variations of each of the six accessory proteins were observed across six continents of all complete SARS-CoV-2 proteomes based on the data reported before November 2020. A decreasing order of percentage of unique variations in the accessory proteins was determined as ORF3a > ORF8 > ORF7a > ORF6 > ORF10 > ORF7b across all continents. The highest and lowest unique variations of ORF3a were observed in South America and Oceania, respectively. These findings suggest that the wide variations in accessory proteins seem to affect the pathogenicity of SARS-CoV-2.
Subject(s)
COVID-19/virology , SARS-CoV-2/genetics , Viral Proteins/genetics , Viroporin Proteins/genetics , COVID-19/pathology , Genetic Variation , Humans , Phylogeny , SARS-CoV-2/pathogenicityABSTRACT
The devastating impact of the ongoing coronavirus disease 2019 (COVID-19) on public health, caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has made targeting the COVID-19 pandemic a top priority in medical research and pharmaceutical development. Surveillance of SARS-CoV-2 mutations is essential for the comprehension of SARS-CoV-2 variant diversity and their impact on virulence and pathogenicity. The SARS-CoV-2 open reading frame 10 (ORF10) protein interacts with multiple human proteins CUL2, ELOB, ELOC, MAP7D1, PPT1, RBX1, THTPA, TIMM8B, and ZYG11B expressed in lung tissue. Mutations and co-occurring mutations in the emerging SARS-CoV-2 ORF10 variants are expected to impact the severity of the virus and its associated consequences. In this article, we highlight 128 single mutations and 35 co-occurring mutations in the unique SARS-CoV-2 ORF10 variants. The possible predicted effects of these mutations and co-occurring mutations on the secondary structure of ORF10 variants and host protein interactomes are presented. The findings highlight the possible effects of mutations and co-occurring mutations on the emerging 140 ORF10 unique variants from secondary structure and intrinsic protein disorder perspectives.
Subject(s)
COVID-19/virology , Host Microbial Interactions/immunology , Open Reading Frames , SARS-CoV-2/genetics , Viral Proteins , Humans , Mutation , Viral Proteins/genetics , Viral Proteins/immunologyABSTRACT
Various lineages of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have contributed to prolongation of the Coronavirus Disease 2019 (COVID-19) pandemic. Several non-synonymous mutations in SARS-CoV-2 proteins have generated multiple SARS-CoV-2 variants. In our previous report, we have shown that an evenly uneven distribution of unique protein variants of SARS-CoV-2 is geo-location or demography-specific. However, the correlation between the demographic transmutability of the SARS-CoV-2 infection and mutations in various proteins remains unknown due to hidden symmetry/asymmetry in the occurrence of mutations. This study tracked how these mutations are emerging in SARS-CoV-2 proteins in six model countries and globally. In a geo-location, considering the mutations having a frequency of detection of at least 500 in each SARS-CoV-2 protein, we studied the country-wise percentage of invariant residues. Our data revealed that since October 2020, highly frequent mutations in SARS-CoV-2 have been observed mostly in the Open Reading Frame (ORF) 7b and ORF8, worldwide. No such highly frequent mutations in any of the SARS-CoV-2 proteins were found in the UK, India, and Brazil, which does not correlate with the degree of transmissibility of the virus in India and Brazil. However, we have found a signature that SARS-CoV-2 proteins were evolving at a higher rate, and considering global data, mutations are detected in the majority of the available amino acid locations. Fractal analysis of each protein's normalized factor time series showed a periodically aperiodic emergence of dominant variants for SARS-CoV-2 protein mutations across different countries. It was noticed that certain high-frequency variants have emerged in the last couple of months, and thus the emerging SARS-CoV-2 strains are expected to contain prevalent mutations in the ORF3a, membrane, and ORF8 proteins. In contrast to other beta-coronaviruses, SARS-CoV-2 variants have rapidly emerged based on demographically dependent mutations. Characterization of the periodically aperiodic nature of the demographic spread of SARS-CoV-2 variants in various countries can contribute to the identification of the origin of SARS-CoV-2.
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Mutation , UncertaintyABSTRACT
Among numerous point mutation differences between the SARS-CoV-2 and the bat RaTG13 coronavirus, only the 12-nucleotide furin cleavage site (FCS) exceeds 3 nucleotides. A BLAST search revealed that a 19 nucleotide portion of the SARS.Cov2 genome encompassing the furing cleavage site is a 100% complementary match to a codon-optimized proprietary sequence that is the reverse complement of the human mutS homolog (MSH3). The reverse complement sequence present in SARS-CoV-2 may occur randomly but other possibilities must be considered. Recombination in an intermediate host is an unlikely explanation. Single stranded RNA viruses such as SARS-CoV-2 utilize negative strand RNA templates in infected cells, which might lead through copy choice recombination with a negative sense SARS-CoV-2 RNA to the integration of the MSH3 negative strand, including the FCS, into the viral genome. In any case, the presence of the 19-nucleotide long RNA sequence including the FCS with 100% identity to the reverse complement of the MSH3 mRNA is highly unusual and requires further investigations.
ABSTRACT
One of the main pathological features of Parkinson's disease (PD) is a diffuse accumulation of alpha-synuclein (aS) aggregates in neurons. The NEDD4 E3 Ub ligase promotes aS degradation by the endosomal-lysosomal route. Interestingly, NEDD4, as well as being a small molecule able to trigger its functions, is protective against human aS toxicity in evolutionary distant models. While pharmacological activation of E3 enzymes is not easy to achieve, their flexibility and the lack of "consensus" motifs for Ub-conjugation allow the development of engineered Ub-ligases, able to target proteins of interest. We developed lentiviral vectors, encoding well-characterized anti-human aS scFvs fused in frame to the NEDD4 catalytic domain (ubiquibodies), in order to target ubiquitinate aS. We demonstrate that, while all generated ubiquibodies bind to and ubiquitinate aS, the one directed against the non-amyloid component (NAC) of aS (Nac32HECT) affects aS's intracellular levels. Furthermore, Nac32HECT expression partially rescues aS's overexpression or mutation toxicity in neural stem cells. Overall, our data suggest that ubiquibodies, and Nac32HECT in particular, represent a valid platform for interfering with the effects of aS's accumulation and aggregation in neurons.
Subject(s)
Genetic Vectors/metabolism , Lentivirus/genetics , Nedd4 Ubiquitin Protein Ligases/metabolism , Recombinant Proteins/metabolism , alpha-Synuclein/metabolism , Animals , Cell Line, Tumor , Dopaminergic Neurons/metabolism , HEK293 Cells , Humans , Intracellular Space/metabolism , Mice , Neural Stem Cells/metabolism , Parkinson Disease/pathology , UbiquitinationABSTRACT
Crimean-Congo hemorrhagic fever (CCHF) is a severe disease of humans caused by CCHF virus (CCHFV), a biosafety level (BSL)-4 pathogen. Ticks of the genus Hyalomma are the viral reservoir, and they represent the main vector transmitting the virus to its hosts during blood feeding. We have previously shown that CCHFV can persistently infect Hyalomma-derived tick cell lines. However, the mechanism allowing the establishment of persistent viral infections in ticks is still unknown. Hazara virus (HAZV) can be used as a BSL-2 model virus instead of CCHFV to study virus/vector interactions. To investigate the mechanism behind the establishment of a persistent infection, we developed an in vitro model with Hyalomma-derived tick cell lines and HAZV. As expected, HAZV, like CCHFV, persistently infects tick cells without any sign of cytopathic effect, and the infected cells can be cultured for more than 3 years. Most interestingly, we demonstrated the presence of short viral-derived DNA forms (vDNAs) after HAZV infection. Furthermore, we demonstrated that the antiretroviral drug azidothymine triphosphate could inhibit the production of vDNAs, suggesting that vDNAs are produced by an endogenous retrotranscriptase activity in tick cells. Moreover, we collected evidence that vDNAs are continuously synthesized, thereby downregulating viral replication to promote cell survival. Finally, vDNAs were also detected in CCHFV-infected tick cells. In conclusion, vDNA synthesis might represent a strategy to control the replication of RNA viruses in ticks allowing their persistent infection. IMPORTANCE Crimean-Congo hemorrhagic fever (CCHF) is an emerging tick-borne viral disease caused by CCHF virus (CCHFV). Ticks of the genus Hyalomma can be persistently infected with CCHFV representing the viral reservoir, and the main vector for viral transmission. Here we showed that tick cells infected with Hazara virus, a nonpathogenic model virus closely related to CCHFV, contained short viral-derived DNA forms (vDNAs) produced by endogenous retrotranscriptase activity. vDNAs are transitory molecules requiring viral RNA replication for their continuous synthesis. Interestingly, vDNA synthesis seemed to be correlated with downregulation of viral replication and promotion of tick cell viability. We also detected vDNAs in CCHFV-infected tick cells suggesting that they could represent a key element in the cell response to nairovirus infection and might represent a more general mechanism of innate immunity against RNA viral infection.
Subject(s)
DNA, Viral/metabolism , Hemorrhagic Fever Virus, Crimean-Congo/genetics , Nairovirus/genetics , Ticks/virology , Virus Replication/genetics , Animals , Cell Line , DNA, Viral/genetics , Phylogeny , RNA, Viral/genetics , Ticks/cytologyABSTRACT
The spike (S) protein is a critical determinant of the infectivity and antigenicity of SARS-CoV-2. Several mutations in the S protein of SARS-CoV-2 have already been detected, and their effect in immune system evasion and enhanced transmission as a cause of increased morbidity and mortality are being investigated. From pathogenic and epidemiological perspectives, S proteins are of prime interest to researchers. This study focused on the unique variants of S proteins from six continents: Asia, Africa, Europe, Oceania, South America, and North America. In comparison to the other five continents, Africa had the highest percentage of unique S proteins (29.1%). The phylogenetic relationship implies that unique S proteins from North America are significantly different from those of the other five continents. They are most likely to spread to the other geographic locations through international travel or naturally by emerging mutations. It is suggested that restriction of international travel should be considered, and massive vaccination as an utmost measure to combat the spread of the COVID-19 pandemic. It is also further suggested that the efficacy of existing vaccines and future vaccine development must be reviewed with careful scrutiny, and if needed, further re-engineered based on requirements dictated by new emerging S protein variants.
Subject(s)
COVID-19/epidemiology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Amino Acid Substitution/immunology , COVID-19/immunology , Entropy , Humans , Isoelectric Point , Mutation/immunology , Pandemics/statistics & numerical data , Phylogeny , Spike Glycoprotein, Coronavirus/immunologyABSTRACT
Although vaccination represents the most promising way to stop or contain the coronavirus disease 2019 (COVID-19) pandemic and safety and effectiveness of available vaccines were proven, a small number of individuals who received anti-SARS-CoV-2 vaccines developed a prothrombotic syndrome. Vaccine-induced immune thrombotic thrombocytopenia (VITT) can be triggered by the adenoviral vector-based vaccine, whereas lipid nanoparticle-mRNA-based vaccines can induce rare cases of deep vein thrombosis (DVT). Although the main pathogenic mechanisms behind this rare phenomenon have not yet been identified, both host and vaccine factors might be involved, with pathology at least in part being related to the vaccine-triggered autoimmune reaction. In this review, we are considering some aspects related to pathogenesis, major risk factors, as well as peculiarities of diagnosis and treatment of this rare condition.