From symbiosis to independence: Investigating changes in the relationship between general practitioners' presence and pharmacies' market size in Slovakia

Using the Slovak pharmacy retail market case, this study examines the evolving interdependency between general practitioners (GPs) and pharmacies. Traditionally, they have operated symbiotically, with pharmacy revenues heavily reliant on prescriptions. However, the development of the market structures of these providers after the liberalization of the pharmacy retail market in 2005 raises a question about the stability of this relationship. By analyzing entry thresholds as a measure of the market size required for pharmacies to cover their entry costs, the study reveals that the dependency of pharmacies on the presence of GPs has diminished over time. In the initial year following the liberalization, the presence of a GP decreased the market size sufficient to cover entry costs for the first pharmacy by about 83% compared to a market without a GP. However, in 2019, this effect decreased to approximately 65%. This could imply worsened coverage of pharmaceutical services in small and rural areas with GPs as the entry decision of pharmacies is less elastic towards their presence.

Inhibition of porcine deltacoronavirus entry and replication by Cepharanthine

Porcine deltacoronavirus (PDCoV) is an emerging swine enteropathogenic coronavirus (CoV) that mainly causes acute diarrhea/vomiting, dehydration, and mortality in piglets, possessing economic losses and public health concerns. However, there are currently no proven effective antiviral agents against PDCoV. Cepharanthine (CEP) is a naturally occurring alkaloid used as a traditional remedy for radiation-induced symptoms, but its underlying mechanism of CEP against PDCoV has remained elusive. The aim of this study was to investigate the anti-PDCoV effects and mechanisms of CEP in LLC-PK1 cells. The results showed that the antiviral activity of CEP was based on direct action on cells, preventing the virus from attaching to host cells and virus replication. Importantly, Surface Plasmon Resonance (SPR) results showed that CEP has a moderate affinity to PDCoV receptor, porcine aminopeptidase N (pAPN) protein. AutoDock predicted that CEP can form hydrogen bonds with amino acid residues (R740, N783, and R790) in the binding regions of PDCoV and pAPN. In addition, RT-PCR results showed that CEP treatment could significantly reduce the transcription of ZBP1, cytokine (IL-1β and IFN-α) and chemokine genes (CCL-2, CCL-4, CCL-5, CXCL-2, CXCL-8, and CXCL-10) induced by PDCoV. Western blot analysis revealed that CEP could inhibit viral replication by inducing autophagy. In conclusion, our results suggest that the anti-PDCoV activity of CEP is not only relies on competing the virus binding with pAPN, but also affects the proliferation of the virus in vitro by downregulating the excessive immune response caused by the virus and inducing autophagy. CEP emerges as a promising candidate for potential anti-PDCoV therapeutic development.

Inhibition of dengue viruses by N-methylcytisine thio derivatives through targeting viral envelope protein and NS2B-NS3 protease

Dengue virus (DENV) is a significant global health threat, causing millions of cases worldwide each year. Developing antiviral drugs for DENV has been a challenging endeavor. Our previous study identified anti-DENV properties of two (-)-cytisine derivatives contained substitutions within the 2-pyridone core from a pool of 19 (-)-cytisine derivatives. This study aimed to expand on the previous research by investigating the antiviral potential of N-methylcytisine thio (mCy thio) derivatives against DENV, understanding the molecular mechanisms of antiviral activity for the active thio derivatives. The inhibitory assays on DENV-2-induced cytopathic effect and infectivity revealed that mCy thio derivatives 3 ((1R,5S)-3-methyl-1,2,3,4,5,6-hexahydro-8H-1,5-methanopyrido[1,2-a][1,5]diazocine-8-thione) and 6 ((1S,5R)-3-methyl-2-thioxo-1,2,3,4,5,6-hexahydro-8H-1,5-methanopyrido[1,2-a][1,5]diazocin-8-one) were identified as the active compounds against both DENV-1 and DENV-2. Derivative 6 displayed robust antiviral activity against DENV-2, with EC50 values ranging from 0.002 to 0.005 μM in different cell lines. Derivative 3 also exhibited significant antiviral activity against DENV-2. The study found that these compounds are effective at inhibiting DENV-2 at both the entry stage (including virus attachment) and post-entry stages of the viral life cycle. The study also investigated the inhibition of the DENV-2 NS2B-NS3 protease activity by these compounds. Derivative 6 demonstrated notably stronger inhibition compared to mCy thio 3, revealing its dual antiviral action at both the entry and post-entry stages. Molecular docking simulations indicated that mCy thio derivatives 3 and 6 bind to the domain I and III of the DENV E protein, as well as the active of NS2B-NS3 protease, suggesting their molecular interactions with the virus. The study demonstrates the antiviral efficacy of N-methylcytisine thio derivatives against DENV. It provides valuable insights into the potential interactions between these compounds and viral target proteins, which could be useful in the development of antiviral drugs for DENV.

Selective inhibition of hepatitis B virus internalization by oxysterol derivatives

Given that the current approved anti-hepatitis B virus (HBV) drugs suppress virus replication and improve hepatitis but cannot eliminate HBV from infected patients, new anti-HBV agents with different mode of action are urgently needed. In this study, we identified a semi-synthetic oxysterol, Oxy185, that can prevent HBV infection in a HepG2-based cell line and primary human hepatocytes. Mechanistically, Oxy185 inhibited the internalization of HBV into cells without affecting virus attachment or replication. We also found that Oxy185 interacted with an HBV entry receptor, sodium taurocholate cotransporting polypeptide (NTCP), and inhibited the oligomerization of NTCP to reduce the efficiency of HBV internalization. Consistent with this mechanism, Oxy185 also inhibited the hepatitis D virus infection, which relies on NTCP-dependent internalization, but not hepatitis A virus infection, and displayed pan-genotypic anti-HBV activity. Following oral administration in mice, Oxy185 showed sustained accumulation in the livers of the mice, along with a favorable liver-to-plasma ratio. Thus, Oxy185 is expected to serve as a useful tool compound in proof-of-principle studies for HBV entry inhibitors with this novel mode of action.

ORFV entry into host cells via clathrin-mediated endocytosis and macropinocytosis

Orf virus (ORFV), also known as infectious pustular virus, leads to an acute contagious zoonotic infectious disease. ORFV can directly contact and infect epithelial cells of skin and mucosa, causing damage to tissue cells. So far, the pathway of ORFV entry into cells is unclear. Therefore, finding the internalization pathway of ORFV will help to elucidate the cellular and molecular mechanisms of ORFV infection and invasion, which in turn will provide a certain reference for the prevention and treatment of ORFV. In the present study, chemical inhibitors were used to analyze the mechanism of ORFV entry into target cells. The results showed that the inhibitor of clathrin-mediated endocytosis could inhibit ORFV entry into cells. However, the inhibitor of caveolae-mediated endocytosis cannot inhibit ORFV entry into cells. In addition, inhibition of macropinocytosis pathway also significantly reduced ORFV internalization. Furthermore, the inhibitors of acidification and dynamin also prevented ORFV entry. However, results demonstrated that inhibitors inhibited ORFV entry but did not inhibit ORFV binding. Notably, extracellular trypsin promoted ORFV entry into cells directly, even when the endocytic pathway was inhibited. In conclusion, ORFV enters into its target cells by clathrin-mediated endocytosis and macropinocytosis, while caveolae-dependent endocytosis has little effects on this process. In addition, the entry into target cells by ORFV required an acid environment and the effect of dynamin. Meanwhile, we emphasize that broad-spectrum antiviral inhibitors and extracellular enzyme inhibitors are likely to be effective strategies for the prevention and treatment of ORFV infection.

Identification of alpha-linolenic acid as a broad-spectrum antiviral against zika, dengue, herpes simplex, influenza virus and SARS-CoV-2 infection

Zika virus (ZIKV) has garnered global attention due to its association with severe congenital defects including microcephaly. However, there are no licensed vaccines or drugs against ZIKV infection. Pregnant women have the greatest need for treatment, making drug safety crucial. Alpha-linolenic acid (ALA), a polyunsaturated ω-3 fatty acid, has been used as a health-care product and dietary supplement due to its potential medicinal properties. Here, we demonstrated that ALA inhibits ZIKV infection in cells without loss of cell viability. Time-of-addition assay revealed that ALA interrupts the binding, adsorption, and entry stages of ZIKV replication cycle. The mechanism is probably that ALA disrupts the membrane integrity of the virions to release ZIKV RNA, inhibiting viral infectivity. Further examination revealed that ALA inhibits DENV-2, HSV-1, influenza virus and SARS-CoV-2 infection dose-dependently. ALA is a promising broad-spectrum antiviral agent.

Business dynamism, sectoral reallocation and productivity in a pandemic

Asymmetric effects across sectors are the distinctive features of the Covid-19 shock. An Epidemiological-Industry Dynamic model with heterogeneous firms and endogenous firms dynamics mimics the deep recession suffered by sectors characterized by high exposure, the reallocation of entry and exit opportunities across sectors, and the dynamics of aggregate productivity during the first wave of the pandemic. The cleansing effect induced by the Covid-19 crisis is sector-specific. Monetary policy and sticky wages are central ingredients to capture reallocation effects. Social distancing, by smoothing out cleansing in the social sector, slows down the reallocation process and prolongs the recession, but saves lives.

Intensified pulmonary tuberculosis case finding among HIV-infected new entrants of a prison in Malaysia: implications for a holistic approach to control tuberculosis in prisons

PURPOSE

This intensified case finding study aimed to evaluate the prevalence of tuberculosis (TB) disease among people with HIV entering the largest prison in Malaysia.

DESIGN/METHODOLOGY/APPROACH

The study was conducted in Kajang prison, starting in July 2013 in the men's prison and June 2015 in the women's prison. Individuals tested positive for HIV infection, during the mandatory HIV testing at the prison entry, were consecutively recruited over five months at each prison. Consented participants were interviewed using a structured questionnaire and asked to submit two sputum samples that were assessed using GeneXpert MTB/RIF (Xpert) and culture, irrespective of clinical presentation. Factors associated with active TB (defined as a positive result on either Xpert or culture) were assessed using regression analyses.

FINDINGS

Overall, 214 incarcerated people with HIV were recruited. Most were men (84.6%), Malaysians (84.1%) and people who inject drugs (67.8%). The mean age was 37.5 (SD 8.2) years, and median CD4 lymphocyte count was 376 cells/mL (IQR 232-526). Overall, 27 (12.6%) TB cases were identified, which was independently associated with scores of five or more on the World Health Organization clinical scoring system for prisons (ARR 2.90 [95% CI 1.48-5.68]).

ORIGINALITY/VALUE

Limited data exists about the prevalence of TB disease at prison entry, globally and none from Malaysia. The reported high prevalence of TB disease in the study adds an important and highly needed information to design comprehensive TB control programmes in prisons.

Longitudinal morphological changes of the aorta and the endograft position before and after distal stent graft-induced new entry in aortic dissections

OBJECTIVES

The aim of this study was to assess the endograft position and aortic geometry changes after thoracic endovascular aortic repair (TEVAR) and frozen elephant trunk (FET) in distal stent-induced new entry (dSINE) patients.

METHODS

In this retrospective cohort study, the baseline demographic and the follow-up data were extracted from the hospital records, and computed tomography scans of dSINE patients after TEVAR or FET between 2011 and 2021 were analysed regarding endograft oversizing, length and migration, taper ratio, aortic diameter at the endograft end, aortic elongation (thoracic inner and outer curvature), wedge apposition angle and tortuosity angle in the distal landing zone.

RESULTS

dSINE was found in 22/213 (10%) of TEVAR and 10/31 (32%) of FET patients. The total follow-up time was 45 (27; 59) months. TEVAR was mainly performed with Relay NBS endograft (77%) and FET with Evita open prosthesis (80%). Paraplegia and stroke rates were 3%. dSINE occurred 17 (7; 35) months post-TEVAR and was instantly treated in 18 patients (56%) or followed up for 21 (11; 34) months (n = 14). Migration [+5 mm (1; 11; P < 0.001)], birdbeak angle [+9° (0; 27; P = 0.039)] and aortic diameter +5 mm (1; 11; P < 0.001) increased after dSINE, whereas aortic elongation increased already before [+12 mm (0; 27; P = 0.015)] and peaked after dSINE [+30 mm (9; 38; P < 0.001)]. The aortic elongation was more pronounced in the outer aortic curvature before and after dSINE (before: P = 0.039, after: P = 0.024). Postoperative wedge apposition [17° (12; 20)] increased before dSINE [21° (16; 35; P < 0.001)] and peaked thereafter [31° (21; 40; P < 0.001)].

CONCLUSIONS

Aortic elongation may influence the endograft position and provoke TEVAR failure in the distal and proximal landing zones.

Antiviral role of IFITM3 in prototype foamy virus infection

BACKGROUND

Foamy viruses (FVs) are retroviruses with unique replication strategies that cause lifelong latent infections in their hosts. FVs can also produce foam-like cytopathic effects in vitro. However, the effect of host cytokines on FV replication requires further investigation. Although interferon induced transmembrane (IFITMs) proteins have become the focus of antiviral immune response research due to their broad-spectrum antiviral ability, it remains unclear whether IFITMs can affect FV replication.

METHOD

In this study, the PFV virus titer was characterized by measuring luciferase activity after co-incubation of PFVL cell lines with the cell culture supernatants (cell-free PFV) or the cells transfected with pcPFV plasmid/infected with PFV (cell-associated PFV). The foam-like cytopathic effects of PFV infected cells was observed to reflect the virus replication. The total RNA of PFV infected cells was extracted, and the viral genome was quantified by Quantitative reverse transcription PCR to detect the PFV entry into target cells.

RESULTS

In the present study, we demonstrated that IFITM1-3 overexpression inhibited prototype foamy virus (PFV) replication. In addition, an IFITM3 knockdown by small interfering RNA increased PFV replication. We further demonstrated that IFITM3 inhibited PFV entry into host cells. Moreover, IFITM3 also reduced the number of PFV envelope proteins, which was related to IFITM3 promoted envelope degradation through the lysosomal pathway.

CONCLUSIONS

Taken together, these results demonstrate that IFITM3 inhibits PFV replication by inhibiting PFV entry into target cells and reducing the number of PFV envelope.

Novel Naturally Occurring Dipeptides and Single-Stranded Oligonucleotide Act as Entry Inhibitors and Exhibit a Strong Synergistic Anti-HIV-1 Profile

Introduction

The availability of new classes of antiretroviral drugs is critical for treatment-experienced patients due to drug resistance to and unwanted side effects from current drugs. Our aim was therefore to evaluate the anti-HIV-1 activity of a new set of antivirals, dipeptides (WG-am or VQ-am) combined with a single-stranded oligonucleotide (ssON). The dipeptides were identified as naturally occurring and enriched in feces and systemic circulation in HIV-1-infected elite controllers and were proposed to act as entry inhibitors by binding to HIV-1 gp120. The ssON is DNA 35-mer, stabilized by phosphorothioate modifications, which acts on the endocytic step by binding to cell host receptors and inhibiting viruses through interference with binding to nucleolin.

Methods

Chou–Talalay’s Combination Index method for quantifying synergism was used to evaluate the drug combinations. Patient-derived chimeric viruses encoding the gp120 (env region) were produced by transient transfection and used to evaluate the antiviral profile of the combinations by drug susceptibility assays.

Results

We found that the combination WG-am:ssON or VQ-am:ssON had low combination index values, suggesting strong antiviral synergism. Of the two combinations, WG-am:ssON (1 mM:1 μM) had high efficacy against all prototype or patient-derived HIV-1 isolates tested, independent of subtype including the HIV-1-A6 sub-subtype. In addition, the antiviral effect was independent of co-receptor usage in patient-derived strains.

Conclusion

WG-am and ssON alone significantly inhibited HIV-1 replication regardless of viral subtype and co-receptor usage, and the combination WG-am:ssON (1 mM:1 μM) was even more effective due to synergism.

Synergistic in-vitro antiviral effects of combination treatment using anidulafungin and T-1105 against Zika virus infection

Zika virus (ZIKV) has been the cause of some epidemics since 2007. The correlations of microcephaly and Guillain-Barré syndrome with ZIKV have been noticed. Unfortunately, researchers have yet to develop an effective vaccine or drug approved for ZIKV infection. Anidulafungin is a member of echinocandins that is used to treat candida infections. This study assessed the antiviral capability of anidulafungin against ZIKV. Anidulafungin was shown to significantly decrease viral RNA levels, protein expression levels, viral yields, and the rate of infection. In time of addition assays, anidulafungin exhibited inhibitory activities in the early stages of ZIKV infection. In binding and entry assays, administering anidulafungin did not lead to a corresponding decrease in quantity of viral RNA, but a significant decrease in ZIKV infectivity was observed in virucidal assays. This indicated that anidulafungin interferes directly with virions. T-1105 is a viral polymerase inhibitor, which functions in the late stage of ZIKV infection. When anidulafungin was administered in combination with T-1105, an obvious synergistic effect was observed, resulting in a combination index (CI) value of 0.85 ± 0.13. Finally, we evaluated the effects of echinocandins in terms of half-maximal inhibitory concentration (IC₅₀), calculation of cytotoxicity concentration 50% (CC₅₀), selectivity index (SI), and Patchdock score. Among the tests, anidulafungin bears the lowest IC₅₀ and highest Patchdock score. Although anidulafungin is classified as a pregnancy category C agent; however, combination therapy of anidulafungin with a viral RNA replication inhibitor could expand treatment options for ZIKV infection.

Differentiated Entry or "Me-Too" Entry in Bertrand and Cournot Oligopoly

When would an oligopolistic entrant imitate an incumbent's product ("me-too" entry), rather than horizontally differentiate? We allow an entrant's product choice to vary endogenously with the cost of product differentiation. Such endogenity of product differentiation significantly affects the comparison of Bertrand and Cournot duopoly. We find that if Bertrand entry occurs, products are differentiated, whereas there is a substantial region in which Cournot entry involves a homogenous product. Bertrand prices may be higher than Cournot prices; and, if product differentiation costs are low enough to induce Cournot differentiated entry, then Bertrand industry profit equals or exceeds Cournot industry profit.

Elevated NTCP expression by an iPSC-derived human hepatocyte maintenance medium enhances HBV infection in NTCP-reconstituted HepG2 cells

BACKGROUND

The sodium taurocholate cotransporting polypeptide (NTCP) is a functional receptor for hepatitis B virus (HBV). NTCP-reconstituted human hepatoma cells support HBV infection, but the infection is suboptimal and no apparent HBV spread has been observed in this system.

RESULTS

We found that NTCP-reconstituted HepG2 cells were highly susceptible to HBV infection after cells were cultured in a commercial human inducible pluripotent stem cell (iPSC)-derived hepatocyte maintenance medium (HMM). The enhanced HBV infection coincided with increased NTCP expression, and was observed in six different clones of HepG2-NTCP cells. Promoter assays indicated that HMM activated the cytomegalovirus immediate-early (IE) promoter that drives the NTCP expression in the HepG2-NTCP cells. RNA-Seq analysis revealed that HMM upregulated multiple metabolic pathways. Despite highly upregulated NTCP expression by HMM, no obvious HBV spread was observed even in the presence of PEG 8000.

CONCLUSIONS

Our data suggest that this particular medium could be used to enhance HBV infection in NTCP-reconstituted hepatocytes in vitro.

Translocation of the nonlabeled antimicrobial peptide PGLa across lipid bilayers and its entry into vesicle lumens without pore formation

Fluorescent-probe-labeled peptides are used to study the interactions of peptides with cells and lipid vesicles but labeling peptides with fluorescent probes can significantly change these interactions. We recently developed a new method to detect the entry of nonlabeled peptides into the lumen of single giant unilamellar vesicles (GUVs). Here we applied this method to examine the interaction of the antimicrobial peptide PGLa with single GUVs to elucidate whether PGLa can enter the GUV lumen without pore formation. First, we examined the interaction of nonlabeled PGLa with single GUVs comprising dioleoylphosphatidylglycerol (DOPG) and dioleoylphosphatidylcholine (DOPC) (4/6) whose lumens contain the fluorescent probe AF647 and DOPG/DOPC (8/2)-large unilamellar vesicles encapsulating a high concentration of calcein. After a large lag period from starting the interaction with PGLa, the fluorescence intensity of the GUV lumen due to calcein (I_calcein) increased gradually without leakage of AF647, indicating that PGLa enters the GUV lumen without pore formation in the GUV membrane. The fraction of entry of PGLa increased with increasing PGLa concentration. Simultaneous measurement of the fractional area change of the GUV membrane (δ) and PGLa-induced increase in I_calcein showed that the entry of PGLa occurs only during the second increase in δ, indicating that PGLa enters the lumen during its translocation from the outer leaflet to the inner leaflet. The fraction of entry of PGLa without pore formation increased with increasing membrane tension. Based on these results, we discuss the elementary processes and the mechanism of the entry of PGLa into the GUV lumen.

Expression of the human or porcine C-type lectins DC-SIGN/L-SIGN confers susceptibility to porcine epidemic diarrhea virus entry and infection in otherwise refractory cell lines

Porcine epidemic diarrhea virus (PEDV) is an alphacoronavirus that causes great economic losses in the porcine industry. Although the functional receptor for the virus has not been identified, multiple isolates are able to infect different cell lines. Recently, it has been shown that the human C-type lectin DC-SIGN/L-SIGN (hDC-SIGN/L-SIGN) can promote entry of several coronaviruses. Here we examined whether hDC-SIGN/L-SIGN and its porcine homolog (pDC-SIGN) are entry determinants for PEDV. Expression of hDC-SIGN/L-SIGN or pDC-SIGN in refractory cells dramatically increased infection by a recombinant PEDV expressing green fluorescent protein. In both cases, lectin-mediated infection was inhibited by mannan or anti-hDC-SIGN/L-SIGN or pDC-SIGN antibodies; however, d-galactose had no effect on the virus-infected cells. Our results demonstrate that hDC-SIGN/L-SIGN or pDC-SIGN can mediate the cellular entry and propagation of PEDV, which provides a new theoretical basis for further understanding the infection mechanism of PEDV, and will be helpful for the development of novel therapeutic agents.

A new high-content screening assay of the entire hepatitis B virus life cycle identifies novel antivirals

Background & Aims

Chronic hepatitis B is an incurable disease. Addressing the unmet medical need for therapies has been hampered by a lack of suitable cell culture models to investigate the HBV life cycle in a single experimental setup. We sought to develop a platform suitable to investigate all aspects of the entire HBV life cycle.

Methods

HepG2-NTCPsec+ cells were inoculated with HBV. Supernatants of infected cells were transferred to naïve cells. Inhibition of infection was determined in primary and secondary infected cells by high-content imaging of viral and cellular factors. Novel antivirals were triaged in cells infected with cell culture- or patient-derived HBV and in stably virus replicating cells. HBV internalisation and target-based receptor binding assays were conducted.

Results

We developed an HBV platform, screened 2,102 drugs and bioactives, and identified 3 early and 38 late novel HBV life cycle inhibitors using infectious HBV genotype D. Two early inhibitors, pranlukast (EC₅₀ 4.3 μM; 50% cytotoxic concentration [CC₅₀] >50 μM) and cytochalasin D (EC₅₀ 0.07 μM; CC₅₀ >50 μM), and 2 late inhibitors, fludarabine (EC₅₀ 0.1 μM; CC₅₀ 13.4 μM) and dexmedetomidine (EC₅₀ 6.2 μM; CC₅₀ >50 μM), were further investigated. Pranlukast inhibited HBV preS1 binding, whereas cytochalasin D prevented the internalisation of HBV. Fludarabine inhibited the secretion of HBV progeny DNA, whereas dexmedetomidine interfered with the infectivity of HBV progeny. Patient-derived HBV genotype C was efficiently inhibited by fludarabine (EC₅₀ 0.08 μM) and dexmedetomidine (EC₅₀ 8.7 μM).

Conclusions

The newly developed high-content assay is suitable to screen large-scale drug libraries, enables monitoring of the entire HBV life cycle, and discriminates between inhibition of early and late viral life cycle events.

Lay summary

HBV infection is an incurable, chronic disease with few available treatments. Addressing this unmet medical need has been hampered by a lack of suitable cell culture models to study the entire viral life cycle in a single experimental setup. We developed an image-based approach suitable to screen large numbers of drugs, using a cell line that can be infected by HBV and produces large amounts of virus particles. By transferring viral supernatants from these infected cells to uninfected target cells, we could monitor the entire viral life cycle. We used this system to screen drug libraries and identified novel anti-HBV inhibitors that potently inhibit HBV in various phases of its life cycle. This assay will be an important new tool to study the HBV life cycle and accelerate the development of novel therapeutic strategies.

•

We developed a high-content screening assay suitable to monitor the entire HBV life cycle and eligible to discriminate between early and late viral life cycle inhibition.

•

We screened FDA-approved drugs and bioactives.

•

We confirmed antiviral activity in primary and secondary assays, using stably virus replicating cells and cell culture- and patient-derived HBV.

•

Novel HBV inhibitors prevent receptor binding, virus internalisation, replication, or egress of viral progeny.

Variations in Env at amino acids 328 and 330 affect HIV-1 replicative fitness and entry inhibitor sensitivity

While the variations in the HIV-1 Env V3 loop have been the focus of much research to explore its functional effect, how specific mutations of certain amino acids in the V3 loop affect viral fitness remains unclear. In this study, we evaluated a series of natural polymorphisms at positions 328 and 330 with different combinations of adjacent glycosylation sites in the HIV-1 subtype B backbone to address their role in replicative fitness and sensitivity to entry inhibitors based on analysis of env sequence frequency at the population level. Pairwise growth competition experiment showed that wild-type virus with major consensus amino acids obviously had higher replicative fitness (P < 0.001). A change at position 328 to a less frequently occurring amino acid, K, together with a mutated N332 glycosylation site harbored lower fitness and became more sensitive to coreceptor antagonists (AMD3100), fusion inhibitors (T20) and sCD4. A change at position 330 to a less frequently occurring amino acid, Y, together with a mutated N332 glycosylation site resulted in higher fitness and less sensitivity to entry inhibitors (T20, AMD3100, and sCD4), and viruses containing both changes showed intermediate activity. It seems that the H330Y mutation compensated for the reduced replicative capacity caused by the Q328 K mutation. Moreover, viruses that showed lower replicative fitness also exhibited slower entry kinetics, lower levels of replication intermediates and protein packaging, and a lower ability to replicate in primary peripheral blood mononuclear cells (PBMCs). The findings highlight the functional effect of variations at 328 and 330 in the V3 loop on replicative fitness and may benefit HIV-1 treatment by helping predict the sensitivity to entry inhibitors.

Chimeric Zika viruses containing structural protein genes of insect-specific flaviviruses cannot replicate in vertebrate cells due to entry and post-translational restrictions

Long Pine Key virus (LPKV) and Lammi virus are insect-specific flaviviruses that phylogenetically affiliate with dual-host flaviviruses. The goal of this study was to provide insight into the genetic determinants that condition this host range restriction. Chimeras were initially created by replacing select regions of the Zika virus genome, including the premembrane and envelope protein (prM-E) genes, with the corresponding regions of the LPKV genome. Of the four chimeras produced, one (the prM-E swap) yielded virus that replicated in mosquito cells. Another chimeric virus with a mosquito replication-competent phenotype was created by inserting the prM-E genes of Lammi virus into a Zika virus genetic background. Vertebrate cells did not support the replication of either chimeric virus although trace to modest amounts of viral antigen were produced, consistent with suboptimal viral entry. These data suggest that dual-host affiliated insect-specific flaviviruses cannot replicate in vertebrate cells due to entry and post-translational restrictions.

Randomized control trial on effectiveness and safety of direct trocar versus Veress needle entry techniques in obese women during diagnostic laparoscopy

PURPOSE

To determine the benefits and safety of direct trocar insertion versus Veress needle technique in obese women undertaking diagnostic laparoscopy procedures.

METHODS

Randomized-controlled trial on 135 obese women undergoing diagnostic laparoscopy and dye test for infertility was conducted. Women were randomly assigned to either direct trocar access (n = 68) or Veress needle access (n = 67) before achieving pneumoperitoneum. The same surgeon executed the laparoscopic techniques with a single-puncture technique. The primary outcome measures included total length of the procedure and incidence of any complications, while the mean laparoscopic entry time, volume of CO₂ required, and total of tries needed to attain successful entry were secondary outcomes. Intention-to-treat principle was applied to analysis.

RESULTS

Women in both groups had similar socio-demographic and clinical characteristics and none were lost to follow-up. The overall length of the procedure was significantly lesser in the direct trocar group compared to the Veress needle group (9.9 ± 6.0 vs 16.7 ± 4.7 min; p < 0.001). No significant differences occurred in other outcomes including mean entry time, volume of CO₂ used, number of attempts for successful entry, and major/minor complications (p > 0.05).

CONCLUSIONS

Direct trocar technique may be an effective alternative to Veress needle for pneumoperitoneum in obese women for diagnostic laparoscopy. It has a comparable rapid laparoscopic entry time but a significantly lower duration of the procedure and shorter exposure to anesthesia. Both methods are equally effective as there was no significant difference in the complications recorded. A greater sample trial may be essential for more corroborative substantiation.

CLINICAL TRIAL REGISTRATION

PACTR201510000999192.

Anti-Influenza Drug Discovery and Development: Targeting the Virus and Its Host by All Possible Means

Infections by influenza virus constitute a major and recurrent threat for human health. Together with vaccines, antiviral drugs play a key role in the prevention and treatment of influenza virus infection and disease. Today, the number of antiviral molecules approved for the treatment of influenza is relatively limited, and their use is threatened by the emergence of viral strains with resistance mutations. There is therefore a real need to expand the prophylactic and therapeutic arsenal. This chapter summarizes the state of the art in drug discovery and development for the treatment of influenza virus infections, with a focus on both virus-targeting and host cell-targeting strategies. Novel antiviral strategies targeting other viral proteins or targeting the host cell, some of which are based on drug repurposing, may be used in combination to strengthen our therapeutic arsenal against this major pathogen.

Understanding Severe Acute Respiratory Syndrome Coronavirus 2 Replication to Design Efficient Drug Combination Therapies

BACKGROUND

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its disease CO-VID-19 has strongly encouraged the search for antiviral compounds. Most of the evaluated drugs against SARS-CoV-2 derive from drug repurposing of Food and Drug Administration-approved molecules. These drugs have as target three major processes: (1) early stages of virus-cell interaction, (2) viral proteases, and (3) the viral RNA-dependent RNA polymerase.

SUMMARY

This review focused on the basic principles of virology and pharmacology to understand the importance of early stages of virus-cell interaction as therapeutic targets and other main processes vital for SARS-CoV-2 replication. Furthermore, we focused on describing the main targets associated with SARS-CoV-2 antiviral therapy and the rationale of drug combinations for efficiently suppressing viral replication. Key Messages: We hypothesized that blocking of both entry mechanisms could allow a more effective antiviral effect compared to the partial results obtained with chloroquine or its derivatives alone. This approach, already used to achieve an antiviral effect higher than that offered by every single drug administered separately, has been successfully applied in several viral infections such as HIV and HCV. This review will contribute to expanding the perception of the possible therapeutic targets in SARS-CoV-2 infection and highlight the benefits of using combination therapies.

Involvement of the nervous system in COVID-19: The bell should toll in the brain

The world is fuming at SARS-CoV-2 for being the culprit for causing the devastating COVID-19, claiming millions of lives across the globe in the form of respiratory disorders. But lesser known are its effects on the CNS that are slowly surfacing in the worldwide population. Our review illustrates findings that claim SARS-CoV-2's arrival onto the ACE2 receptors of neuronal and glial cells mainly via CSF, olfactory nerve, trigeminal nerve, neuronal dissemination, and hematogenous pathways. The role of SARS-CoV-2 structural proteins in its smooth viral infectivity of the host cannot be ignored, especially the spike proteins that mediate spike attachment and host membrane fusion. Worth mentioning the nucleocapsid, envelope, and membrane proteins make the proliferation of SARS-CoV-2 much simpler than expected in spreading infection. This has led to catastrophic conditions like seizures, Guillain-Barré syndrome, viral encephalitis, meningoencephalitis, acute cerebrovascular disease, and respiratory failures. Placing a magnifying lens on the lesser-explored CNS consequences of COVID-19, we attempt to shift the focus of our readers onto the new supporting threats to which further studies are needed.

Aortic dissection reconsidered: type, entry site, malperfusion classification adding clarity and enabling outcome prediction

OBJECTIVES

Aortic dissection is complex. Imaging and treatment modalities are evolving, demanding a more differentiated but pragmatic dissection classification. Our goal was to provide a new practical classification system including Type of dissection, location of the tear of the primary Entry and Malperfusion (TEM).

METHODS

We extended the Stanford dissection classification (A and B) by adding non-A non-B aortic dissection, the location of the primary entry tear (E) and malperfusion (M). A 0 was added if the primary entry tear was not visible; 1, if it was in the ascending aorta; 2, if it was in the arch; and 3, if it was in the descending aorta (E0, E1, E2, E3). We added 0 if malperfusion was absent; 1, if coronary arteries; 2, if supra-aortic vessels; and 3, if visceral/renal and/or a lower extremity was affected (M0, M1, M2, M3). Plus (+) was added if malperfusion was clinically present and minus (-) if it was a radiological finding.

RESULTS

The new classification system was analysed in 357 patients retrospectively; distribution was 59%, 31% and 10% for A, B and non-A non-B dissections. The in-hospital mortality rate was 16%, 5% and 8% (P = 0.01). Postoperative stroke occurred in 14%, 1% and 3% (P < 0.001). The in-hospital mortality rate was 22%, 14%, 40% and 0% in A E0, E1, E2 and E3 (P = 0.023), respectively. Two years after the onset of dissection, the lowest survival rate was observed in A, followed by non-A non-B and B (83 ± 3% vs 88 ± 6% vs 93 ± 3%; P = 0.019).

CONCLUSIONS

The new practical TEM aortic dissection classification system adds clarity regarding the extent of the disease process, enhances awareness of the disease mechanism, aids in decision-making regarding the extent of repair and helps in anticipating outcome.

Hepatitis B virus biology and life cycle

Hepatitis B virus (HBV) specifically infects hepatocytes and causes severe liver diseases. The HBV life cycle is unique in that the genomic DNA (relaxed-circular partially double-stranded DNA: rcDNA) is converted to a molecular template DNA (covalently closed circular DNA: cccDNA) to amplify a viral RNA intermediate, which is then reverse-transcribed back to viral DNA. The highly stable characteristics of cccDNA result in chronic infection and a poor rate of cure. This complex life cycle of HBV offers a variety of targets to develop antiviral agents. We provide here an update on the current knowledge of HBV biology and its life cycle, which may help to identify new antiviral targets.

Tetraspanin CD9 affects HPV16 infection by modulating ADAM17 activity and the ERK signalling pathway

Human papillomaviruses (HPV) are causative agents of various tumours such as cervical cancer. HPV binding to the cell surface of keratinocytes leads to virus endocytosis at tetraspanin enriched microdomains. Complex interactions of the capsid proteins with host proteins as well as ADAM17-dependent ERK1/2 signal transduction enable the entry platform assembly of the oncogenic HPV type 16. Here, we studied the importance of tetraspanin CD9, also known as TSPAN29, in HPV16 infection of different epithelial cells. We found that both overexpression and loss of the tetraspanin decreased infection rates in cells with low endogenous CD9 levels, while reduction of CD9 expression in keratinocytes that exhibit high-CD9 protein amounts, led to an increase of infection. Therefore, we concluded that low-CD9 supports infection. Moreover, we found that changes in CD9 amounts affect the shedding of the ADAM17 substrate transforming growth factor alpha (TGFα) and the downstream phosphorylation of ERK. These effects correlate with those on infection rates suggesting that a specific CD9 optimum promotes ADAM17 activity, ERK signalling and virus infection. Together, our findings implicate that CD9 regulates HPV16 infection through the modulation of ADAM17 sheddase activity.

Single-nucleotide variants in human CD81 influence hepatitis C virus infection of hepatoma cells

An estimated number of 71 million people are living with chronic hepatitis C virus (HCV) infection worldwide and 400,000 annual deaths are related to the infection. HCV entry into the hepatocytes is complex and involves several host factors. The tetraspanin human CD81 (hCD81) is one of the four essential entry factors and is composed of one large extracellular loop, one small extracellular loop, four transmembrane domains, one intracellular loop and two intracellular tails. The large extracellular loop interacts with the E2 glycoprotein of HCV. Regions outside the large extracellular loop (backbone) of hCD81 have a critical role in post-binding entry steps and determine susceptibility of hepatocytes to HCV. Here, we investigated the effect of five non-synonymous single-nucleotide variants in the backbone of hCD81 on HCV susceptibility. We generated cell lines that stably express the hCD81 variants and infected the cells using HCV pseudoparticles and cell culture-derived HCV. Our results show that all the tested hCD81 variants support HCV pseudoparticle entry with similar efficiency as wild-type hCD81. In contrast, variants A54V, V211M and M220I are less supportive to cell culture-derived HCV infection. This altered susceptibility is HCV genotype dependent and specifically affected the cell entry step. Our findings identify three hCD81 genetic variants that are impaired in their function as HCV host factors for specific viral genotypes. This study provides additional evidence that genetic host variation contributes to inter-individual differences in HCV infection and outcome.

Cholesterol-rich lipid rafts both in cellular and viral membrane are critical for caprine parainfluenza virus type3 entry and infection in host cells

Cholesterol-rich lipid rafts have been shown to play important roles in the life cycle of various non-enveloped and enveloped viruses. Deletion of cholesterol from lipid rafts could influence different steps of viral replication cycle including entry, infection, assembly and release. Caprine parainfluenza virus type3 (CPIV3) is a newly identified member of Paramyxoviridae family. CPIV3 is highly prevalence and threatened the goat industry in China. The infection mechanism of CPIV3 is under exploring and still not fully understood, the roles of cholesterol and lipid rafts for CPIV3 infection remains unclear. In this study, we investigated the association of cholesterol and lipid rafts with CPIV3 during the different viral replication stages (binding, entry and infection) in two cells [MDBK and goat bronchial epithelial (GBE) cells]. Methyl-β- cyclodextrin (MβCD) was used to deplete cholesterol from cell and viral membranes. The results showed that MβCD treatment significantly inhibited CPIV3 entry and infection in these two cells with a dose-dependent manner, but didn't impair the binding of CPIV3. Addition of exogenous cholesterol to the cells after MβCD treatment restored the viral infection. In addition, treatment of MβCD only before virus-entry showed inhibitory effect in MDBK cells. Depletion of cholesterol from virion envelop also decreased the entry and infection of CPIV3 in the two cells. Furthermore, lipid rafts isolation test indicated that viral proteins (HN and N) co-localized with lipid rafts during infection in MDBK and GBE cells. Viral N protein co-localized with caveolin-1 (the marker of lipid rafts) in these two cells both at the entry and infection steps, as detected by con-focal laser scanning microscopy test. In conclusion, the results presented here demonstrated that cholesterol rich lipid rafts play an important role in CPIV3 life cycle. The findings give new insights on understanding of the mechanism of CPIV3 infection and provide a new anti-CPIV3 strategy.

SARS-CoV-2 entry in host cells-multiple targets for treatment and prevention

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new viral disease that has gained global attention owing to its ability to provoke community and health-care-associated outbreaks of severe infections in human populations. The virus poses serious challenges to clinical management because there are still no approved anti- SARS-CoV-2 drugs available. In this mini-review, we summarize the much updated published reports that demonstrate the mechanism of SARS-CoV-2 entry into host cells, and discuss the availability and development of attractive host-based therapeutic options for SARS-CoV-2 infections.

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Interplay between virus spike protein, ACE2 and host proteases in mediating entry of SARS-CoV-2 in host cells.

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Association between ACE2 expression, comorbidities and severity of SARS-CoV-2 infection.

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Inhibitors of endosomal acidification, TMPRSS and cathepsin proteases are candidate therapeutics of SARS-CoV-2.

Heparin sulfate is the attachment factor of duck Tembus virus on both BHK21 and DEF cells

BACKGROUND

Duck tembusu virus (DTMUV, genus Flaviviruses, family Flaviviridae) is an emerging flavivirus that can infect a wide range of cells and cell lines in vitro, though the initial step of virus invasion remains obscure.

METHODS

In this study, drug treatments that including heparin, chondroitin sulfate, heparinase I, chondroitinase ABC and trypsin were applied to detect the influence of DTMUV absorption, subsequently, the copy number of viral genome RNA was analyzed by quantitative real-time PCR. The inhibition process of viral absorption or entry by heparin was determined by western blotting, and the cytotoxicity of drug treated cells was detected by cell counting kit-8.

RESULTS

We found that the desulfation of glycosaminoglycans (GAGs) with sodium chlorate had a significant effect on the adsorption of DTMUV in both BHK21 and DEF cells. Based on this result, we incubated cells with a mixture of DTMUV and GAGs competition inhibitors or pre-treated cells with inhibitors, after incubation with the virus, the NS5 expression of DTMUV and viral titers were detected. The data suggested that heparin can significantly inhibit the absorption of DTMUV in a dose dependent manner but not at the step of viral entry in BHK21 and DEF cells. Meanwhile, heparinase I can significantly inhibit DTMUV attachment step.

CONCLUSIONS

Our results clearly proved that heparin sulfate plays an important role in the first step of DTMUV entry, viral attachment, in both BHK21 and DEF cells, which sheds light on the entry mechanism of DTMUV.

The HIV-1 Capsid: More than Just a Delivery Package

Productive HIV infection requires integration of viral genes into the host genome. But how viral DNA gets to the nucleus in the first place remains one of the most controversial yet deceptively simple questions in HIV post-entry biology. This is illustrated in cartoons of viral entry, which often depict the entry process as an 'explosion' of the HIV capsid in the cytosol and independent movement of viral DNA through nuclear pores and into the nucleus. HIV enters the cell cytosol with two encapsidated RNA strands and must undergo reverse transcription (RT) to synthesise DNA. Even here there is no consensus for where, when or how RT happens. HIV must get into the nucleus, which in a non-dividing cell requires transport through the nuclear pore. Finally, the virus must 'uncoat': shed its protein capsid to allow its DNA to be spliced with that of the host. Where the virus uncoats and whether this is a single or multi-step process are similarly hotly debated. Understanding these processes is further complicated by three broad factors. First, that there are inter-relationships between these processes that may ensure HIV undergoes the right step at the right place at the right time. Second, the host has cofactors which the virus is dependent upon and must recruit but also immune factors that can sense and inhibit virus and so must be avoided. Third, HIV post-entry biology is cell-type dependent-meaning that factors which are essential in one cell type can be redundant in another.

Palmatine inhibits Zika virus infection by disrupting virus binding, entry, and stability

Zika virus (ZIKV) is an emerging vector-borne virus that is associated with severe congenital cerebral anomalies in fetuses and paralytic Guillain-Barré syndrome in adults. In the current global health crisis, there are no vaccines or therapeutics available for the treatment of ZIKV infection. In the present study, we evaluated the efficacy of the protoberberine alkaloid, palmatine, in inhibiting ZIKV and Japanese encephalitis virus (JEV). Palmatine was shown to bind to restricted viruses, inhibit ZIKV infection, and resist ZIKV-induced cytopathic effects. Palmatine was also shown to inhibit JEV infection in multiple cell lines. Overall, the effects of palmatine in disrupting ZIKV binding, entry, and stability indicate that this small molecule would be a good starting point for the development of treatments aimed at inhibiting ZIKV infection.

Spike proteins of novel MERS-coronavirus isolates from North- and West-African dromedary camels mediate robust viral entry into human target cells

The highly pathogenic Middle East respiratory syndrome (MERS)-related coronavirus (CoV) is transmitted from dromedary camels, the natural reservoir, to humans. For at present unclear reasons, MERS cases have so far only been observed in the Arabian Peninsula, although MERS-CoV also circulates in African dromedary camels. A recent study showed that MERS-CoV found in North/West- (Morocco) and West-African (Burkina Faso and Nigeria) dromedary camels are genetically distinct from Arabian viruses and have reduced replicative capacity in human cells, potentially due to amino acid changes in one or more viral proteins. Here, we show that the spike (S) proteins of the prototypic Arabian MERS-CoV strain, human betacoronavirus 2c EMC/2012, and the above stated African MERS-CoV variants do not appreciably differ in expression, DPP4 binding and ability to drive entry into target cells. Thus, virus-host-interactions at the entry stage may not limit spread of North- and West-African MERS-CoV in human cells.

Entry of betaherpesviruses

In this chapter, we present an overview on betaherpesvirus entry, with a focus on human cytomegalovirus, human herpesvirus 6A and human herpesvirus 6B. Human cytomegalovirus (HCMV) is a complex human pathogen with a genome of 235kb encoding more than 200 genes. It infects a broad range of cell types by switching its viral ligand on the virion, using the trimer gH/gL/gO for infection of fibroblasts and the pentamer gH/gL/UL128/UL130/UL131 for infection of other cells such as epithelial and endothelial cells, leading to membrane fusion mediated by the fusion protein gB. Adding to this scenario, however, accumulating data reveal the actual complexity in the viral entry process of HCMV with an intricate interplay among viral and host factors. Key novel findings include the identification of entry receptors platelet-derived growth factor-α receptor (PDGFRα) and Netropilin-2 (Nrp2) for trimer and pentamer, respectively, the determination of atomic structures of the fusion protein gB and the pentamer, and the in situ visualization of the state and arrangement of functional glycoproteins on virion. This is covered in the first part of this review. The second part focusses on HHV-6 which is a T lymphotropic virus categorized as two distinct virus species, HHV-6A and HHV-6B based on differences in epidemiological, biological, and immunological aspects, although homology of their entire genome sequences is nearly 90%. HHV-6B is a causative agent of exanthema subitum (ES), but the role of HHV-6A is unknown. HHV-6B reactivation occasionally causes encephalitis in patients with hematopoietic stem cell transplant. The HHV-6 specific envelope glycoprotein complex, gH/gL/gQ1/gQ2 is a viral ligand for the entry receptor. Recently, each virus has been found to recognize a different cellular receptor, CD46 for HHV 6A amd CD134 for HHV 6B. These findings show that distinct receptor recognition differing between both viruses could explain their different pathogenesis.

Comparative analysis of viral entry for Asian and African lineages of Zika virus

Zika virus (ZIKV) is an emerging pathogen with global health and economic impacts. ZIKV circulates as two major lineages, Asian or African. The Asian lineage has recently been associated with significant disease in humans. Numerous studies have revealed differences between African and Asian ZIKV strains with respect to cellular infectivity, pathogenesis, and immune activation. Less is known about the mechanism of ZIKV entry and whether viral entry differs between strains. Here, we characterized ZIKV entry with two Asian and two African strains. All viruses exhibited a requirement for clathrin-mediated endocytosis and Rab5a function. Additionally, all ZIKV strains tested were sensitive to pH in the range of 6.5-6.1 and were reliant on endosomal acidification for infection. Finally, we provide direct evidence that ZIKV primarily fuses with late endosomes. These findings contribute new insight into the ZIKV entry process and suggest that divergent ZIKV strains enter cells in a highly conserved manner.

miRNAs and their roles in KSHV pathogenesis

Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiological agent of Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman Disease (MCD). Recent mechanistic advances have discerned the importance of microRNAs in the virus-host relationship. KSHV has two modes of replication: lytic and latent phase. KSHV entry into permissive cells, establishment of infection, and maintenance of latency are contingent upon successful modulation of the host miRNA transcriptome. Apart from host cell miRNAs, KSHV also encodes viral miRNAs. Among various cellular and molecular targets, miRNAs are appearing to be key players in regulating viral pathogenesis. Therefore, the use of miRNAs as novel therapeutics has gained considerable attention as of late. This innovative approach relies on either mimicking miRNA species by identical oligonucleotides, or selective silencing of miRNA with specific oligonucleotide inhibitors. Here, we provide an overview of KSHV pathogenesis at the molecular level with special emphasis on the various roles miRNAs play during virus infection.

Entry of sapelovirus into IPEC-J2 cells is dependent on caveolae-mediated endocytosis

BACKGROUND

Porcine sapelovirus (PSV), a species of the genus Sapelovirus within the family Picornaviridae, are a significant cause of enteritis, pneumonia, polioencephalomyelitis and reproductive disorders in pigs. However, the life cycle of PSV on the molecular level is largely unknown.

METHODS

Here, we used chemical inhibitors, RNA interference, and overexpression of dominant negative (DN) mutant plasmids to verify the roles of distinct endocytic pathways involved in PSV entry into porcine small intestinal epithelial cell line (IPEC-J2).

RESULTS

Our experiments indicated that PSV infection was inhibited when cells were pre-treated with NH₄Cl or chloroquine. Inhibitors nystatin, methyl-β-cyclodextrin, dynasore and wortmannin dramatically reduced PSV entry efficiency, whereas the inhibitors chlorpromazine and EIPA had no effect. Furthermore, overexpression caveolin DN mutant and siRNA against caveolin also decreased virus titers and VP1 protein synthesis, whereas overexpression EPS15 DN mutant and siRNA against EPS15 did not reduce virus infection.

CONCLUSIONS

Our findings suggest that PSV entry into IPEC-J2 cells depends on caveolae/lipid raft mediated-endocytosis, that is pH-dependent and requires dynamin and PI3K but is independent of clathrin and macropinocytosis.

A new strategy to identify hepatitis B virus entry inhibitors by AlphaScreen technology targeting the envelope-receptor interaction

Current anti-hepatitis B virus (HBV) agents have limited effect in curing HBV infection, and thus novel anti-HBV agents with different modes of action are in demand. In this study, we applied AlphaScreen assay to high-throughput screening of small molecules inhibiting the interaction between HBV large surface antigen (LHBs) and the HBV entry receptor, sodium taurocholate cotransporting polypeptide (NTCP). From the chemical screening, we identified that rapamycin, an immunosuppressant, strongly inhibited the LHBs-NTCP interaction. Rapamycin inhibited hepatocyte infection with HBV without significant cytotoxicity. This activity was due to impaired attachment of the LHBs preS1 domain to cell surface. Pretreatment of target cells with rapamycin remarkably reduced their susceptibility to preS1 attachment, while rapamycin pretreatment to preS1 did not affect its attachment activity, suggesting that rapamycin targets the host side. In support of this, a surface plasmon resonance analysis showed a direct interaction of rapamycin with NTCP. Consistently, rapamycin also prevented hepatitis D virus infection, whose entry into cells is also mediated by NTCP. We also identified two rapamycin derivatives, everolimus and temsirolimus, which possessed higher anti-HBV potencies than rapamycin. Thus, this is the first report for application of AlphaScreen technology that monitors a viral envelope-receptor interaction to identify viral entry inhibitors.

In vitro methods for testing antiviral drugs

Despite successful vaccination programs and effective treatments for some viral infections, humans are still losing the battle with viruses. Persisting human pandemics, emerging and re-emerging viruses, and evolution of drug-resistant strains impose continuous search for new antiviral drugs. A combination of detailed information about the molecular organization of viruses and progress in molecular biology and computer technologies has enabled rational antivirals design. Initial step in establishing efficacy of new antivirals is based on simple methods assessing inhibition of the intended target. We provide here an overview of biochemical and cell-based assays evaluating the activity of inhibitors of clinically important viruses.

Infection by Zika viruses requires the transmembrane protein AXL, endocytosis and low pH

The recent Zika virus (ZIKV) outbreak in Brazil has suggested associations of this virus infection with neurological disorders, including microcephaly in newborn infants and Guillian-Barré syndrome in adults. Previous reports have shown that AXL, a transmembrane receptor tyrosine kinase protein, is essential for ZIKV infection of mammalian cells, but this remains controversial. Here, we have assessed the involvement of AXL in the ability of ZIKV to infect mammalian cells, and also the requirement for endocytosis and acidic pH. We demonstrated that AXL is essential for ZIKV infection of human fibroblast cell line HT1080 as the targeted deletion of the gene for AXL in HT1080 cells made them no longer susceptible to ZIKV infection. Our results also showed that infection was prevented by lysosomotropic agents such as ammonium chloride, chloroquine and bafilomycin A1, which neutralize the normally acidic pH of endosomal compartments. Infection by ZIKV was also blocked by chlorpromazine, indicating a requirement for clathrin-mediated endocytosis. Taken together, our findings suggest that AXL most likely serves as an attachment factor for ZIKV on the cell surface, and that productive infection requires endocytosis and delivery of the virus to acidified intracellular compartments.

Cholesterol of lipid rafts is a key determinant for entry and post-entry control of porcine rotavirus infection

Background

Lipid rafts are major structural components in plasma membranes that play critical roles in many biological processes including virus infection. However, few reports have described the relationship between lipid rafts and porcine rotavirus (PRV) infection. In this study, we investigated whether or not the locally high concentrations (3–5 fold) of cholesterol present in lipid rafts are required for PRV infection, and further examined which stages of the infection process are most affected.

Results

When cellular cholesterol was depleted by methyl-β-cyclodextrin (MβCD), PRV infectivity significantly declined in a dose-dependent manner. This inhibition was partially reversed upon reintroduction of cholesterol into the system. This was corroborated by the co-localization of PRV with a recombinant, GPI-anchored green fluorescent protein, which functioned as a marker for membranous regions high in cholesterol and indicative of lipid rafts. Changes in virus titer and western blot analyses indicated that depletion of cellular cholesterol with MβCD had no apparent effect on PRV adsorption; however, depletion of cholesterol significantly restricted entry and post-entry of PRV into the cell. Both points of inhibition were restored to near normal levels by the addition of exogenous cholesterol.

Conclusions

We conclude from these studies that membrane-based cholesterol and in particular that localized to lipid rafts, is an indispensable biomolecule for PRV infection, and that cholesterol-based control of the infection process takes place during entry and immediately post-entry into the cell.

Glycoproteins of HHV-6A and HHV-6B

Recently, human herpesvirus 6A and 6B (HHV-6A and HHV-6B) were classified into distinct species. Although these two viruses share many similarities, cell tropism is one of their striking differences, which is partially because of the difference in their entry machinery. Many glycoproteins of HHV-6A/B have been identified and analyzed in detail, especially in their functions during entry process into host cells. Some of these glycoproteins were unique to HHV-6A/B. The cellular factors associated with these viral glycoproteins (or glycoprotein complex) were also identified in recent years. Detailed interaction analyses were also conducted, which could partially prove the difference of entry machinery in these two viruses. Although there are still issues that should be addressed, all the knowledges that have been earned in recent years could not only help us to understand these viruses' entry mechanism well but also would contribute to the development of the therapy and/or prophylaxis methods for HHV-6A/B-associated diseases.

The Role of HSV Glycoproteins in Mediating Cell Entry

The successful entry of herpes simplex virus (HSV) into a cell is a complex process requiring the interaction of several surface viral glycoproteins with host cell receptors. These viral glycoproteins are currently thought to work sequentially to trigger fusogenic activity, but the process is complicated by the fact that each glycoprotein is known to interact with a range of target cell surface receptor molecules. The glycoproteins concerned are gB, gD, and gH/gL, with at least four host cell receptor molecules known to bind to gB and gD alone. Redundancy among gD receptors is also evident and binding to both the gB and gD receptors simultaneously is known to be required for successful membrane fusion. Receptor type and tissue distribution are commonly considered to define the extent of viral tropism and thus the magnitude of pathogenesis. Viral entry receptors are therefore attractive pharmaceutical target molecules for the prevention and/or treatment of viral infections. However, the large number of HSV glycoprotein receptors makes a comprehensive understanding of HSV pathogenesis in vivo difficult. Here we summarize our current understanding of the various HSV glycoprotein cell surface receptors, define their redundancy and binding specificity, and discuss the significance of these interactions for viral pathogenesis.

Entry and Deposit of Aluminum in the Brain

Aluminum, as a known neurotoxicant, contributes to cognitive dysfunction and may contribute to Alzheimer's disease. The important reason is that aluminum can enter and be deposited in the brain. There have been three routes by which aluminum could enter the brain from systemic circulation or the site of absorption. Aluminum fluxes into brain across the blood-brain barrier (BBB), the choroid plexuses and the nasal cavity. Some factors, such as the increasing of the blood-brain barrier permeability, citric acid and parathyroid hormone (PTH), and vitamin D, can promote aluminum to enter the brain. But the redistribution of aluminum out of the brain is slow, so aluminum can be deposited in the brain for a long time.

Wild-type human coronaviruses prefer cell-surface TMPRSS2 to endosomal cathepsins for cell entry

Human coronaviruses (HCoVs) enter cells via two distinct pathways: the endosomal pathway using cathepsins to activate spike protein and the cell-surface or early endosome pathway using extracellular proteases such as transmembrane protease serine 2 (TMPRSS2). We previously reported that clinical isolates of HCoV-229E preferred cell-surface TMPRSS2 to endosomal cathepsin for cell entry, and that they acquired the ability to use cathepsin L by repeated passage in cultured cells and were then able to enter cells via the endosomal pathway. Here, we show that clinical isolates of HCoV-OC43 and -HKU1 preferred the cell-surface TMRRSS2 to endosomal cathepsins for cell entry, similar to HCoV-229E. In addition, the cell-culture-adapted HCoV-OC43 lost the ability to infect and replicate in air-liquid interface cultures of human bronchial tracheal epithelial cells. These results suggest that circulating HCoVs in the field generally use cell-surface TMPRSS2 for cell entry, not endosomal cathepsins, in human airway epithelial cells.

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Clinical isolates of HCoV-OC43 and -HKU1 were isolated from ALI-cultured HBTE cells.

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Clinical isolates of HCoVs preferred the TMRRSS2 to cathepsins for cell entry.

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Cell culture adapted HCoV-OC43 lost the ability to replicate in HBTE-ALI culture.

Development and characterization of a human monoclonal antibody targeting the N-terminal region of hepatitis C virus envelope glycoprotein E1

Monoclonal antibodies (mAbs) targeting the hepatitis C virus (HCV) envelope have been raised mainly against envelope protein 2 (E2), while the antigenic epitopes of envelope protein 1 (E1) are not fully identified. Here we describe the detailed characterization of a human mAb, designated A6, generated from an HCV genotype 1b infected patient. ELISA results showed reactivity of mAb A6 to full-length HCV E1E2 of genotypes 1a, 1b and 2a. Epitope mapping identified a region spanning amino acids 230-239 within the N-terminal region of E1 as critical for binding. Antibody binding to this epitope was not conformation dependent. Neutralization assays showed that mAb A6 lacks neutralizing capacity and does not interfere with the activity of known neutralizing antibodies. In summary, mAb A6 is an important tool to study the structure and function of E1 within the viral envelope, a crucial step in the development of an effective prophylactic HCV vaccine.

Owl monkey CCR5 reveals synergism between CD4 and CCR5 in HIV-1 entry

Studying HIV-1 replication in the presence of functionally related proteins from different species has helped define host determinants of HIV-1 infection. Humans and owl monkeys, but not macaques, encode a CD4 receptor that permits entry of transmissible HIV-1 variants due to a single residue difference. However, little is known about whether divergent CCR5 receptor proteins act as determinants of host-range. Here we show that both owl monkey (Aotus vociferans) CD4 and CCR5 receptors are functional for the entry of transmitted HIV-1 when paired with human versions of the other receptor. By contrast, the owl monkey CD4/CCR5 pair is generally a suboptimal receptor combination, although there is virus-specific variation in infection with owl monkey receptors. Introduction of the human residues 15Y and 16T within a sulfation motif into owl monkey CCR5 resulted in a gain of function. These findings suggest there is cross-talk between CD4 and CCR5 involving the sulfation motif.

The relationship between the umbilicus and the aortic bifurcation in Turkish women: implications for laparoscopic entry

PURPOSE

We aimed to determine the location and vertical distance of the umbilicus relative to the aortic bifurcation using computed tomography (CT), and assess their relationship with BMI among Turkish women and their implications for laparoscopic entry.

METHODS

This cross-sectional study included a total of 209 women undergoing abdominopelvic CT; the vertical distance between the aortic bifurcation and the umbilicus was evaluated on coronal sections. The distance between the skin and the parietal peritoneum was measured from the umbilical pit to the peritoneum, and the distance between the skin and the aorta was measured from the umbilical pit to the surface of the aortic bifurcation. The measurements were performed along the sagittal plane. The age, height, and weight of the patients were recorded. For comparison, women were divided into three groups according to BMI.

RESULTS

The aortic bifurcation was located above (cephalic to) the umbilicus in 30 patients in the non-obese group (48.4%), 54 patients in the overweight group (55.7%), and 34 patients (68%) in the obese group. The mean distances between the umbilicus and the parietal peritoneum were 15.1 ± 6.4, 19 ± 5.5, 27.2 ± 10.8 mm, respectively, in the non-obese group, overweight group, and obese group. The mean distances between the umbilicus and the aorta were 85.8 ± 26.3, 110 ± 2.9, 132.1 ± 26.7 mm, respectively, in the non-obese group, overweight group, and obese group.

CONCLUSIONS

The location of the umbilicus relative to the aortic bifurcation can vary according to age, BMI and ethnicity or nationality of patients; therefore, a surgeon should not stick to a particular angle of insertion during laparoscopic entry. It is better for surgeons to know their unique patient population.

Maturation of secreted HCV particles by incorporation of secreted ApoE protects from antibodies by enhancing infectivity

BACKGROUND & AIMS

Hepatitis C virus (HCV) evades humoral immunity and establishes chronic infections. Virus particles circulate in complex with lipoproteins facilitating antibody escape. Apolipoprotein E (ApoE) is essential for intracellular HCV assembly and for HCV cell entry. We aimed to explore if ApoE released from non-infected cells interacts with and modulates secreted HCV particles.

METHODS

ApoE secreted from non-infected cells was incubated with HCV from primary human hepatocytes or Huh-7.5 cells. Co-immunoprecipitation, viral infectivity and neutralization experiments were conducted.

RESULTS

Physiological levels of secreted ApoE (10-60µg/ml) enhanced the infectivity of HCV up to 8-fold across all genotypes, which indirectly decreased virus neutralization by antibodies targeting E1 or E2 up to 10-fold. Infection enhancement was observed for particles produced in primary human hepatocytes and Huh-7.5 cells. Selective depletion of ApoE ablated infection enhancement. Addition of HA-tagged ApoE to HCV particles permitted co-precipitation of HCV virions. Serum ApoE levels ranged between 10-60µg/ml, which is ca 100-fold higher than in Huh-7.5 conditioned cell culture fluids. Serum-derived HCV particles carried much higher amounts of ApoE than cell culture-derived HCV particles. Serum ApoE levels correlated with efficiency of co-precipitation of HCV upon exogenous addition of HA-ApoE. ApoE-dependent infection enhancement was independent of the hypervariable region 1 and SR-B1, but was dependent on heparan sulfate proteoglycans (HSPGs).

CONCLUSIONS

Physiological quantities of secreted ApoE stimulate HCV infection and increase antibody escape, by incorporating into virus particles and enhancing particle interactions with cellular HSPGs. Thus, secreted particles undergo ApoE-dependent maturation to enhance infectivity and to facilitate evasion from neutralizing antibodies. Lay summary: This study shows that HCV particle infectivity is remodeled by secreted ApoE after particle release from cells. Fluctuation of the availability of ApoE likely influences HCV infectivity, antibody escape and transmission.

Forty Years of Ebolavirus Molecular Biology: Understanding a Novel Disease Agent Through the Development and Application of New Technologies

Molecular biology is a broad discipline that seeks to understand biological phenomena at a molecular level, and achieves this through the study of DNA, RNA, proteins, and/or other macromolecules (e.g., those involved in the modification of these substrates). Consequently, it relies on the availability of a wide variety of methods that deal with the collection, preservation, inactivation, separation, manipulation, imaging, and analysis of these molecules. As such the state of the art in the field of ebolavirus molecular biology research (and that of all other viruses) is largely intertwined with, if not driven by, advancements in the technical methodologies available for these kinds of studies. Here we review of the current state of our knowledge regarding ebolavirus biology and emphasize the associated methods that made these discoveries possible.