Penetration and Antiviral Activity of Coxsackievirus B3 (Cvb3)-Specific Phosphorothioate Oligodeoxynucleotides (Ps-Odn)

Antiviral activity of some benzo[g]quinazolines against coxsackievirus B4: biological screening and docking study

BACKGROUND

Serotype coxsackievirus B (CVB) infection has been linked to viral myocarditis, dilated cardiomyopathy, meningitis, and pancreatitis in children and young adults. As of yet, no antiviral drug has been authorized for the treatment of coxsackievirus infection. Therefore, there is perpetual demand for new therapeutic agents and the improvement of existing ones. Benzo[g]quinazolines, the subject of several well-known heterocyclic systems, have risen to prominence and played a significant role in the development of antiviral agents, particularly those for anti-coxsackievirus B4 infection.

METHODS

This study investigated the cytotoxicity of the target benzo[g]quinazolines (1-16) in the BGM cells line as well as their anti-coxsackievirus B4 activity. Determination of CVB4 titers using a plaque assay.

RESULTS

Most of the target benzoquinazolines exhibited antiviral activity, however, compounds 1-3 appeared to be the most effective (reduction percentages of 66.7, 70, and 83.3%, respectively). The binding mechanisms and interactions of the three most active 1-3 with the constitutive amino acids in the active site of the multi-target of coxsackievirus B4 (3Clpro and RdRp) targets were also investigated using molecular docking.

CONCLUSION

The anti coxsackievirus B4 activity has resulted, and the top three active benzoquinazolines (1-3) have bonded to and interacted with the constitutive amino acids in the active region of the multi-target coxsackievirus B4 (RdRp and 3Clpro). Further research is required in the lab. to determine the exact benzoquinazolines mechanism of action.

Biological Investigation of 2-Thioxo-benzo[g]quinazolines against Adenovirus Type 7 and Bacteriophage Phi X174: An In Vitro Study

Mortality and morbidity caused by viruses are a global health problems. Therefore, there is always a need to create novel therapeutic agents and refine existing ones to maximize their efficacy. Our lab has produced benzoquinazolines derivatives that have proven effective activity as antiviral compounds against herpes simplex (HSV 1 and 2), coxsackievirus B4 (CVB4), and hepatitis viruses (HAV and HCV). This in vitro study was aimed at investigating the effectiveness of benzoquinazoline derivatives 1-16 against adenovirus type 7 and bacteriophage phiX174 using a plaque assay. The cytotoxicity against adenovirus type 7 was also performed in vitro, using a MTT assay. Most of the compounds exhibited antiviral activity against bacteriophage phiX174. However, compounds 1, 3, 9, and 11 showed statistically significant reductions of 60-70% against bacteriophage phiX174. By contrast, compounds 3, 5, 7, 12, 13, and 15 were ineffective against adenovirus type 7, and compounds 6 and 16 had remarkable efficacy (50%). Using the MOE-Site Finder Module, a docking study was carried out in order to create a prediction regarding the orientation of the lead compounds (1, 9, and 11). This was performed in order to investigate the activity of the lead compounds 1, 9, and 11 against the bacteriophage phiX174 by locating the ligand-target protein binding interaction active sites.

Evaluation of Some Benzo[g]Quinazoline Derivatives as Antiviral Agents against Human Rotavirus Wa Strain: Biological Screening and Docking Study

Globally, rotavirus (RV) is the most common cause of acute gastroenteritis in infants and toddlers; however, there are currently no agents available that are tailored to treat rotavirus infection in particular. Improved and widespread immunization programs are being implemented worldwide to reduce rotavirus morbidity and mortality. Despite certain immunizations, there are no licensed antivirals that can attack rotavirus in hosts. Benzoquinazolines, chemical components synthesized in our laboratory, were developed as antiviral agents, and showed good activity against herpes simplex, coxsackievirus B4 and hepatitis A and C. In this research project, an in vitro investigation of the effectiveness of benzoquinazoline derivatives 1–16 against human rotavirus Wa strains was carried out. All compounds exhibited antiviral activity, however compounds 1–3, 9 and 16 showed the greatest activity (reduction percentages ranged from 50 to 66%). In-silico molecular docking of highly active compounds, which were selected after studying the biological activity of all investigated of benzo[g]quinazolines compounds, was implemented into the protein’s putative binding site to establish an optimal orientation for binding. As a result, compounds 1, 3, 9, and 16 are promising anti-rotavirus Wa strains that lead with Outer Capsid protein VP4 inhibition.

Novel Thiophene Thioglycosides Substituted with the Benzothiazole Moiety: Synthesis, Characterization, Antiviral and Anticancer Evaluations, and NS3/4A and USP7 Enzyme Inhibitions

Novel derivatives of benzothiazole-2-thiophene S-glycoside were synthesized and tested for their antiviral and anticancer potency and NS3/4A and USP7 enzyme inhibitions. The ring system was formed by first synthesizing new derivatives of 5-mercaptothiophene substituted with the benzothiazole moiety, followed by coupling with various halo sugar derivatives. New compounds were tested in vitro for the cytotoxic effect on five types of normal cell lines and for antiviral activity using a plaque reduction assay against CBV4, HSV-1, HCVcc genotype 4 viruses, HAV HM 175, and HAdV7. Notably, three compounds demonstrated substantial IC₅₀, CC₅₀, and SI values against HSV-1 with a viral reduction of 80% or more. Two substances have demonstrated a reduction of more than 50% in CBV4 and HCVcc viruses. The effectiveness of the compounds against HSV-1 and HCVcc was tested for their capability to inhibit NS3/4A protease and USP7 enzyme. Additionally, a panel of 60 human cancer cells was used to investigate the ability of the newly synthesized compounds to inhibit the in vitro tumor growth. The results revealed that two compounds, 6a and 6c, have an inhibitory effect on most cancer types, whereas 6d and 6f inhibited only three and two cell lines, respectively.

Thermal Inactivation of Hepatitis A Virus, Noroviruses, and Simian Rotavirus in Cows' Milk

Consumption of raw or unpasteurized milk is a risk for the consumers because indirect contaminations such as fecal-cross-contamination could occur and determine the presence of enteric viruses. In this study, milk was treated with several temperature and time combinations chosen by performing a preliminary experiment to evaluate the intervals needed to inactivate Hepatitis A virus (HAV) HM175 strain, noroviruses genogroups I and II (GI and GII), and simian rotavirus SA11 at different temperatures. Results were obtained by measuring the genome copies and infectious units by real-time PCR and plaque assays respectively. At 85 °C, one minute and two minutes were needed to achieve 6.6 log₁₀ ± 0.2 and 8 log₁₀ ± 0 reductions of genome copies of HAV respectively. Similar genome copies reduction was also observed for noroviruses (GI and GII) and simian rotavirus. At higher temperatures, 90 s (s) at 90 °C and 60 s at 95 °C were needed to achieve 8 log₁₀ ± 0 reductions of the genome copies of all studied viruses. Significant higher sensitivity of the infectious units of both HAV and simian rotavirus to heat treatment of milk than their genome copies was observed. At boiling point of milk (100.5 °C), 40 s were needed to achieve 8 log₁₀ ± 0 reductions of genome copies of all the studied viruses, while 10 s were needed to achieve 6 log₁₀ ± 0 reductions of the infectious units of HAV and simian rotavirus. Significant higher reduction of infectious units than genome copies was observed confirming that genome copies reduction does not correspond to infectious virus.

Novel Synthesis and Antiviral Evaluation of New Benzothiazole-Bearing N-Sulfonamide 2-Pyridone Derivatives as USP7 Enzyme Inhibitors

In this article, a series of benzothiazole-bearing N-sulfonamide 2-pyridone derivatives were synthesized via the reaction of benzothiazole sulfonylhydrazide with sodium salts of both (hydroxymethylene) cycloalkanones and unsaturated ketones, as well as ethoxymethylene derivatives. The structures of the resultant compounds were confirmed using IR, ¹H NMR, ¹³C NMR, ¹H-¹H correlation spectroscopy (COSY), ¹H-¹³C heteronuclear multiple bond coherence (HMBC), and ¹H-¹³C heteronuclear multiple quantum coherence (HSQC) spectral analysis and elemental analysis. The newly synthesized compounds were evaluated in vitro for their antiviral activities against the HSV-1, HAV HM175, HCVcc genotype 4, CBV4, and HAdV7 viruses. Additionally, the compounds were examined for their cytotoxic effect on five normal cell lines. It was observed that five compounds were found to possess viral reduction of 50% or more against CBV4 with significant IC₅₀, CC₅₀, and SI values. In the case of HSV-1 and HAV HM175 viruses, three compounds have shown more than 50% reduction, while in the case of HCVcc genotype 4 and HAdV7 viruses, only two compounds demonstrated more than 50% reduction. Furthermore, the physicochemical properties of the most active compounds were evaluated. The two most potent compounds against HSV-1 virus, 7e and 13a, were evaluated for their inhibitory activity against USP7. Docking studies using Molecular Operating Environment (MOE) were used to identify the interactions between 7e and 13a compounds and the active site of the USP7 enzyme.

Design and Synthesis of a New Class of Pyridine-Based N-Sulfonamides Exhibiting Antiviral, Antimicrobial, and Enzyme Inhibition Characteristics

A new strategy for designing and assembling a novel class of functionalized pyridine-based benzothiazole and benzimidazole incorporating sulfonamide moieties was developed. The synthesis was carried out by reacting N-cyanoacetoarylsulfonylhydrazide with various electrophiles such as 2-(benzo[d]thiazol-2-yl)-3,3-bis(alkylthio)acrylonitriles and 2-(benzo[d]imidazol-2-yl)-3,3-bis(methylthio)-acrylonitriles, as well as 2-ethoxyl acrylonitrile derivatives. The synthesized compounds were tested for their antiviral and antimicrobial potency. Two of the synthesized compounds, 15c and 15d, showed more than 50% viral reduction against HSV-1 and CBV4, with significant IC₅₀ and CC₅₀ values. The two potent compounds 15c and 15d have also shown inhibitory activity against Hsp90α protein with IC₅₀ values of 10.24 and 4.48 μg/mL, respectively. A combination of 15c and 15d with acyclovir has led to IC₅₀ values that are lower than that of acyclovir alone. Molecular modeling studies were used to identify the interactions between the 15c and 15d compounds and the active site of Hsp90α enzyme. The antimicrobial investigation of the new compounds has also shown that 8b and 15d exhibited a higher inhibition zone (IZ) than sulfadiazine and gentamicin against Klebsiella pneumonia, whereas 9a showed higher IZ than ampicillin against Staphylococcus aureus. According to the enzyme assay study on dihydrofolate reductase, 9a was shown to be the most potent compound among all examined compounds.

Sofosbuvir Thio-analogues: Synthesis and Antiviral Evaluation of the First Novel Pyridine- and Pyrimidine-Based Thioglycoside Phosphoramidates

The synthesis and antiviral screening of the first reported series of pyridine- and pyrimidine-based thioglycoside phosphoramidates are herein reported. They were prepared through two synthetic steps: The first step is via coupling of mercapto-derivatized heterocyclic bases with the appropriate α-bromo per-acetylated sugars. The second one is the hydrolysis of the acetate esters under basic conditions that were consequently conjugated with the phosphoramidating reagent to afford the desired thioglycoside protides. Eight compounds were evaluated for their antiviral activities against different viral cell lines, namely, adenovirus 7, HAV (hepatitis A) HM175, Coxsackievirus B4, and HSV-1 (herpes simplex virus type 1), in addition to the antiviral bioassay against ED-43/SG-Feo (VYG) replicon of HCV (hepatitis C virus) genotype 4a. Both compounds 5b and 11 showed notable antiviral activity against Coxsackie virus B4, reflected from the CC₅₀ values of 17 and 20 μg/100 μL and IC₅₀ values of 4.5 and 6.0 μg/100 μL, respectively. Same two compounds elicited remarkable activities toward herpes simplex virus type 1, represented by CC₅₀ values of 17 and 16 μg/100 μL and IC₅₀ values of 6.3 and 6.6 μg/100 μL, respectively. Combination of 11 with acyclovir elicited a notable synergistic activity in comparison with acyclovir alone, as inferred from herpes simplex polymerase enzyme inhibitory assay values of 2.64 and 4.78 μg/100 mL, respectively. Only compound 11 elicited a remarkable activity against HCV. Potential promising activities of compound 11 have been shown with respect to CC₅₀, IC₅₀, and enzyme assay inhibitory activities.

New 2-Oxopyridine/2-Thiopyridine Derivatives Tethered to a Benzotriazole with Cytotoxicity on MCF7 Cell Lines and with Antiviral Activities

Background:

Perturbation of nucleic acids structures and confirmation by small molecules through intercalation binding is an intriguing application in anticancer therapy. The planar aromatic moiety of anticancer agents was inserted between DNA base pairs leading to change in the DNA structure and subsequent functional arrest.

Objective:

The final scaffold of the target compounds was annulated and linked to a benzotriazole ring. These new pharmacophoric features were examined as antiviral and anticancer agents against MCF7 and their effect on DNA damage was also assessed.

Methods:

A new series of fully substituted 2-oxopyridine/2-thioxopyridine derivatives tethered to a benzotriazole moiety (4a-h) was synthesized through Michael cyclization of synthesized α,β- unsaturated compounds (3a-e) with appropriate active methylene derivatives. The DNA damage study was assessed by comet assay. In silico DNA molecular docking was performed using Open Eye software to corroborate the experimental results and to understand molecule interaction at the atomic level.

Results:

The highest DNA damage was observed in Doxorubicin, followed by 4h, then, 4b, 4g, 4f, 4e, and 4d. The docking study showed that compound 4h formed Hydrogen Bonds (HBs) as a standard ligand with GSK-3. Compound 4h was the most active compound against rotavirus Wa, HAVHM175, and HSV strains with a reduction of 30%, 40%, and 70%, respectively.

Conclusion:

Compound 4h was the most active compound and could act as a prospective lead molecule for anticancer agent.

Efficient Synthesis and Docking Studies of Novel Benzothiazole-Based Pyrimidinesulfonamide Scaffolds as New Antiviral Agents and Hsp90α Inhibitors

A series of novel substituted 2-pyrimidylbenzothiazoles incorporating either sulfonamide moieties or the amino group at C2 of the pyrimidine ring were synthesized and evaluated for its antiviral potency. The novel synthesis of the ring system was carried out by reacting guanidine or N-arylsulfonated guanidine with different derivatives of ylidene benzothiazole based on Michael addition pathways. The antiviral activity of the newly synthesized compounds was examined by a plaque reduction assay against HSV-1, CBV4, HAV HM 175, HCVcc genotype 4 viruses, and HAdV7. In the case of HSV-1, it was determined that 5 out of the 21 synthesized compounds exhibited superior viral reduction in the range of 70-90% with significant IC₅₀, CC₅₀, and SI values as compared with acyclovir. In the case of CBV4, nine compounds have shown more than 50% reduction. Comparable results were obtained for seven of these synthesized compounds when evaluated against HAV with only a couple of them showing 50% reduction or more against HCVcc genotype 4. Remarkably, one compound, 9a, has shown broad action against all five examined viruses, rendering it as potentially an effective antiviral agent. The five potent compounds 9a, 9b, 14b, 14g, and 14h against HSV-1 have also presented inhibitory activity against the Hsp90α protein with IC₅₀ in the range of 4.87-10.47 μg/mL. Interestingly, a combination of the potent synthesized compounds with acyclovir led to IC₅₀ values lower than that of acyclovir alone. The potent compounds 9a, 9b, 14b, 14g, and 14h were also docked inside the active site of Hsp90α to assess the interaction pattern between the tested compounds and the active site of the protein.

Evaluation of novel pyrrolopyrimidine derivatives as antiviral against gastroenteric viral infections

Viral gastroenteritis is a major global public-health threat. All age groups are susceptible for this infection, but its most serious consequences affect children. Rotavirus, Coxsackievirus and Adenovirus are the most common viruses that cause gastroenteritis. Herein, we synthesized novel pyrrole, pyrrolo[2,3‑d]pyrimidine and pyrrolo[3,2‑e][1,2,4]triazolo[4,3‑c]pyrimidine derivatives. The non-toxic doses of these compounds were determined using BGM cell lines. We examined all the new compounds for their anti-viral activities against Rotavirus Wa strain and Coxsackievirus B4. Compounds 2a, 2d, 5a, 5c, 5d, 7b, 7j, 7n, 14b, 14c, 14e and 14f exhibited significant antiviral activity. We interpreted the action of these compounds using molecular docking against the homology models of viral polymerase enzymes of these viruses. RMSD value of 5d/Coxsackievirus was higher than the RMSD value for 5d/rotavirus and hence better as a stability parameter, which can be correlated to the biological activity.

Coxsackievirus B4 as a Causative Agent of Diabetes Mellitus Type 1: Is There a Role of Inefficiently Treated Drinking Water and Sewage in Virus Spreading?

This study proposed to detect the enterovirus (EV) infection in children with type 1 diabetes mellitus (T1D) and to assess the role of insufficiently treated water and sewage as sources of viral spreading. Three hundred and eighty-two serum specimens of children with T1D, one hundred serum specimens of children who did not suffer from T1D as control, and forty-eight water and sewage samples were screened for EV RNA using nested RT-PCR. The number of genome copies and infectious units of EVs in raw and treated sewage and water samples were investigated using real-time (RT)-PCR and plaque assay, respectively. T1D markers [Fasting blood glucose (FBG), HbA1c, and C-peptide], in addition to anti-Coxsackie A & B viruses (CVs A & B) IgG, were measured in control, T1D-negative EV (T1D-EV^-), and T1D-positive EV (T1D-EV⁺) children specimens. The prevalence of EV genome was significantly higher in diabetic children (26.2%, 100 out of 382) than the control children (0%, 0 out of 100). FBG and HbA1c in T1D-EV^- and T1D-EV⁺ children specimens were significantly higher than those in the control group, while c-peptide in T1D-EV^- and T1D-EV⁺ children specimens was significantly lower than that in the control (n = 100; p < 0.001). Positivity of anti-CVs A & B IgG was 70.7, 6.7, and 22.9% in T1D-EV⁺, T1D-EV^-, and control children specimens, respectively. The prevalence of EV genome in drinking water and treated sewage samples was 25 and 33.3%, respectively. The prevalence of EV infectious units in drinking water and treated sewage samples was 8.5 and 25%, respectively. Quantification assays were performed to assess the capabilities of both wastewater treatment plants (WWTPs) and water treatment plants (WTPs) to remove EV. The reduction of EV genome in Zenin WWTP ranged from 2 to 4 log₁₀, while the reduction of EV infectious units ranged from 1 to 4 log₁₀. The reduction of EV genome in El-Giza WTP ranged from 1 to 3 log₁₀, while the reduction of EV infectious units ranged from 1 to 2 log₁₀. This capability of reduction did not prevent the appearance of infectious EV in treated sewage and drinking water. Plaque purification was performed for isolation of separate EV isolates from treated and untreated water and sewage samples. Characterization of the EV amplicons by RT-PCR followed by sequencing of these isolates revealed high homology (97%) with human coxsackievirus B4 (CV B4) in 60% of the isolates, while the rest of the isolates belonged to poliovirus type 1 and type 2 vaccine strains. On the other hand, characterization of the EV amplicons by RT-PCR followed by sequencing for T1D-EV⁺ children specimens indicated that all samples contained CV B4 with the same sequence characterized in the environmental samples. CV B4-contaminated drinking water or treated sewage may play a role as a causative agent of T1D in children.

Novel antiviral compounds against gastroenteric viral infections

Viral gastroenteritis is a serious viral infection which affects a large number of individuals around the world, most of them being children. The infection may occur due to different viruses, for example, coxsackievirus, adenovirus, and rotavirus. There is no available cure for such infections, and the treatment mainly depends on hospitalization and administration of nutritional supports. A new antiviral agent against gastroenteritis viral infection will be a breakthrough in healthcare. Pyrrole and pyrrolopyrimidine derivatives are well known for their biological activity as antibacterial, antifungal, and anticancer agents. These compounds also proved to possess antiviral activity. Here, we synthesized novel pyrrole and pyrrolopyrimidine compounds and examined their antiviral activity. We synthesized several new pyrrole, pyrrolo[2,3-d]pyrimidine, and pyrrolo[3,2-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives. The characterization of all synthesized compounds was based on microanalysis and spectral data. Moreover, we determined the non-toxic doses of these compounds on BGM, Hep-2, and MA-104 cells. We tested all the synthesized compounds for their antiviral activities against coxsackievirus B4, adenovirus type 7, and rotavirus Wa strain. Several compounds exhibited significant activities as antiviral agents.

Synthesis, antibacterial, and antiviral evaluation of new heterocycles containing the pyridine moiety

A facile one-pot four-component reaction was utilized to construct 2-oxo-1,2-dihydropyridine-3-carbonitrile as a scaffold for the synthesis of many fused heterocyclic systems, namely, furopyridine, pyridothiadiazepinthione, and pyridotriazine, as well as non-fused heterocyclic systems such as phthalazin-2(1H)-ylnicotinonitrile, pyridin-2-yl-1H-pyrazole, and pyrazol-1-ylnicotino-nitrile,1-(3-cyanopyridin-2-yl)-1H-pyrazole. The new compounds were evaluated as antimicrobial and antiviral agents.

Utilization of the embryonated egg for in vivo evaluation of the anti-influenza virus activity of neuraminidase inhibitors

Previous studies have shown that embryonated egg provides a convenient and easy to use system for in vivo screening of anti-influenza virus inhibitors. However, it is not known whether this model is suitable for testing neuraminidase (NA) inhibitors, too. Therefore, the present study describes the evaluation of the ion-channel blockers amantadine and rimantadine in comparison with the NA inhibitors oseltamivir and zanamivir by using the influenza A virus hen's egg model. The treatment was started immediately before or after the challenge dose was placed on the chorioallantoic membrane (CAM). Differences between the survival rate of treated and untreated chick embryos infected with influenza A virus were analyzed statistically. As result, the survival rate of chick embryos could be significantly increased when the treatment with amantadine, rimantadine, oseltamivir, or zanamivir was started before the CAM was inoculated with one egg infective dose 50% (EID50) influenza A virus. When the drugs were administered shortly after viral inoculation, significant antiviral efficacy was shown for rimantadine, oseltamivir, and zanamivir. Antiviral efficacy could be demonstrated exclusively for both oseltamivir and zanamivir after the embryos were infected with higher challenge doses of 10(2) EID50 influenza A virus. In conclusion, the NA inhibitors oseltamivir and zanamivir have a significantly better antiviral activity against influenza A virus than amantadine and rimantadine tested in embryonated hen's eggs. Therefore, this model can be a valuable alternative approach for in vivo pre-testing anti-influenza virus activity of NA inhibitors.

Evaluation of the anti-microbial and anti-inflammatory activities of the medicinal plants Dodonaea viscosa, Rumex nervosus and Rumex abyssinicus

The crude extracts of the leaves of Dodonaea viscosa and Rumex nervosus as well as of the root of Rumex abyssinicus were tested for anti-microbial and anti-inflammatory activities. It was observed that the three plants possess antibacterial activity against Streptococcus pyogenes and Staphylococcus aureus and strong activity against Coxsackie virus B3 and influenza A virus. In contrast, none of them exhibited anti-fungal activity. The anti-inflammatory activity test results verified that only R. abyssinicus inhibited the synthesis of prostaglandin (PG) E(2).

A rapid assay for evaluation of antiviral activity against coxsackie virus B3, influenza virus A, and herpes simplex virus type 1

In order to identify new potential antiviral drugs, small amounts of extracts or compounds have to be examined for cytotoxicity and antiviral activity in primary screening using a rapid, easy, inexpensive, and highly standardised test system. In this study, high-throughput cytopathic effect (CPE) inhibitory assays were established for coxsackie virus B3 on HeLa Ohio cells, influenza virus A on Madin-Darby canine kidney cells, and herpes simplex virus type 1 (HSV-1) on green monkey kidney cells that meet these requirements. The cytotoxic and the antiviral effects were quantified using a crystal violet uptake assay allowing automated handling of large numbers of candidate agents. To ensure comparable results with plaque reduction assays, the 50 and 90% plaque inhibitory concentrations of guanidine, amantadine, and phosphonoformic acid were used to standardise the anti-coxsackie virus B3, anti-influenza virus A, and anti-HSV-1 tests, respectively. The strong correlation between the antiviral activity determined by CPE-inhibitory assays and plaque reduction assay was further proved for other antivirals. In summary, low amounts of large numbers of compounds may be tested inexpensively and standardised within 24 h (coxsackie virus B3 and influenza virus A) or 48 h (herpes simplex virus type 1) post-infection using CPE inhibitory assays.

Attachment of coxsackievirus B3 variants to various cell lines: mapping of phenotypic differences to capsid protein VP1

The coxsackievirus B3 (CVB3) strain Nancy P establishes a persistent carrier-state infection without visible cytopathic effect in primary human fibroblasts (HuFi H), whereas the derivative variant PD induces a complete lysis of the cell monolayer. To define the molecular basis of this exceptional growth property, the complete genomes of both viruses were sequenced and compared to all published sequences of CVB3. As a result, six unique amino acid substitutions in the VP1 capsid protein were observed. Via hybrid virus construction, the lytic phenotype was transferred to a nonlytic cDNA-generated CVB3. Mapping experiments indicate that the presence of amino acid residues K78, A80, A91, and I92 in VP1 is sufficient to induce "lytic" infections in HuFi H cells. Binding assays demonstrate that CVB3 Nancy P preferentially binds to the human coxsackievirus-adenovirus receptor (CAR), while PD exhibits a very weak interaction with CAR but strong binding to the decay accelerating factor (DAF). These results suggest that the mutated amino acid residues in VP1 are involved in receptor recognition/binding. Moreover, the lytic replication of CVB3 PD and the hybrid virus in various nonpermissive rodent cell lines indicates that cell surface molecules other than CAR and DAF may be involved in attachment of this variant to cell surfaces.