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1.
J Med Virol ; 94(1): 147-153, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34411312

RESUMO

This study aimed to determine the frequency of SARS-CoV-2 RNA in serum and its association with the clinical severity of COVID-19. This retrospective cohort study performed at Toyama University Hospital included consecutive patients with confirmed COVID-19. The prevalence of SARS-CoV-2 RNAemia and the strength of its association with clinical severity variables were examined. Fifty-six patients were included in this study. RNAemia was detected in 19.6% (11/56) patients on admission, and subsequently in 1.0% (1/25), 50.0% (6/12), and 100.0% (4/4) moderate, severe, and critically ill patients, respectively. Patients with RNAemia required more frequent oxygen supplementation (90.0% vs. 13.3%), ICU admission (81.8% vs. 6.7%), and invasive mechanical ventilation (27.3% vs. 0.0%). Among patients with RNAemia, the median viral loads of nasopharyngeal (NP) swabs that were collected around the same time as the serum sample were significantly higher in critically ill (5.4 log10 copies/µl; interquartile range [IQR]: 4.2-6.3) than in moderate-severe cases (2.6 log10 copies/µl; [IQR: 1.1-4.5]; p = 0.030) and were significantly higher in nonsurvivors (6.2 log10 copies/µl [IQR: 6.0-6.5]) than in survivors (3.9 log10 copies/µl [IQR: 1.6-4.6]; p = 0.045). This study demonstrated a relatively high proportion of SARS-CoV-2 RNAemia and an association between RNAemia and clinical severity. Moreover, among the patients with RNAemia, the viral loads of NP swabs were correlated with disease severity and mortality, suggesting the potential utility of combining serum testing with NP tests as a prognostic indicator for COVID-19, with higher quality than each separate test.


Assuntos
COVID-19/virologia , Nasofaringe/virologia , RNA Viral/sangue , SARS-CoV-2/isolamento & purificação , Carga Viral , Viremia , Adolescente , Adulto , Idoso , COVID-19/mortalidade , COVID-19/fisiopatologia , Criança , Estado Terminal , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Retrospectivos , Índice de Gravidade de Doença , Adulto Jovem
2.
Microbiol Spectr ; : e0056121, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34851162

RESUMO

Vaccines against severe acute respiratory syndrome coronavirus-2 have been introduced. To investigate the relationship between vaccine-induced humoral immunity and patient age, we measured antibody levels and neutralization in vaccinated sera. Sera from 13 to 17 days after the second dose of the BNT162b2 vaccine were collected from health care workers at the University of Toyama (n = 740). Antibody levels were measured by the anti-receptor binding domain antibody test (anti-RBD test), and neutralization against wild-type (WT), α- and ß-variant pseudotyped viruses were assayed using a high-throughput chemiluminescent reduction neutralizing test (htCRNT; positivity cutoff, 50% neutralization at serum dilution 1:100). Basic clinical characteristics were obtained from questionnaires. Antibodies were confirmed in all participants in both the anti-RBD test (median, 2,112 U/ml; interquartile range [IQR], 1,275 to 3,390 U/ml) and the htCRNT against WT (median % inhibition, >99.9; IQR, >99.9 to >99.9). For randomly selected sera (n = 61), 100.0% had positive htCRNT values against the α- and ß-derived variants. Among those who answered the questionnaire (n = 237), the values of the anti-RBD test were negatively correlated with age in females (P < 0.01). An age-dependent decline in neutralization was observed against the variants but not against the wild-type virus (wild type, P = 0.09; α, P < 0.01; ß, P < 0.01). The neutralizing activity induced by BNT162b2 was obtained not only against the wild-type virus, but also against the variants; however, there was an age-dependent decrease in the latter. Age-related heterogeneity of vaccine-acquired immunity is a concern in preventive strategies in the era dominated by variants. IMPORTANCE Since mRNA vaccines utilize wild-type SARS-CoV-2 spike protein as an antigen, there are potential concerns about acquiring immunity to variants of this virus. The neutralizing activity in BNT162b2-vaccinated individuals was higher against the wild-type virus than against its variants; this effect was more apparent in older age groups. This finding suggests that one of the weaknesses of the mRNA vaccine is the high risk of variant infection in the elderly population. Because the elderly are at a higher risk of SARS-CoV-2 infection, the age-dependent decline of neutralization against viral variants should be considered while planning vaccination programs that include boosters.

3.
Microbiol Spectr ; : e0056021, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34851163

RESUMO

Serological tests are beneficial for recognizing the immune response against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). To identify protective immunity, optimization of the chemiluminescent reduction neutralizing test (CRNT) is critical. Whether commercial antibody tests have comparable accuracy is unknown. Serum samples were obtained from COVID-19 patients (n = 74), SARS-CoV-2 PCR-negative (n = 179), and suspected healthy individuals (n = 229) before SARS-CoV-2 variants had been detected locally. The convalescent phase was defined as the period after day 10 from disease onset or the episode of close contact. The CRNT using pseudotyped viruses displaying the wild-type (WT) spike protein and a commercial anti-receptor-binding domain (RBD) antibody test were assayed. Serology for the B.1.1.7 and B.1.351 variants was also assayed. Both tests concurred for symptomatic COVID-19 patients in the convalescent phase. They clearly differentiated between patients and suspected healthy individuals (sensitivity: 95.8% and 100%, respectively; specificity: 99.1% and 100%, respectively). Anti-RBD antibody test results correlated with neutralizing titers (r = 0.31, 95% confidence interval [CI] 0.22-0.38). Compared with the WT, lower CRNT values were observed for the variants. Of the samples with ≥100 U/mL by the anti-RBD antibody test, 77.8% and 88.9% showed ≥50% neutralization against the B.1.1.7 and the B.1.351 variants, respectively. Exceeding 100 U/mL in the anti-RBD antibody test was associated with neutralization of variants (P < 0.01). The CRNT and commercial anti-RBD antibody test effectively classified convalescent COVID-19 patients. Strong positive results with the anti-RBD antibody test can reflect neutralizing activity against emerging variants. IMPORTANCE This study provides a diagnostic evidence of test validity, which can lead to vaccine efficacy and proof of recovery after COVID-19. It is not easy to know neutralization against SARS-CoV-2 in the clinical laboratory because of technical and biohazard issues. The correlation of the quantitative anti-receptor-binding domain antibody test, which is widely available, with neutralizing test indicates that we can know indirectly the state of acquisition of functional immunity against wild and variant-type viruses in the clinical laboratory.

4.
J Infect Chemother ; 2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34774431

RESUMO

Genetic testing using reverse transcriptase real-time polymerase chain reaction (rRT-PCR) is the mainstay of diagnosis of COVID-19. However, it has not been fully investigated whether infectious viruses are contained in SARS-CoV-2 genome-positive specimens examined using the rRT-PCR test. In this study, we examined the correlation between the threshold Cycle (Ct) value obtained from the rRT-PCR test and virus isolation in cultured cells, using 533 consecutive clinical specimens of COVID-19 patients. The virus was isolated from specimens with a Ct value of less than 30 cycles, and the lower the Ct value, the more efficient the isolation rate. A cytopathic effect due to herpes simplex virus type 1 contamination was observed in one sample with a Ct value of 35 cycles. In a comparison of VeroE6/TMPRSS2 cells and VeroE6 cells used for virus isolation, VeroE6/TMPRSS2 cells isolated the virus 1.7 times more efficiently than VeroE6 cells. There was no significant difference between the two cells in the mean Ct value of the detectable sample. In conclusion, Lower Ct values in the PCR test were associated with higher virus isolation rates, and VeroE6/TMPRSS2 cells were able to isolate viruses more efficiently than VeroE6 cells.

5.
Sci Rep ; 11(1): 16535, 2021 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-34400739

RESUMO

Adaptive immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) dynamics remain largely unknown. The neutralizing antibody (NAb) levels in patients with coronavirus disease 2019 (COVID-19) are helpful for understanding the pathology. Using SARS-CoV-2 pseudotyped virus, serum sample neutralization values in symptomatic COVID-19 patients were measured using the chemiluminescence reduction neutralization test (CRNT). At least two sequential serum samples collected during hospitalization were analyzed to assess NAbs neutralizing activity dynamics at different time points. Of the 11 patients, four (36.4%), six (54.5%), and one (9.1%) had moderate, severe, and critical disease, respectively. Fifty percent neutralization (N50%-CRNT) was observed upon admission in 90.9% (10/11); all patients acquired neutralizing activity 2-12 days after onset. In patients with moderate disease, neutralization was observed at earliest within two days after symptom onset. In patients with severe-to-critical disease, neutralization activity increased, plateauing 9-16 days after onset. Neutralization activity on admission was significantly higher in patients with moderate disease than in patients with severe-to-critical disease (relative % of infectivity, 6.4% vs. 41.1%; P = .011). Neutralization activity on admission inversely correlated with disease severity. The rapid NAb response may play a crucial role in preventing the progression of COVID-19.


Assuntos
Imunidade Adaptativa , Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , COVID-19/diagnóstico , SARS-CoV-2/imunologia , Idoso , Idoso de 80 Anos ou mais , Anticorpos Antivirais/imunologia , COVID-19/sangue , COVID-19/imunologia , COVID-19/virologia , Teste de Ácido Nucleico para COVID-19 , Progressão da Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Testes de Neutralização/estatística & dados numéricos , Estudos Retrospectivos , SARS-CoV-2/genética , SARS-CoV-2/isolamento & purificação , Índice de Gravidade de Doença , Fatores de Tempo
6.
Viruses ; 13(6)2021 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-34205062

RESUMO

Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne bunyavirus that causes severe disease in humans with case fatality rates of approximately 30%. There are few treatment options for SFTSV infection. SFTSV RNA synthesis is conducted using a virus-encoded complex with RNA-dependent RNA polymerase activity that is required for viral propagation. This complex and its activities are, therefore, potential antiviral targets. A library of small molecule compounds was processed using a high-throughput screening (HTS) based on an SFTSV minigenome assay (MGA) in a 96-well microplate format to identify potential lead inhibitors of SFTSV RNA synthesis. The assay confirmed inhibitory activities of previously reported SFTSV inhibitors, favipiravir and ribavirin. A small-scale screening using MGA identified four candidate inhibitors that inhibited SFTSV minigenome activity by more than 80% while exhibiting less than 20% cell cytotoxicity with selectivity index (SI) values of more than 100. These included mycophenolate mofetil, methotrexate, clofarabine, and bleomycin. Overall, these data demonstrate that the SFTSV MGA is useful for anti-SFTSV drug development research.

7.
PLoS Pathog ; 17(2): e1008859, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33534867

RESUMO

Severe fever with thrombocytopenia syndrome (SFTS) caused by a species Dabie bandavirus (formerly SFTS virus [SFTSV]) is an emerging hemorrhagic infectious disease with a high case-fatality rate. One of the best strategies for preventing SFTS is to develop a vaccine, which is expected to induce both humoral and cellular immunity. We applied a highly attenuated but still immunogenic vaccinia virus strain LC16m8 (m8) as a recombinant vaccine for SFTS. Recombinant m8s expressing SFTSV nucleoprotein (m8-N), envelope glycoprotein precursor (m8-GPC), and both N and GPC (m8-N+GPC) in the infected cells were generated. Both m8-GPC- and m8-N+GPC-infected cells were confirmed to produce SFTSV-like-particles (VLP) in vitro, and the N was incorporated in the VLP produced by the infection of cells with m8-N+GPC. Specific antibodies to SFTSV were induced in mice inoculated with each of the recombinant m8s, and the mice were fully protected from lethal challenge with SFTSV at both 103 TCID50 and 105 TCID50. In mice that had been immunized with vaccinia virus strain Lister in advance of m8-based SFTSV vaccine inoculation, protective immunity against the SFTSV challenge was also conferred. The pathological analysis revealed that mice immunized with m8-GPC or m8-N+GPC did not show any histopathological changes without any viral antigen-positive cells, whereas the control mice showed focal necrosis with inflammatory infiltration with SFTSV antigen-positive cells in tissues after SFTSV challenge. The passive serum transfer experiments revealed that sera collected from mice inoculated with m8-GPC or m8-N+GPC but not with m8-N conferred protective immunity against lethal SFTSV challenge in naïve mice. On the other hand, the depletion of CD8-positive cells in vivo did not abrogate the protective immunity conferred by m8-based SFTSV vaccines. Based on these results, the recombinant m8-GPC and m8-N+GPC were considered promising vaccine candidates for SFTS.


Assuntos
Antígenos Virais/imunologia , Nucleoproteínas/imunologia , Phlebovirus/imunologia , Febre Grave com Síndrome de Trombocitopenia/prevenção & controle , Vacinas Atenuadas/administração & dosagem , Vacinas Sintéticas/administração & dosagem , Proteínas do Envelope Viral/imunologia , Animais , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Febre Grave com Síndrome de Trombocitopenia/imunologia , Febre Grave com Síndrome de Trombocitopenia/virologia
8.
Virology ; 556: 124-132, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33561699

RESUMO

The heartland virus (HRTV) is a novel phlebovirus that causes severe infections in the USA and closely related to the severe fever thrombocytopenia syndrome virus (SFTSV), a causative agent for SFTS in Asia. The entry mechanisms of HRTV remain unclear. Here, we developed the pseudotyped vesicular stomatitis virus bearing the HRTV glycoprotein (GP) (HRTVpv), and the antigenicity and the entry mechanisms of HRTV were analyzed. HRTVpv was neutralized by anti-SFTSV Gc antibody, but not the anti-SFTSV Gn antibodies. Entry of HRTVpv to cells was inhibited by bafilomycin A1 and dynasore, and but it was enhanced in cells overexpressed with C-type lectins. Production of infectious HRTVpv and SFTSVpv was reduced by Nn-DNJ, α-glucosidase inhibitor. The entry of HRTV occurs via pH- and dynamin-dependent endocytosis. Furthermore, Nn-DNJ may be a possible therapeutic agent against HRTV and SFTSV.

10.
Virol J ; 18(1): 16, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33435994

RESUMO

BACKGROUND: SARS-CoV-2 is a novel coronavirus that emerged in 2019 and is now classified in the genus Coronavirus with closely related SARS-CoV. SARS-CoV-2 is highly pathogenic in humans and is classified as a biosafety level (BSL)-3 pathogen, which makes manipulating it relatively difficult due to its infectious nature. METHODS: To circumvent the need for BSL-3 laboratories, an alternative assay was developed that avoids live virus and instead uses a recombinant VSV expressing luciferase and possesses the full length or truncated spike proteins of SARS-CoV-2. Furthermore, to measure SARS-CoV-2 neutralizing antibodies under BSL2 conditions, a chemiluminescence reduction neutralization test (CRNT) for SARS-CoV-2 was developed. The neutralization values of the serum samples collected from hospitalized patients with COVID-19 or SARS-CoV-2 PCR-negative donors against the pseudotyped virus infection evaluated by the CRNT were compared with antibody titers determined from an enzyme-linked immunosorbent assay (ELISA) or an immunofluorescence assay (IFA). RESULTS: The CRNT, which used whole blood collected from hospitalized patients with COVID-19, was also examined. As a result, the inhibition of pseudotyped virus infection was specifically observed in both serum and whole blood and was also correlated with the results of the IFA. CONCLUSIONS: In conclusion, the CRNT for COVID-19 is a convenient assay system that can be performed in a BSL-2 laboratory with high specificity and sensitivity for evaluating the occurrence of neutralizing antibodies against SARS-CoV-2.


Assuntos
Anticorpos Neutralizantes/sangue , Teste Sorológico para COVID-19/métodos , COVID-19/sangue , Testes de Neutralização/métodos , SARS-CoV-2/imunologia , Glicoproteína da Espícula de Coronavírus/imunologia , Vírus da Estomatite Vesicular Indiana/genética , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , COVID-19/imunologia , Linhagem Celular , Convalescença , Humanos , Concentração Inibidora 50 , Luminescência , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/genética
11.
Biomol Ther (Seoul) ; 29(3): 282-289, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33424013

RESUMO

A novel coronavirus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), caused a worldwide pandemic. Our aim in this study is to produce new fusion inhibitors against SARS-CoV-2, which can be the basis for developing new antiviral drugs. The fusion core comprising the heptad repeat domains (HR1 and HR2) of SARS-CoV-2 spike (S) were used to design the peptides. A total of twelve peptides were generated, comprising a short or truncated 24-mer (peptide #1), a long 36-mer peptide (peptide #2), and ten peptide #2 analogs. In contrast to SARS-CoV, SARS-CoV-2 S-mediated cell-cell fusion cannot be inhibited with a minimal length, 24-mer peptide. Peptide #2 demonstrated potent inhibition of SARS-CoV-2 S-mediated cell-cell fusion at 1 µM concentration. Three peptide #2 analogs showed IC50 values in the low micromolar range (4.7-9.8 µM). Peptide #2 inhibited the SARS-CoV-2 pseudovirus assay at IC50=1.49 µM. Given their potent inhibition of viral activity and safety and lack of cytotoxicity, these peptides provide an attractive avenue for the development of new prophylactic and therapeutic agents against SARS-CoV-2.

12.
PLoS One ; 15(12): e0243597, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33296437

RESUMO

OBJECTIVE: To investigate the relationship between viral load and secondary transmission in novel coronavirus disease 2019 (COVID-19). METHODS: Epidemiological and clinical data were obtained from immunocompetent laboratory-confirmed patients with COVID-19 who were admitted to and/or from whom viral loads were measured at Toyama University Hospital. Using a case-control approach, index patients who transmitted the disease to at least one other patient were analysed as "cases" (index patients) compared with patients who were not the cause of secondary transmission (non-index patients, analysed as "controls"). The viral load time courses were assessed between the index and non-index symptomatic patients using non-linear regression employing a standard one-phase decay model. RESULTS: In total, 28 patients were included in the analysis. Median viral load at the initial sample collection was significantly higher in symptomatic than in asymptomatic patients and in adults than in children. Among symptomatic patients (n = 18), non-linear regression models showed that the estimated viral load at onset was higher in the index than in the non-index patients (median [95% confidence interval]: 6.6 [5.2-8.2] vs. 3.1 [1.5-4.8] log copies/µL, respectively). In adult (symptomatic and asymptomatic) patients (n = 21), median viral load at the initial sample collection was significantly higher in the index than in the non-index patients (p = 0.015, 3.3 vs. 1.8 log copies/µL, respectively). CONCLUSIONS: High nasopharyngeal viral loads around onset may contribute to secondary transmission of COVID-19. Viral load may help provide a better understanding of why transmission is observed in some instances, but not in others, especially among household contacts.


Assuntos
COVID-19 , Modelos Biológicos , Nasofaringe , SARS-CoV-2/metabolismo , Carga Viral , Adolescente , Adulto , Idoso , COVID-19/metabolismo , COVID-19/transmissão , Estudos de Casos e Controles , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Nasofaringe/metabolismo , Nasofaringe/virologia
13.
J Infect Chemother ; 26(12): 1324-1327, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32900659

RESUMO

Most patients with coronavirus disease 2019 (COVID-19) have just only mild symptoms, but about 5% are very severe. Although extracorporeal membranous oxygenation (ECMO) is sometimes used in critically patients with COVID-19, ECMO is only an adjunct, not the main treatment. If the patient's condition deteriorates and it is determined to be irreversible, it is necessary to decide to stop ECMO. A 54-year-old man was admitted on day 6 of onset with a chief complaint of high fever and cough. Computed tomography (CT) showed a ground glass opacity in both lungs, and reverse transcription-polymerase chain reaction (RT-PCR) diagnosed COVID-19. He was admitted to the hospital and started to receive oxygen and favipiravir. After that, his respiratory condition deteriorated, and he was intubated and ventilated on day 9 of onset, and ECMO was introduced on day 12. Two days after the introduction of ECMO, C-reactive protein (CRP) increased, chest X-p showed no improvement in pneumonia, and PaO2/FiO2 decreased again. As D-dimer rose and found a blood clot in the ECMO circuit, we had to decide whether to replace the circuit and continue with ECMO or stop ECMO. At this time, the viral load by RT-PCR was drastically reduced to about 1/1750. We decided to continue ECMO therapy and replaced the circuit. The patient's respiratory status subsequently improved and ECMO was stopped on day 21 of onset. In conclusion, viral load measurement by RT-PCR may be one of the indicators for promoting the treatment of severe COVID-19 patients.


Assuntos
Betacoronavirus/isolamento & purificação , Infecções por Coronavirus/terapia , Infecções por Coronavirus/virologia , Oxigenação por Membrana Extracorpórea/métodos , Pneumonia Viral/terapia , Pneumonia Viral/virologia , Carga Viral/métodos , Amidas/uso terapêutico , Antivirais/uso terapêutico , COVID-19 , Teste para COVID-19 , Técnicas de Laboratório Clínico , Infecções por Coronavirus/diagnóstico , Tomada de Decisões , Hospitalização , Humanos , Pulmão/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Pandemias , Pneumonia Viral/diagnóstico , Pirazinas/uso terapêutico , Reação em Cadeia da Polimerase Via Transcriptase Reversa , SARS-CoV-2 , Tomografia Computadorizada por Raios X , Resultado do Tratamento
14.
Antiviral Res ; 182: 104926, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32882323

RESUMO

Severe fever with thrombocytopenia syndrome (SFTS), an emerging viral infectious disease with a high case fatality rate, is caused by the SFTS virus (SFTSV). Although several cellular molecules involved in viral entry have been identified, the entry mechanisms of SFTSV remain unclear. In this study, we screened the protein kinase inhibitors in inhibitory effects on the infection of Vero cells with SFTSV using InhibitorSelect™ Protein Kinase Library Series (Merck & Co., Inc., Kenilworth, NJ, USA). Several types of inhibitors targeted to platelet-derived growth factor receptor ß (PDGFRß) inhibited the infection of Vero, Huh7, and NIH3T3 cells with SFTSV in a dose-dependent manner within the noncytotoxic range. In addition, these protein kinase inhibitors also inhibited the infection of the target cells with SFTSV glycoprotein (SFTSV-GP) pseudotyped virus (SFTSVpv). Activation of PDGFRß phosphorylation was detected in SFTSV-treated cells. The infectivities of SFTSVpv were specifically decreased not only in NIH3T3 cells treated with siRNA for PDGFRß but also in NIH3T3 cells treated with anti-PDGFRß neutralizing antibody in a dose-dependent manner. SFTSV growth and entry of SFTSVpv were also inhibited by Akt inhibitors. Activation of Akt phosphorylation was also detected in SFTSV-treated cells. These data indicate that PDGFRß is one of the important host factors in the entry steps of SFTSV.


Assuntos
Phlebovirus/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Receptor beta de Fator de Crescimento Derivado de Plaquetas/metabolismo , Febre Grave com Síndrome de Trombocitopenia/virologia , Internalização do Vírus , Animais , Benzimidazóis/farmacologia , Benzotiazóis/farmacologia , Linhagem Celular , Chlorocebus aethiops , Interações entre Hospedeiro e Microrganismos , Humanos , Camundongos , Células NIH 3T3 , Proteína Oncogênica v-akt/metabolismo , Phlebovirus/crescimento & desenvolvimento , Fosforilação , Receptor beta de Fator de Crescimento Derivado de Plaquetas/antagonistas & inibidores , Células Vero
15.
Viruses ; 12(8)2020 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-32824338

RESUMO

Lymphocytic choriomeningitis virus (LCMV) is a prototypic arenavirus. The function of untranslated regions (UTRs) of the LCMV genome has not been well studied except for the extreme 19 nucleotide residues of both the 5' and 3' termini. There are internal UTRs composed of 58 and 41 nucleotide residues in the 5' and 3' UTRs, respectively, in the LCMV S segment. Their functional roles have yet to be elucidated. In this study, reverse genetics and minigenome systems were established for LCMV strain WE and the function of these regions were analyzed. It was revealed that nucleotides 20-40 and 20-38 located downstream of the 19 nucleotides in the 5' and 3' termini, respectively, were involved in viral genome replication and transcription. Furthermore, it was revealed that the other internal UTRs (nucleotides 41-77 and 39-60 in the 5' and 3' termini, respectively) in the S segment were involved in virulence in vivo, even though these regions did not affect viral growth capacity in Vero cells. The introduction of LCMV with mutations in these regions attenuates the virus and may enable the production of LCMV vaccine candidates.


Assuntos
Genoma Viral , Vírus da Coriomeningite Linfocítica/crescimento & desenvolvimento , Vírus da Coriomeningite Linfocítica/genética , Regiões não Traduzidas/fisiologia , Células A549 , Animais , Chlorocebus aethiops , Feminino , Humanos , Vírus da Coriomeningite Linfocítica/patogenicidade , Camundongos , Mutação , RNA Viral/química , Genética Reversa , Organismos Livres de Patógenos Específicos , Células Vero , Virulência , Replicação Viral
16.
Microbiol Immunol ; 64(1): 33-51, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31692019

RESUMO

The spike (S) protein of coronavirus, which binds to cellular receptors and mediates membrane fusion for cell entry, is a candidate vaccine target for blocking coronavirus infection. However, some animal studies have suggested that inadequate immunization against severe acute respiratory syndrome coronavirus (SARS-CoV) induces a lung eosinophilic immunopathology upon infection. The present study evaluated two kinds of vaccine adjuvants for use with recombinant S protein: gold nanoparticles (AuNPs), which are expected to function as both an antigen carrier and an adjuvant in immunization; and Toll-like receptor (TLR) agonists, which have previously been shown to be an effective adjuvant in an ultraviolet-inactivated SARS-CoV vaccine. All the mice immunized with more than 0.5 µg S protein without adjuvant escaped from SARS after infection with mouse-adapted SARS-CoV; however, eosinophilic infiltrations were observed in the lungs of almost all the immunized mice. The AuNP-adjuvanted protein induced a strong IgG response but failed to improve vaccine efficacy or to reduce eosinophilic infiltration because of highly allergic inflammatory responses. Whereas similar virus titers were observed in the control animals and the animals immunized with S protein with or without AuNPs, Type 1 interferon and pro-inflammatory responses were moderate in the mice treated with S protein with and without AuNPs. On the other hand, the TLR agonist-adjuvanted vaccine induced highly protective antibodies without eosinophilic infiltrations, as well as Th1/17 cytokine responses. The findings of this study will support the development of vaccines against severe pneumonia-associated coronaviruses.


Assuntos
Adjuvantes Imunológicos/farmacologia , Infecções por Coronavirus/prevenção & controle , Ouro/química , Imunoglobulina G/imunologia , Pulmão/imunologia , Nanopartículas Metálicas/química , Síndrome Respiratória Aguda Grave/prevenção & controle , Glicoproteína da Espícula de Coronavírus/imunologia , Análise de Variância , Animais , Anticorpos Antivirais/imunologia , Chlorocebus aethiops , Coronavirus/imunologia , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/virologia , Citocinas/metabolismo , Modelos Animais de Doenças , Feminino , Imunização , Pulmão/patologia , Camundongos , Camundongos Endogâmicos BALB C , Proteínas Recombinantes/imunologia , Vírus da SARS/imunologia , Síndrome Respiratória Aguda Grave/imunologia , Síndrome Respiratória Aguda Grave/virologia , Glicoproteína da Espícula de Coronavírus/genética , Receptores Toll-Like , Vacinação , Vacinas Sintéticas , Células Vero , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/imunologia , Vacinas Virais/imunologia , Vacinas Virais/farmacologia , Vacinas Virais/uso terapêutico
17.
Virology ; 535: 102-110, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31299486

RESUMO

Severe fever with thrombocytopenia syndrome (SFTS) is an infectious disease with a high fatality rate, caused by SFTS virus (SFTSV). Because little is known about the nature of SFTSV, basic studies are required for the developments of vaccines and effective therapies. In the present study, we identified the amino acid residue important for membrane fusion induced by the SFTSV glycoprotein (GP). Syncytium formations were observed in cells expressing the GPs of SFTSV Japanese strain (YG-1 and SPL030). In contrast, no or only weak syncytium formations were induced in cells expressing GP of SFTSV Chinese strain (HB29). The replacement of arginine at amino acid residue 962 with serine in HB29 GP (R962S) induced membrane fusion, while the replacement of serine at residue 962 with arginine in YG1 GP (S962R) did not. These data indicate that serine at residue 962 in the SFTSV-GP is critical for inducing membrane fusion and viral infection.


Assuntos
Phlebovirus/fisiologia , Proteínas Virais de Fusão/metabolismo , Internalização do Vírus , Substituição de Aminoácidos , Fusão Celular , Células Gigantes/citologia , Células Gigantes/virologia , Mutagênese Sítio-Dirigida , Phlebovirus/genética , Proteínas Virais de Fusão/genética
19.
PLoS One ; 13(10): e0206416, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30365543

RESUMO

Severe fever with thrombocytopenia syndrome (SFTS), caused by SFTS virus (SFTSV), is a viral hemorrhagic fever with a high case fatality rate. Favipiravir was reported to be effective in the treatment of SFTSV infection in vivo in type I interferon receptor knockout (IFNAR-/-) mice at treatment dosages of both 60 mg/kg/day and 300 mg/kg/day for a duration of 5 days. In this study, the efficacy of favipiravir at dosages of 120 mg/kg/day and 200 mg/kg/day against SFTSV infection in an IFNAR-/- mouse infection model was investigated. IFNAR-/- mice were subcutaneously infected with SFTSV at a 1.0 × 10(6) 50% tissue culture infectious dose followed by twice daily administration of favipiravir, comprising a total dose of either 120 mg/kg/day or 200 mg/kg/day. The treatment was initiated either immediately post infection or at predesignated time points post infection. Neutralizing antibodies in the convalescent-phase mouse sera was examined by the pseudotyped VSV system. All mice treated with favipiravir at dosages of 120 mg/kg/day or 200 mg/kg/day survived when the treatment was initiated at no later than 4 days post infection. A decrease in body weight of mice was observed when the treatment was initiated at 3-4 days post infection. Furthermore, all control mice died. The body weight of mice did not decrease when treatment with favipiravir was initiated immediately post infection at dosages of 120 mg/kg/day and 200 mg/kg/day. Neutralizing antibodies were detected in the convalescent-phase mouse sera. Similar to the literature-reported peritoneal administration of favipiravir at 300 mg/kg/day, the oral administration of favipiravir at dosages of 120 mg/kg/day and 200 mg/kg/day to IFNAR-/- mice infected with SFTSV was effective.


Assuntos
Amidas/administração & dosagem , Amidas/farmacologia , Febre por Flebótomos/tratamento farmacológico , Phlebovirus/fisiologia , Pirazinas/administração & dosagem , Pirazinas/farmacologia , Administração Oral , Amidas/uso terapêutico , Animais , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/imunologia , Chlorocebus aethiops , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Camundongos , Phlebovirus/efeitos dos fármacos , Phlebovirus/imunologia , Pirazinas/uso terapêutico , Células Vero
20.
J Infect Chemother ; 24(10): 802-806, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30017796

RESUMO

Severe fever with thrombocytopenia syndrome (SFTS) was first identified as an emerging tick-borne infectious disease caused by the SFTS virus (SFTSV) in China and has also been found to be endemic to Japan and South Korea, indicating that SFTS is of great concern in East Asia. The aim of the present study was to determine the seroprevalence of SFTSV antibodies in humans and animals in SFTS-endemic regions of Japan. One of 694 (0.14%) healthy persons over 50 years of age and 20 of 107 (18.7%) wild and domestic animals in Ehime prefecture of western Japan were determined to be seropositive for SFTSV antibodies by virus neutralization test and ELISA, respectively. The seropositive person, a healthy 74-year-old woman, was a resident of the southwest part of Ehime prefecture engaged in citriculture and field work. This woman's sample exhibited neutralizing activity against SFTSV although she had neither a clear experience with tick bites nor SFTS-like clinical illness. These findings indicate that most people living in the endemic regions are not infected with SFTSV and suggest that most of the SFTS patients reported so far do not reflect the tip of an iceberg of people infected with SFTSV, but at the same time, that SFTSV infection does not always induce severe SFTS-associated symptoms. These findings also suggested that SFTSV has been maintained in nature within animal species and ticks.


Assuntos
Anticorpos Antivirais/sangue , Infecções por Bunyaviridae/epidemiologia , Infecções por Bunyaviridae/imunologia , Doenças Endêmicas , Phlebovirus/imunologia , Idoso , Animais , Infecções por Bunyaviridae/sangue , Infecções por Bunyaviridae/prevenção & controle , China/epidemiologia , Feminino , Humanos , Japão/epidemiologia , Masculino , Pessoa de Meia-Idade , Testes de Neutralização , República da Coreia/epidemiologia , Fatores de Risco , Estudos Soroepidemiológicos , Doenças Transmitidas por Carrapatos/epidemiologia , Doenças Transmitidas por Carrapatos/imunologia , Doenças Transmitidas por Carrapatos/prevenção & controle
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