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1.
J Microbiol Methods ; 195: 106454, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35351489

RESUMEN

We developed a multiplex real-time PCR assay with amplicon melting curve analysis to rapidly discriminate Corynebacterium ulcerans from Corynebacterium pseudotuberculosis and detect the bacterial diphtheria toxin gene. This assay should be a valuable tool for identification of potentially toxigenic C. ulcerans.


Asunto(s)
Infecciones por Corynebacterium , Corynebacterium pseudotuberculosis , Difteria , Corynebacterium/genética , Infecciones por Corynebacterium/diagnóstico , Infecciones por Corynebacterium/microbiología , Corynebacterium pseudotuberculosis/genética , Difteria/microbiología , Toxina Diftérica/genética , Humanos , Reacción en Cadena en Tiempo Real de la Polimerasa
2.
Curr Microbiol ; 78(1): 265-273, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33095293

RESUMEN

This study investigated the genetic and pathogenic variation of the subgroups of clade 2 strains of Shiga toxin (Stx)-producing Escherichia coli (STEC) O157. A total of 111 strains of STEC O157 isolated in Shimane prefecture, Japan, were classified in clade 2 (n = 39), clade 3 (n = 16), clade 4/5 (n = 3), clade 7 (n = 14), clade 8 (n = 17), and clade 12 (n = 22) by single-nucleotide polymorphism analysis and lineage-specific polymorphism assay-6. These results showed a distinct difference from our previous study in which clade 3 strains were the most prevalent strains in three other prefectures in Japan, indicating that the clade distribution of O157 strains was different in different geographic areas in Japan. Phylogenetic analysis using insertion sequence (IS) 629 distribution data showed that clade 2 strains formed two clusters, designated 2a and 2b. Stx2 production by cluster 2b strains was significantly higher than by cluster 2a strains (P < 0.01). In addition, population genetic analysis of the clade 2 strains showed significant linkage disequilibrium in the IS629 distribution of the strains in clusters 2a and 2b (P < 0.05). The ΦPT values calculated using the IS629 distribution data indicated that strains in clusters 2a and 2b were genetically different (P < 0.001). Cluster 2b strains are a highly pathogenic phylogenetic group and their geographic spread may be a serious public health concern.


Asunto(s)
Infecciones por Escherichia coli , Escherichia coli O157 , Infecciones por Escherichia coli/epidemiología , Escherichia coli O157/genética , Humanos , Japón , Filogenia , Prevalencia , Toxinas Shiga
3.
Viruses ; 12(8)2020 08 16.
Artículo en Inglés | MEDLINE | ID: mdl-32824338

RESUMEN

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.


Asunto(s)
Genoma Viral , Virus de la Coriomeningitis Linfocítica/crecimiento & desarrollo , Virus de la Coriomeningitis Linfocítica/genética , Regiones no Traducidas/fisiología , Células A549 , Animales , Chlorocebus aethiops , Femenino , Humanos , Virus de la Coriomeningitis Linfocítica/patogenicidad , Ratones , Mutación , ARN Viral/química , Genética Inversa , Organismos Libres de Patógenos Específicos , Células Vero , Virulencia , Replicación Viral
4.
Clin Exp Nephrol ; 23(11): 1306-1314, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31428892

RESUMEN

BACKGROUND: Urinary tract infections caused by extended-spectrum beta-lactamase-producing bacteria are increasing worldwide. At our hospital, the number of pediatric patients hospitalized because of an upper urinary tract infection has dramatically increased since 2016. In total, 60.5% of urinary tract infections are caused by extended-spectrum beta-lactamase-producing Escherichia coli. Such a high prevalence of extended-spectrum beta-lactamase-producing E. coli has not been detected previously in Japan. Therefore, we evaluated the clinical and bacteriologic characteristics and efficacy of antibiotics against upper urinary tract infections caused by E. coli in children. METHODS: This retrospective study surveyed 152 patients who were hospitalized in the pediatric department of Shimane Prefectural Central Hospital because of upper urinary tract infections caused by E. coli. Medical records were reviewed to examine patient characteristics. O antigens, antibiotic susceptibility, gene typing, and pulse-field gel electrophoresis were studied at the Shimane Prefectural Institute of Public Health and Environmental Science. RESULTS: Urine sample analyses showed extended-spectrum beta-lactamase types such as CTX-M-9 and plural virulence genes. We changed the primary antibiotic treatment to flomoxef or cefmetazole to treat upper urinary tract infections caused by Gram-negative bacilli. After changing treatment, the time to fever alleviation was significantly shortened. CONCLUSION: Extended-spectrum beta-lactamase-producing E. coli should be suspected in community-acquired upper urinary tract infections. Therefore, when treating patients, it is necessary to focus on antibiotic susceptibility and the prevalence of extended-spectrum beta-lactamase-producing bacteria found in each area. Flomoxef and cefmetazole are useful primary treatments for upper urinary tract infections caused by extended-spectrum beta-lactamase-producing E. coli.


Asunto(s)
Antibacterianos/uso terapéutico , Cefmetazol/uso terapéutico , Cefalosporinas/uso terapéutico , Infecciones Comunitarias Adquiridas/tratamiento farmacológico , Infecciones por Escherichia coli/tratamiento farmacológico , Escherichia/enzimología , Infecciones Urinarias/tratamiento farmacológico , Adolescente , Niño , Preescolar , Infecciones Comunitarias Adquiridas/microbiología , Farmacorresistencia Bacteriana Múltiple/genética , Escherichia/genética , Infecciones por Escherichia coli/microbiología , Proteínas de Escherichia coli/biosíntesis , Proteínas de Escherichia coli/genética , Femenino , Genotipo , Humanos , Lactante , Recién Nacido , Masculino , Antígenos O/metabolismo , Estudios Retrospectivos , Infecciones Urinarias/microbiología , Virulencia/genética , beta-Lactamasas/biosíntesis , beta-Lactamasas/genética
6.
PLoS One ; 13(10): e0206416, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30365543

RESUMEN

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.


Asunto(s)
Amidas/administración & dosificación , Amidas/farmacología , Fiebre por Flebótomos/tratamiento farmacológico , Phlebovirus/fisiología , Pirazinas/administración & dosificación , Pirazinas/farmacología , Administración Oral , Amidas/uso terapéutico , Animales , Anticuerpos Neutralizantes/sangre , Anticuerpos Neutralizantes/inmunología , Chlorocebus aethiops , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Ratones , Phlebovirus/efectos de los fármacos , Phlebovirus/inmunología , Pirazinas/uso terapéutico , Células Vero
7.
J Infect Chemother ; 24(10): 802-806, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30017796

RESUMEN

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.


Asunto(s)
Anticuerpos Antivirales/sangre , Infecciones por Bunyaviridae/epidemiología , Infecciones por Bunyaviridae/inmunología , Enfermedades Endémicas , Phlebovirus/inmunología , Anciano , Animales , Infecciones por Bunyaviridae/sangre , Infecciones por Bunyaviridae/prevención & control , China/epidemiología , Femenino , Humanos , Japón/epidemiología , Masculino , Persona de Mediana Edad , Pruebas de Neutralización , República de Corea/epidemiología , Factores de Riesgo , Estudios Seroepidemiológicos , Enfermedades por Picaduras de Garrapatas/epidemiología , Enfermedades por Picaduras de Garrapatas/inmunología , Enfermedades por Picaduras de Garrapatas/prevención & control
8.
J Virol Methods ; 251: 22-29, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-28993122

RESUMEN

Since discovering the Middle East respiratory syndrome coronavirus (MERS-CoV) as a causative agent of severe respiratory illness in the Middle East in 2012, serological testing has been conducted to assess antibody responses in patients and to investigate the zoonotic reservoir of the virus. Although the virus neutralization test is the gold standard assay for MERS diagnosis and for investigating the zoonotic reservoir, it uses live virus and so must be performed in high containment laboratories. Competitive ELISA (cELISA), in which a labeled monoclonal antibody (MAb) competes with test serum antibodies for target epitopes, may be a suitable alternative because it detects antibodies in a species-independent manner. In this study, novel MAbs against the spike protein of MERS-CoV were produced and characterized. One of these MAbs was used to develop a cELISA. The cELISA detected MERS-CoV-specific antibodies in sera from MERS-CoV-infected rats and rabbits immunized with the spike protein of MERS-CoV. The MAb-based cELISA was validated using sera from Ethiopian dromedary camels. Relative to the neutralization test, the cELISA detected MERS-CoV-specific antibodies in 66 Ethiopian dromedary camels with a sensitivity and specificity of 98% and 100%, respectively. The cELISA and neutralization test results correlated well (Pearson's correlation coefficients=0.71-0.76, depending on the cELISA serum dilution). This cELISA may be useful for MERS epidemiological investigations on MERS-CoV infection.


Asunto(s)
Anticuerpos Monoclonales/sangre , Anticuerpos Monoclonales/inmunología , Anticuerpos Antivirales/inmunología , Ensayo de Inmunoadsorción Enzimática/métodos , Coronavirus del Síndrome Respiratorio de Oriente Medio/inmunología , Glicoproteína de la Espiga del Coronavirus/inmunología , Animales , Anticuerpos Monoclonales/aislamiento & purificación , Anticuerpos Antivirales/aislamiento & purificación , Camelus , Conejos , Ratas , Sensibilidad y Especificidad
9.
Arch Virol ; 162(6): 1529-1539, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28190201

RESUMEN

Pteropine orthoreovirus (PRV) causes respiratory tract illness (RTI) in humans. PRVs were isolated from throat swabs collected from 9 of 91 wild bats captured on the Mindanao Islands, The Philippines, in 2013. The nucleic acid sequence of the whole genome of each of these isolates was determined. Phylogenetic analysis based on predicted amino acid sequences indicated that the isolated PRVs were novel strains in which re-assortment events had occurred in the viral genome. Serum specimens collected from 76 of 84 bats were positive for PRV-neutralizing antibodies suggesting a high prevalence of PRV in wild bats in the Philippines. The bat-borne PRVs isolated in the Philippines were characterized in comparison to an Indonesian PRV isolate, Miyazaki-Bali/2007 strain, recovered from a human patient, revealing that the Philippine bat-borne PRVs had similar characteristics in terms of antigenicity to those of the Miyazaki-Bali/2007 strain, but with a slight difference (e.g., growth capacity in vitro). The impact of the Philippine bat-borne PRVs should be studied in human RTI cases in the Philippines.


Asunto(s)
Quirópteros/virología , Orthoreovirus/clasificación , Orthoreovirus/aislamiento & purificación , Infecciones por Reoviridae/veterinaria , Animales , Animales Salvajes/virología , Anticuerpos Neutralizantes/sangre , Quirópteros/inmunología , Genoma Viral , Humanos , Indonesia/epidemiología , Orthoreovirus/genética , Orthoreovirus/inmunología , Filipinas/epidemiología , ARN Viral/genética , Infecciones por Reoviridae/epidemiología , Infecciones por Reoviridae/virología
10.
J Infect Chemother ; 23(1): 45-50, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-28122687

RESUMEN

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne infectious disease caused by the SFTS virus (SFTSV). The aim of this study was to clarify whether SFTS is potentially mis-diagnosed as rickettsioses, including spotted fever, typhus fever, and scrub typhus, which are also tick-borne disease. A total of 464 serum samples collected from 222 patients with clinically suspected rickettsiosis between 1999 and 2012 were tested for antibodies against the SFTSV. Of the 464 serum samples, one was positive for antibodies against the virus in an enzyme-linked immunosorbent assay and indirect immunofluorescence assay. The patient of SFTSV antibody-positive sample (15 days after disease onset) was positive for SFTSV genome in the acute phase sample (3 days after disease onset) as determined via reverse transcription-quantitative polymerase chain reaction. This patient, who was a resident of the Yamaguchi prefecture in Western Japan, was in his 40s when he showed symptoms in 2011. As the result, 1 of 222 patients, who was clinically suspected of rickettsiosis, was retrospectively diagnosed with SFTS. In this case, both the C-reactive protein and white blood cell count levels were lower than the ranges of these parameters for patients diagnosed with rickettsiosis. Therefore, SFTS should be considered in the differential diagnosis for rickettsiosis in Japan.


Asunto(s)
Fiebre/diagnóstico , Fiebre/virología , Trombocitopenia/diagnóstico , Trombocitopenia/virología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Recuento de Células Sanguíneas/métodos , Proteína C-Reactiva/metabolismo , Niño , Preescolar , Femenino , Fiebre/metabolismo , Humanos , Lactante , Recién Nacido , Japón , Masculino , Persona de Mediana Edad , Phlebovirus , Estudios Retrospectivos , Infecciones por Rickettsia/diagnóstico , Infecciones por Rickettsia/metabolismo , Infecciones por Rickettsia/virología , Encuestas y Cuestionarios , Trombocitopenia/metabolismo , Enfermedades por Picaduras de Garrapatas/diagnóstico , Enfermedades por Picaduras de Garrapatas/metabolismo , Enfermedades por Picaduras de Garrapatas/virología , Adulto Joven
11.
J Virol Methods ; 244: 4-10, 2017 06.
Artículo en Inglés | MEDLINE | ID: mdl-28082164

RESUMEN

Severe fever with thrombocytopenia syndrome (SFTS) is a recently-discovered, potentially fatal infectious disease caused by SFTS virus (SFTSV). Due to the inability of SFTSV to make clear cytopathic effects (CPE) in cell culture, titration and neutralization assays of the virus require immunostaining of inoculated cells; consequently, the assays are time-consuming and expensive. In this report, we demonstrate the use of a highly-passaged SFTSV strain, p50-2, in a neutralization assay, which made clear plaques in inoculated Vero cells under neutral red staining. Furthermore, we performed molecular analyses to determine the characteristics of the strain. The results suggested that a single amino acid mutation within the viral glycoprotein conferred the ability to make clear plaques to SFTSV.


Asunto(s)
Pruebas de Neutralización/métodos , Phlebovirus/crecimiento & desarrollo , Phlebovirus/inmunología , Ensayo de Placa Viral/métodos , Sustitución de Aminoácidos , Animales , Chlorocebus aethiops , Mutación Missense , Pase Seriado , Células Vero , Proteínas Estructurales Virales/genética
12.
Am J Trop Med Hyg ; 95(6): 1351-1357, 2016 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-27928083

RESUMEN

Severe fever with thrombocytopenia syndrome (SFTS) is tick-borne viral disease that was first suspected in China in 2009. The causative virus (SFTSV) was isolated in 2009 and reported in 2011, and SFTSV expanded its geographic distribution in 2012-2013, from China to South Korea and Japan. Most SFTSV infections occur through Haemaphysalis longicornis However, SFTSV infection can also occur between family members, and nosocomial transmission of SFTSV is also possible through close contact with a patient. In this study, we first analyzed clinical, epidemiological, and laboratory data for SFTS patients and family members of an index patient in Korea. The S segment of SFTSV was amplified from the sera of three patients, and the S segment of SFTSV and IgG specific to SFTSV were detected in the serum from one family member; although this individual had no history of exposure to H. longicornis, she frequently had close contact with the index patient. In Korea, SFTSV infection among family members does not have to be reported, and we suggest that person-to-person transmission of SFTSV among family members is possible in Korea.


Asunto(s)
Infecciones por Bunyaviridae/virología , Phlebovirus/genética , Infecciones por Bunyaviridae/epidemiología , Análisis por Conglomerados , Familia , Resultado Fatal , Humanos , Inmunoglobulina G , Masculino , Filogenia , República de Corea/epidemiología
13.
mSphere ; 1(1)2016.
Artículo en Inglés | MEDLINE | ID: mdl-27303697

RESUMEN

Severe fever with thrombocytopenia syndrome virus (SFTSV) is the causative agent of SFTS, an emerging hemorrhagic fever. This disease has a high case fatality rate and is endemic to China, South Korea, and Japan. Because there are currently no effective therapeutics for SFTS, potent and safe antivirals are needed for the treatment of SFTS. The inhibitory effect of T-705 (favipiravir) on the replication of SFTSV in Vero cells was evaluated. Mice lacking the type I interferon receptor (IFNAR(-/-)) were used as an in vivo lethal model for SFTSV infection. T-705, which has been licensed as an anti-influenza drug in Japan, inhibits SFTSV replication both in vitro and in vivo. T-705 inhibited replication of SFTSV in Vero cells by 5 log units, with a 50% inhibitory concentration (IC50) and IC90 of 6.0 µM and 22 µM, respectively. Intraperitoneal or oral administration of T-705 for 5 days to IFNAR(-/-) mice infected with lethal SFTSV significantly improved survival rates (100% survival) without causing body weight loss and reduced the viral load in the serum. Ribavirin also inhibited SFTSV replication. However, it was less effective than T-705 both in vitro and in vivo. A time-of-drug-addition study revealed that therapeutic T-705 treatment of SFTSV infection in IFNAR(-/-) mice was effective. These results suggest that T-705 is a promising candidate for the treatment of SFTS. IMPORTANCE Severe fever with thrombocytopenia syndrome (SFTS), caused by SFTS virus (SFTSV), is a recently identified emerging viral infectious disease. Despite the medical importance of this disease, there are currently neither vaccines nor effective therapeutics for SFTS. T-705, which is a pyrazine derivative, has shown broad antiviral activity against various RNA viruses. The present study demonstrated, for the first time to our knowledge, the efficacy of T-705 in treating SFTSV infection in a mouse lethal model. T-705 showed a high efficacy in the treatment of SFTSV infection in the mouse model, even when treatments were initiated after onset of the disease.

14.
Emerg Microbes Infect ; 5: e44, 2016 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-27165561

RESUMEN

Pteropine orthoreovirus (PRV), potentially of bat origin, is reported to be a causative agent of emerging respiratory tract infections among humans in Southeast Asia. We evaluated the efficacy of serologic assays using the major outer capsid and cell attachment proteins (CAP) of PRV strains in the screening, confirmation and identification of three groups of human PRV infections; Indonesian/Japanese, Indonesian/Hong Kong and Malaysian strains. The different serologic assays were tested using rabbit polyclonal antisera raised against these proteins of selected PRV strains, and validation was carried out using sera from a Miyazaki-Bali/2007 PRV-infected patient and the patient's contacts. The results of this study showed that rabbit polyclonal antisera raised against the CAP of the Miyazaki-Bali/2007 PRV strain showed the highest reactivity to the Miyazaki-Bali/2007 PRV and to a lesser extent, cross-reactivity with the HK23629/07 and Melaka PRVs, respectively. Neutralization activity against the Miyazaki-Bali/2007 PRV was observed using rabbit anti-Miyazaki-Bali/2007 PRV CAP (320) but not with rabbit anti-HK23629/07 (<20) and Melaka (<20) PRV CAP. This lack of cross-neutralization, suggests the potential for human reinfection with different strains. The use of sera collected from contacts of the Miyazaki-Bali/2007 PRV-infected patient suggested that human-to-human infections with PRV are unlikely. Previously reported cases of PRV infections among human have been mild. However, the expanding geographic distribution of these viruses, of which its virulence remains unknown, warrants close monitoring to enable the development of prevention and control strategies in the event that a change in virulence occurs.


Asunto(s)
Enfermedades Transmisibles Emergentes/diagnóstico , Orthoreovirus/clasificación , Infecciones por Reoviridae/diagnóstico , Infecciones por Reoviridae/prevención & control , Pruebas Serológicas/métodos , Animales , Anticuerpos Antivirales/sangre , Enfermedades Transmisibles Emergentes/inmunología , Enfermedades Transmisibles Emergentes/prevención & control , Enfermedades Transmisibles Emergentes/virología , Ensayo de Inmunoadsorción Enzimática , Genoma Viral , Hong Kong/epidemiología , Humanos , Indonesia/epidemiología , Pruebas de Neutralización/métodos , Orthoreovirus/inmunología , Orthoreovirus/aislamiento & purificación , Filogenia , ARN Viral , Conejos , Infecciones por Reoviridae/virología , Infecciones del Sistema Respiratorio/diagnóstico , Infecciones del Sistema Respiratorio/epidemiología , Infecciones del Sistema Respiratorio/prevención & control , Infecciones del Sistema Respiratorio/virología , Análisis de Secuencia de ADN , Proteínas Virales/inmunología
15.
PLoS Negl Trop Dis ; 10(4): e0004595, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-27045364

RESUMEN

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne infectious disease with a high case fatality rate, and is caused by the SFTS virus (SFTSV). SFTS is endemic to China, South Korea, and Japan. The viral RNA level in sera of patients with SFTS is known to be strongly associated with outcomes. Virological SFTS diagnosis with high sensitivity and specificity are required in disease endemic areas. METHODOLOGY/PRINCIPAL FINDINGS: We generated novel monoclonal antibodies (MAbs) against the SFTSV nucleocapsid (N) protein and developed a sandwich antigen (Ag)-capture enzyme-linked immunosorbent assay (ELISA) for the detection of N protein of SFTSV using MAb and polyclonal antibody as capture and detection antibodies, respectively. The Ag-capture system was capable of detecting at least 350-1220 TCID50/100 µl/well from the culture supernatants of various SFTSV strains. The efficacy of the Ag-capture ELISA in SFTS diagnosis was evaluated using serum samples collected from patients suspected of having SFTS in Japan. All 24 serum samples (100%) containing high copy numbers of viral RNA (>105 copies/ml) showed a positive reaction in the Ag-capture ELISA, whereas 12 out of 15 serum samples (80%) containing low copy numbers of viral RNA (<105 copies/ml) showed a negative reaction in the Ag-capture ELISA. Among these Ag-capture ELISA-negative 12 samples, 9 (75%) were positive for IgG antibodies against SFTSV. CONCLUSIONS: The newly developed Ag-capture ELISA is useful for SFTS diagnosis in acute phase patients with high levels of viremia.


Asunto(s)
Anticuerpos Monoclonales/inmunología , Anticuerpos Antivirales/inmunología , Antígenos Virales/sangre , Infecciones por Bunyaviridae/diagnóstico , Proteínas de la Nucleocápside/sangre , Phlebovirus/aislamiento & purificación , Pruebas Serológicas/métodos , Pruebas Diagnósticas de Rutina/métodos , Ensayo de Inmunoadsorción Enzimática/métodos , Humanos , Sensibilidad y Especificidad
16.
J Virol ; 90(11): 5292-5301, 2016 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-26984731

RESUMEN

UNLABELLED: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging hemorrhagic fever with a high case fatality rate caused by SFTS virus (SFTSV). Effective vaccines and specific therapies for SFTS are urgently sought, and investigation into virus-host cell interactions is expected to contribute to the development of antiviral strategies. In this study, we have developed a pseudotype vesicular stomatitis virus (VSV) bearing the unmodified Gn/Gc glycoproteins (GPs) of SFTSV (SFTSVpv). We have analyzed the host cell entry of this pseudotype virus and native SFTSV. Both SFTSVpv and SFTSV exhibited high infectivity in various mammalian cell lines. The use of lysosomotropic agents indicated that virus entry occurred via pH-dependent endocytosis. SFTSVpv and SFTSV infectivity was neutralized by serial dilutions of convalescent-phase patient sera. Entry of SFTSVpv and growth of SFTSV were increased in Raji cells expressing not only the C-type lectin dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) but also DC-SIGN-related (DC-SIGNR) and liver and lymph node sinusoidal endothelial cell C-type lectin (LSECtin). 25-Hydroxycholesterol (25HC), a soluble oxysterol metabolite, inhibited the cell entry of SFTSVpv and the membrane fusion of SFTSV. These results indicate that pH-dependent endocytosis of SFTSVpv and SFTSV is enhanced by attachment to certain C-type lectins. SFTSVpv is an appropriate model for the investigation of SFTSV-GP-mediated cell entry and virus neutralization at lower biosafety levels. Furthermore, 25HC may represent a potential antiviral agent against SFTS. IMPORTANCE: SFTSV is a recently discovered bunyavirus associated with SFTS, a viral hemorrhagic fever with a high case fatality rate endemic to China, South Korea, and Japan. Because little is known about the characteristics of the envelope protein and entry mechanisms of SFTSV, further studies will be required for the development of a vaccine or effective therapies. In this study, we investigated the mechanism of SFTSV cell entry using SFTSVpv and the native virus. SFTSV can grow in nonsusceptible cell lines in the presence of certain C-type lectins. Moreover, 25HC, an oxysterol metabolite, may represent a potential therapeutic inhibitor of SFTSV infection.


Asunto(s)
Glicoproteínas/metabolismo , Phlebovirus/fisiología , Trombocitopenia/virología , Virus de la Estomatitis Vesicular Indiana/genética , Virus de la Estomatitis Vesicular Indiana/fisiología , Proteínas del Envoltorio Viral/metabolismo , Internalización del Virus , Animales , Moléculas de Adhesión Celular/metabolismo , Línea Celular , China , Endocitosis , Glicoproteínas/química , Humanos , Concentración de Iones de Hidrógeno , Hidroxicolesteroles/farmacología , Lectinas Tipo C/metabolismo , Pruebas de Neutralización , Fiebre por Flebótomos/virología , Phlebovirus/química , Receptores de Superficie Celular/metabolismo , Virus de la Estomatitis Vesicular Indiana/efectos de los fármacos , Virus de la Estomatitis Vesicular Indiana/crecimiento & desarrollo
17.
Jpn J Infect Dis ; 69(6): 510-516, 2016 Nov 22.
Artículo en Inglés | MEDLINE | ID: mdl-27000459

RESUMEN

The present study examined the susceptibility of rats to the Middle East respiratory syndrome coronavirus (MERS-CoV) and determined whether this animal is a suitable model for MERS-CoV infection. Immunohistochemical analysis identified dipeptidyl peptidase 4 (DPP4), a known receptor for MERS-CoV on type I pneumocytes from infected rats. Whereas adult rats developed antibodies against MERS-CoV spike protein after intranasal inoculation, there was no evidence of viral replication in the lungs of adult, young, or neonatal rats after intranasal inoculation with MERS-CoV. In addition, human DPP4-expressing rat kidney fibroblasts, but not rat DPP4-expressing cells, were susceptible to MERS-CoV. Taken together, these results suggest that the rat is not a useful animal model for studying MERS-CoV infection.


Asunto(s)
Resistencia a la Enfermedad , Coronavirus del Síndrome Respiratorio de Oriente Medio/crecimiento & desarrollo , Administración Intranasal , Animales , Línea Celular , Femenino , Especificidad del Huésped , Humanos , Inmunohistoquímica , Pulmón/virología , Embarazo , Ratas Endogámicas F344 , Ratas Endogámicas Lew , Tropismo Viral
18.
Jpn J Infect Dis ; 69(6): 525-527, 2016 Nov 22.
Artículo en Inglés | MEDLINE | ID: mdl-26743149

RESUMEN

Severe fever with thrombocytopenia syndrome (SFTS) is a novel bunyavirus infection caused by the SFTS virus (SFTSV, family Bunyaviridae, genus Phlebovirus) with a high case fatality rate. A previously healthy 72-year-old man showed symptoms of fever, general fatigue, and altered consciousness. He was hospitalized for treatment. On day 3, considering the day on which fever appeared first during the disease course as day 0, he had bloody emesis. An emergency upper gastrointestinal endoscopic examination revealed multiple ulcerative lesions with continuously oozing hemorrhage in the stomach. He died on day 7. He was retrospectively diagnosed as having SFTS, Although it was less likely that the gastric ulcerative lesions were directly induced by SFTSV replication, it was evident that hemorrhagic emesis might occur in the patient in association with the pathophysiology of SFTS. The real-time imaging of gastric ulcerative lesions in a patient with SFTS is reported.


Asunto(s)
Infecciones por Bunyaviridae/diagnóstico , Infecciones por Bunyaviridae/patología , Endoscopía del Sistema Digestivo , Phlebovirus/aislamiento & purificación , Anciano , Resultado Fatal , Humanos , Masculino , Úlcera Gástrica/etiología , Úlcera Gástrica/patología , Vómitos/etiología , Vómitos/patología
19.
Virol J ; 12: 181, 2015 Nov 02.
Artículo en Inglés | MEDLINE | ID: mdl-26527529

RESUMEN

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an acute infectious disease caused by SFTS virus and characterized by a high case fatality rate. Currently, there is no effective therapy for the disease. While the administration of ribavirin does not improve the case fatality rate or viral load in patient blood, it can inhibit viral infection in vitro. METHODS: Vero cells were pre-treated with interferons (IFNs) α, ß, and γ alone and in combination with ribavirin drugs and inoculated with SFTS virus. Three days later, supernatants were harvested and subjected to virus titration. An unpaired t-test was used for statistical analysis of the drugs' effects. RESULTS: While the effects of IFNγ at high concentrations were slightly weaker than those of the other IFNs, all IFNs showed dose-dependent inhibitory effects. The combined usage of IFNs with ribavirin at 90 % effective concentrations showed large inhibitory effects, with over a 3 log10 reduction in viral titers. CONCLUSIONS: The combined usage of one of type-I/II IFNs with ribavirin drastically reduced SFTS virus infection and therefore may be useful in the treatment of SFTS.


Asunto(s)
Antivirales/farmacología , Interacciones Farmacológicas , Interferones/farmacología , Phlebovirus/efectos de los fármacos , Ribavirina/farmacología , Animales , Chlorocebus aethiops , Pruebas de Sensibilidad Microbiana , Células Vero , Carga Viral
20.
Sci Rep ; 5: 16517, 2015 Nov 12.
Artículo en Inglés | MEDLINE | ID: mdl-26558341

RESUMEN

The emergence of orthoreoviruses as the causative agent of human respiratory illness over the past few years has led to a demand to determine their viral genome sequences. The whole genome sequencing of such RNA viruses using traditional methods, such as Sanger dideoxy sequencing following rapid amplification of cDNA ends presents a laborious challenge due to the numerous preparatory steps required before sequencing can commence. We developed a practical, time-efficient novel combination method capable of reducing the total time required from months to less than a week in the determination of whole genome sequence of Pteropine orthoreoviruses (PRV); through a combination of viral RNA purification and enrichment, adaptor ligation, reverse transcription, cDNA circularization and amplification, and next generation sequencing. We propose to call the method "modified rolling circular amplification with adaptor ligation - next generation sequencing (mRCA-NGS)". Here, we describe the technological focus and advantage of mRCA-NGS and its expansive application, exemplified through the phylogenetic understanding of the Miyazaki-Bali/2007 PRV.


Asunto(s)
Genoma Viral , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Orthoreovirus/genética , Animales , Línea Celular , Humanos , Orthoreovirus/clasificación , Orthoreovirus/aislamiento & purificación , Filogenia , ARN Viral/genética , Análisis de Secuencia de ADN/métodos
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