RESUMO
The unprecedented coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a serious threat to global public health. Development of effective therapies against SARS-CoV-2 is urgently needed. Here, we evaluated the antiviral activity of a remdesivir parent nucleotide analog, GS441524, which targets the coronavirus RNA-dependent RNA polymerase enzyme, and a feline coronavirus prodrug, GC376, which targets its main protease, using a mouse-adapted SARS-CoV-2 infected mouse model. Our results showed that GS441524 effectively blocked the proliferation of SARS-CoV-2 in the mouse upper and lower respiratory tracts via combined intranasal (i.n.) and intramuscular (i.m.) treatment. However, the ability of high-dose GC376 (i.m. or i.n. and i.m.) was weaker than GS441524. Notably, low-dose combined application of GS441524 with GC376 could effectively protect mice against SARS-CoV-2 infection via i.n. or i.n. and i.m. treatment. Moreover, we found that the pharmacokinetic properties of GS441524 is better than GC376, and combined application of GC376 and GS441524 had a synergistic effect. Our findings support the further evaluation of the combined application of GC376 and GS441524 in future clinical studies. ImportanceSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), which has seriously threatened global public health and economic development. Currently, effective therapies to treat COVID-19 are urgently needed. In this study, we assessed the efficacy of the preclinical inhibitors GC376 and GS441524 using a mouse-adapted SARS-CoV-2 infected mouse model for the first time. Our results showed that low-dose combined application of GC376 and GS441524 could effectively protect mice from HRB26M infection in the upper and lower respiratory tracts. Hence, the combined application should be developed and considered for future clinic practice.
RESUMO
Rabies remains an important worldwide health problem. Newcastle disease virus (NDV) was developed as a vaccine vector in animals by using a reverse genetics approach. Previously, our group generated a recombinant NDV (LaSota strain) expressing the complete rabies virus G protein (RVG), named rL-RVG. In this study, we constructed the variant rL-RVGTM, which expresses a chimeric rabies virus G protein (RVGTM) containing the ectodomain of RVG and the transmembrane domain (TM) and a cytoplasmic tail (CT) from the NDV fusion glycoprotein to study the function of RVG's TM and CT. The RVGTM did not detectably incorporate into NDV virions, though it was abundantly expressed at the surface of infected BHK-21 cells. Both rL-RVG and rL-RVGTM induced similar levels of NDV virus-neutralizing antibody (VNA) after initial and secondary vaccination in mice, whereas rabies VNA induction by rL-RVGTM was markedly lower than that induced by rL-RVG. Though rL-RVG could spread from cell to cell like that in rabies virus, rL-RVGTM lost this ability and spread in a manner similar to the parental NDV. Our data suggest that the TM and CT of RVG are essential for its incorporation into NDV virions and for spreading of the recombinant virus from the initially infected cells to surrounding cells.
Assuntos
Animais , Humanos , Camundongos , Formação de Anticorpos , Citoplasma , Glicoproteínas , Proteínas de Ligação ao GTP , Vírus da Doença de Newcastle , Doença de Newcastle , Pais , Vírus da Raiva , Raiva , Genética Reversa , Cauda , Vacinação , VírionRESUMO
Objective To discuss a real-time fluorescence quantitative polymerase chain reaction (FQ-PCR) wether if can be used to detect Brucella. Methods According to the BCSP31 gene sequences specific for Brucella, one pair of primers and one TaqMan probe were designed. A real-time PCR was developed with the BCSP31 fragments cloned into PMD18-T vector. The standard cure was established and the sensitivity, the species specificity and the stability of the assay were evaluated. The clinical blood specimens were detected by QT-PCR and compared with clinical diagnosis. Results The standard curve was established with the standard template and the relationship between the Ct and the DNA copy number was linear(r=0.999). The sensitivity of the real-time PCR was 5 copies/μl. The sensitivity of the common PCR was 5×102 copies/μl. The sensitivity was about 100 times higher than common PCR. Species specificity of this FQ-PCR assay evaluated using genomic DNA from 6 Bmcella strains and 5 non-Brucella strains and strong fluorescence was detected in all Brucella strains. The CV of intra-assay and inter-assay reproducibility were 0.71%,7.23%, reprectively. Twenty-four specimens from clinical brucellosis cases, 19 showed positive, the positive coincident rate was 79%(19/24). The negative results were obtained for all 31 negative control, and the negative coincident rate was 100%(31/31). Two were positive from all 30 specimens clinically suspected. Conclusions Highly specific, sensitive, repeatable and coincidental with clinic, this FQ-PCR is quite useful for rapid detection of tiny DNA of Brucella in various samples and laboratory diagnosis.
RESUMO
The two mammalian codon optimized genes, F and G genes of Nipah virus, were generated by assembly PCR, and inserted into mammalian expression vector pCAGGS under chicken beta-actin promoter to construct pCAGG-NiV-F and pCAGG-NiV-G. Syncytium formation was induced in BHK cells by plasmid pCAGG-NiV-F and pCAGG-NiV-G transfection, which indicate recombination proteins F and G were expressed in BHK cell and possessed good biologic activity. Six-week-old female BALB/c mice were intramuscularly primed with 100 microg pCAGG-NiV-F, pCAGG-NiV-G or pCAGG-NiV-F+ pCAGG-NiV-G respectively, and boosted with same dose after 4 weeks. The sera were collected at 3 weeks post second boost. The serum IgG against Nipah virus F and G proteins was detected by indirect ELISA using recombinant Baculovirus expressed Nipah F and G glycoproteins. The results showed that specific antibodies possessed good sensitivity and specificity. Furthermore, the G and F proteins' specific antibodies could neutralize the infectivity of VSVdeltaG* F/G (the NiV F and G envelope glycoproteins psudotyped recombinant vesicular stomatitis virus expressing green fluorescence protein). And, pCAGG-NiV-G also induced higher titer of neutralizing antibody response than pCAGG-NiV-F did. The result indicates that DAN immunization is an efficient vaccine strategy against Nipah virus.
Assuntos
Animais , Feminino , Camundongos , Anticorpos Antivirais , Sangue , Western Blotting , Ensaio de Imunoadsorção Enzimática , Camundongos Endogâmicos BALB C , Vírus Nipah , Alergia e Imunologia , Vacinas de DNA , Alergia e Imunologia , Proteínas do Envelope Viral , Genética , Alergia e Imunologia , Vacinas Virais , Alergia e ImunologiaRESUMO
The full-length porcine interferon gamma(PoIFN-gamma) cDNA, including the secretion signal peptide coding region was recloned into honor plasmid pFastBac 1 of Bac-To-Bac Baculovirus Expression System. These recombinant plasmids, pFastBac -PoIFN-gamma, were transformed into DH(10Bac) host bacteria to get recombinant shuttle plasmids, rBacmid-PoIFN-gamma. Recombinant baculovirus, rBac-PoIFN-gamma, was generated for expressing PoIFN-gamma, by transfecting rBacmid-PoIFN-gamma with Cellfectin Reagent into sf9 insect cells. The expression of PoIFN-gamma in insect cells was confirmed by Western Blot, indirect immunofluorescence assay and indirect ELISA. The antiviral activity assay shows that PoIFN-gamma expressed by the rBac-PoIFN-gamma can efficiently inhibit the replication of the recombinant Vesicular Stomatitis Virus expressing green fluorescence protein in PK-15 cells. The antiviral activity of PoIFN-gamma can be specifically blocked by anti-PoIFN-gamma mouse serum. The antiviral titer of culture supernatant of insect cells infected by rBac-PoIFN-gamma is 2 x 10(4) IU/mL. The results demonstrat that the rBac-PoIFN-gamma can express rPoIFN-gamma efficiently and rPoIFN-gamma has high antiviral activity.
Assuntos
Animais , Camundongos , Antivirais , Metabolismo , Farmacologia , Baculoviridae , Genética , Western Blotting , Linhagem Celular , Ensaio de Imunoadsorção Enzimática , Técnica Indireta de Fluorescência para Anticorpo , Expressão Gênica , Proteínas de Fluorescência Verde , Genética , Metabolismo , Soros Imunes , Alergia e Imunologia , Interferon gama , Genética , Alergia e Imunologia , Metabolismo , Farmacologia , Camundongos Endogâmicos BALB C , Microscopia de Fluorescência , Proteínas Recombinantes , Spodoptera , Suínos , Vesiculovirus , Genética , Replicação ViralRESUMO
A recombinant vaccinia virus (rWR-SARS-S)expressing spike protein of severe acute respiratory syndrome coronavirus was constructed. The expression of full length recombinant SARS spike protein (rSS) in HeLa cells possessing specific reaction ability to chicken anti-sera was confirmed by SDS-PAGE and Western-blot (190 kD). HeLa cells infected with rWR-SARS-S also showed high sensitivity in detecting specific serum antibody by indirect immunofluoresence assay (IFA). The results above indicated that the availability of such a faithful model system offers particular advantages for the study of SARS in that it reduces the need for direct manipulation of an exotic pathogen. In the absence of infectious SARS, we may safely carry out detailed biochemical and genetic manipulations to investigate features of viral replication and gene function, as well as explore new avenue for vaccine development.
Assuntos
Animais , Humanos , Camundongos , Anticorpos Antivirais , Alergia e Imunologia , Antígenos Virais , Alergia e Imunologia , Western Blotting , Galinhas , Ensaio de Imunoadsorção Enzimática , Técnica Indireta de Fluorescência para Anticorpo , Expressão Gênica , Células HeLa , Soros Imunes , Alergia e Imunologia , Imunização , Métodos , Glicoproteínas de Membrana , Genética , Alergia e Imunologia , Proteínas Recombinantes , Alergia e Imunologia , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave , Genética , Alergia e Imunologia , Glicoproteína da Espícula de Coronavírus , Vaccinia virus , Genética , Proteínas do Envelope Viral , Genética , Alergia e ImunologiaRESUMO
In this study, Recombinant baculoviruses rBac-NF and rBac-NG were generated for expressing F and G proteins Nipah virus (NiV) . The expression of recommbinant G (rNG) and F (rNF) protein in rBac-NF and rBac-NG infected cells were confirmed by western-blot. Both rNG and rNF showed sensitive and specific antigenic reaction to rabbit serum anti-Nipah virus in indirect immunofluorescence detection and indirect ELISA. Immunization with rBac-NF and rBac-NG infected insect cells elicited G ad F protein specific antibody responses in mice. Furthermore, the G ad F specific antibodies could neutralize the infectivity of the VSVdeltaG* F/G, the NiV F and G envelope glycoproteins psudotyped recombinant Vesicular Stomatitis Virus expressing green fluorescence protein. The results demonstrated F and G protein expressed by the recombinant baculoviruses could be safe economic diagnostic antigens for the surveillance and monitoring of NiV and promising subunit vaccines for the prevention of NiV.