To investigate biological characteristics of the IVpi-189 progeny virus derived from the culture of influenza A virus as a live-attenuated vaccine candidate. Persistent infection of a cultured cell line with influenza A virus (MDCK-IVpi) was established by incubating continuously influenza virus-infected cells at a lower temperature. The infectious progeny virus derived from MDCK-IVpi cells at the 189rd subculture was designated as the IVpi-189 strain of influenza virus. The cytopathic effect induced by IVpi-189 virus was observed under different temperature conditions. The production of infectious progeny virus was examined at 38 and 32 degrees C by plaque titration of cell-associated and released virus. IVpi-189 virus showed cytopathic effect as strong as that of IVwt in infected cell line of MDCK at 32 degrees C. However, when culture temperature was raised to 38 degrees C, the cytopathic effect induced by IVpi-189 virus was delayed and less pronounced. Virus growth in IVpi-189 virus-infected cells at 38 degrees C was significantly reduced as compared with that of IVwt virus, although both viruses yielded nearly equivalent high titers of cell-associated and released virus at 32 degrees C. The reasons of the decreased proliferative ability of IVpi-189 virus at high culture temperature were unrelated with virus inactivation or the release of progeny virus, but associated with the decreased replication of infectious progeny virus in the infected cells. IVpi-189 virus derived from MDCK cells infected persistently with influenza A virus showed biological characteristics as a potential live-attenuated vaccine candidate.
Animals ; Cell Line ; Cytopathogenic Effect, Viral ; Dogs ; Humans ; Influenza A virus ; genetics ; physiology ; Temperature ; Virus Cultivation ; methods ; Virus Replication

Akabane, Aino and Chuzan virus are arthropod-borne (arbo)viruses mainly associated with reproductive failures in cattle. We investigated apoptosis in Vero cells (C-1586) infected with Akabane, Aino and Chuzan virus. The fragmentation of chromosomal DNA was simultaneously detected with the progress of cytopathic effect from 48 hr to 72 hr post infection, depending on viruses. Although the treatment of cycloheximide blocked apoptosis in Vero cells infected with three viruses, actinomycin D did not prevent DNA oligomerization, thus indicating that de novo viral protein synthesis is critical for viral apoptosis. In addition, the activation of caspase-3 was also detected in Vero cells by indirect fluorescent assay. From the present results, it is of future interest whether apoptotic characteristics of these viruses are related to pathogenecity in vivo.
Animals ; Apoptosis/*physiology ; Bunyaviridae/*physiology ; Caspase 3 ; Caspases/metabolism ; Cercopithecus aethiops ; Cytopathogenic Effect, Viral/*physiology ; DNA Fragmentation/physiology ; Dactinomycin ; Enzyme Activation ; Orbivirus/*physiology ; Vero Cells

OBJECTIVETo study the relationship between late mRNA and the cytopathic effect(CPE) and ultrastructural features after human cytomegalovirus (HCMV) infection in vitro.

METHODSHuman embryo fibroblast cells(HEL) were infected with HCMV AD169 strain. The expression of the HCMV late mRNA was measured by semiquantitative RT-PCR, the cytopathic effect (CPE) and the cell ultrastructure were observed by means of light microscopy and electron microscopy, respectively.

RESULTSThe HCMV late mRNA could be detected 12 hours postinfection and increased gradually, but the CPE appeared 48 hours postinfection in HEL cells. The HCMV infected cells exhibited significant mitochondrial enlargement and the number of mitochondrial ridge deletion, the cisternae lumen of endoplasmic reticulum (ER) dilation and vacuolization (at the end age). The mature nucleocapsid could be observed 96 hours postinfection.

CONCLUSIONThe ultrastructural changes have an intimate correlation with the expression of HCMV late mRNA and play an important role in the life circle of the virus. HCMV late mRNA may serve as a indicator of the clinical effect of treatment in active HCMV infection.

Cytomegalovirus ; genetics ; physiology ; Cytopathogenic Effect, Viral ; Embryo, Mammalian ; Endoplasmic Reticulum ; pathology ; virology ; Fibroblasts ; metabolism ; ultrastructure ; virology ; Humans ; Inclusion Bodies ; pathology ; virology ; Mitochondrial Swelling ; RNA, Messenger ; metabolism

OBJECTIVETo evaluate feasibility of inhibiting coxsackievirus B3 (CVB3) infection at cellular, protein and gene levels by using small interfering RNA (siRNA).

METHODSAntiviral activities of siRNAs were evaluated by observing cytopathic effect (CPE), using plaque reduction Western blotting assays and RT-PCR.

RESULTSEight siRNAs were synthesized, among them, SiRNA-2, SiRNA-3, SiRNA-6 and SiRNA-7 which were targeted against sequences located in 2B, VP4, 2A and 3C section of CVB3 genome, were designed to have different effect of inhibiting CVB3 infection in vitro. SiRNA-2 showed the best protective effect, 95 percent inhibition of CVB3 cytopathic effect and plaque forming effect was observed at 0.0001 MOI, viral protein synthesis and replication were inhibited. SiRNA-2 showed 30 percent inhibition of virus at 0.1 MOI, 70 percent inhibition at 0.01 MOI, 88 percent inhibition at 0.001 MOI, and 99 percent inhibition at 0.0001 MOI 48 hours after CVB3 infection.

CONCLUSIONSiRNA could effectively inhibit CVB3 infection in vitro, siRNA-2, which is targeted against sequence in 2B section of CVB3 genome, seemed to be the best one among those synthesized in this study.

Coxsackievirus Infections ; therapy ; virology ; Cytopathogenic Effect, Viral ; drug effects ; Enterovirus ; genetics ; physiology ; HeLa Cells ; Humans ; RNA Interference ; RNA, Small Interfering ; genetics ; therapeutic use ; Virus Replication ; drug effects

To study the proliferation characteristics of PPV in differently infected way and the variance of concentrations in different cells. A strain of porcine parvovirus(PPV) was adapted to PK-15 cells, and a Real-time fluorescent quantitative PCR (FQ-PCR) assay was developed based on the specific region of the NS1 gene of PPV to quantify the PPV. The FQ-PCR was used to measure the viral concentration of virus-infected cells by simultaneous or step by step inoculation and plot one-step growth curves. The proliferation characteristics of PPV strain in different cells lines (HeLa, MDBK, PK-15 ,ST, F81, BHK-21 and Marc-145) was also compared. The results showed the PK-15 cell -adapted strain of PPV produced CPE after 12 passages, and maintained stable CPE at the following 10 messages. The one-step growth curve showed that the virus concentration of simultaneous inoculation was higher than that of the step-by-step inoculation, and the proliferation cycle of step-by-step inoculation was shorter. The proliferation ability of PPV strain in different cells showed that CPE appeared first inPK-15, followed by ST, HeLa and MDBK, and the virus concentration was highest in ST, followed byPK-15, MDBK and HeLa. NO proliferation was observed in F81, BHK-21 and Marc-145 cells. These findings lay a material foundation for the basic researches on PPV and the development of vaccine.
Animals ; Cell Line ; Cricetinae ; Cytopathogenic Effect, Viral ; DNA, Viral ; genetics ; Female ; Haplorhini ; Humans ; Male ; Parvoviridae Infections ; virology ; Parvovirus, Porcine ; genetics ; physiology ; Real-Time Polymerase Chain Reaction ; Reproducibility of Results ; Sensitivity and Specificity ; Swine ; Viral Proteins ; genetics ; Virus Replication