Porcine deltacoronavirus (PDCoV) has emerged in several pig-raising countries and has been a causative pathogen associated with diarrheal diseases in South Korea since 2014. In the present study, we were able to isolate and cultivate a Korean PDCoV strain (KNU16-07) in cell culture and investigate its pathogenicity. PDCoV-inoculated piglets showed watery diarrhea accompanied by acute enteritis in the natural host. Sequencing analysis demonstrated the genetic stability of KNU16-07 for at least thirty serial passages.
Cell Culture Techniques ; Diarrhea ; Enteritis ; Korea ; Serial Passage ; Virulence

Due to the increased frequency of interspecies transmission of avian influenza viruses, studies designed to identify the molecular determinants that could lead to an expansion of the host range have been increased. A variety of mouse-based mammalian-adaptation studies of avian influenza viruses have provided insight into the genetic alterations of various avian influenza subtypes that may contribute to the generation of a pandemic virus. To date, the studies have focused on avian influenza subtypes H5, H6, H7, H9, and H10 which have recently caused human infection. Although mice cannot fully reflect the course of human infection with avian influenza, these mouse studies can be a useful method for investigating potential mammalian adaptive markers against newly emerging avian influenza viruses. In addition, due to the lack of appropriate vaccines against the diverse emerging influenza viruses, the generation of mouse-adapted lethal variants could contribute to the development of effective vaccines or therapeutic agents. Within this review, we will summarize studies that have demonstrated adaptations of avian influenza viruses that result in an altered pathogenicity in mice which may suggest the potential application of mouse-lethal strains in the development of influenza vaccines and/or therapeutics in preclinical studies.
Animals ; Host Specificity ; Humans ; Influenza A virus ; Influenza in Birds* ; Influenza Vaccines ; Methods ; Mice ; Orthomyxoviridae ; Pandemics ; Serial Passage ; Vaccination ; Vaccines* ; Virulence

BACKGROUND AND OBJECTIVES: Adipose-derived mesenchymal stem cells (ADSCs) are promising candidates in regenerative medicine. The need for in vitro propagation to obtain therapeutic quantities of the cells imposes a risk of impaired functionality due to cellular senescence. The aim of the study was to analyze in vitro senescence of previously cryopreserved human ADSCs subjected to serial passages in cell culture. METHODS AND RESULTS: ADSC cultures from 8 donors were cultivated until proliferation arrest was reached. A gradual decline of ADSC fitness was observed by altered cell morphology, loss of proliferative, clonogenic and differentiation abilities and increased β-galactosidase expression all of which occurred in a donor-specific manner. Relative telomere length (RTL) analysis revealed that only three tested cultures encountered replicative senescence. The presence of two ADSC subsets with significantly different RTL and cell size was discovered. The heterogeneity of ADSC cultures was supported by the intermittent nature of aging seen in tested samples. CONCLUSION: We conclude that the onset of in vitro senescence of ADSCs is a strongly donor-specific process which is complicated by the intricate dynamics of cell subsets present in ADSC population. This complexity needs to be carefully considered when elaborating protocols for personalized cellular therapy.
Aging* ; Cell Aging ; Cell Culture Techniques ; Cell Size ; Humans* ; Mesenchymal Stromal Cells* ; Population Characteristics ; Regenerative Medicine ; Serial Passage ; Telomere ; Tissue Donors

To character a novel chimera(1b/2a) hepatitis C virus cell culture (HCVcc) system carrying envelope E1E2 coding gene from Hebei strain of China, chimera HCVcc (cHCVcc) was developed from Huh7.5-CD81 cells after transfection with in vitro transcribed full-length 1b/2a chimera RNA, which carrying envelope E1E2 coding gene from Hebei strain of China. Then the replication, expression and infectious titer of serial passage HCVcc were assessed by Real Time RT-PCR, indirect immunofluorescence assay (IFA) and Western blotting (WB). In addition, chimeric envelope gene from HCVcc was sequenced after serial passage. We found that the number of HCV positive focus increased gradually in cell post-transfection with chimera HCVcc (1b/2a) RNA and reach a peak platform (80% to 90%) at 41 days post-transfection; the expression of HCV protein was also confirmed by WAB during serial passage. At meantime, HCV RNA copy number in the supernatant peaked at 10(4)-10(7) copies/mL and the highest infectious titer of this 1b/2a cHCVcc reinfection were tested as 10(4) ffu/mL. Sequence analysis indicated 6 of adaptive amino acid substitutes occur among chimeric envelope E1E2 during serial passages. We con:luded that a novel 1b/2a chimera HCVcc carrying envelope E1E2 coding gene from Hebei strain of China was developed and its infectious titer increased after serial passage of HCVcc. This novel cHCVcc will be an effective tool for further evaluation of anti-virus drugs and immune effects against the major genotype from Chinese.
Cell Line ; China ; Hepacivirus ; genetics ; growth & development ; metabolism ; Hepatitis C ; virology ; Humans ; Serial Passage ; Viral Envelope Proteins ; genetics ; metabolism

We wished to select a cold-adapted genotype G1P[8] ZTR-68 rotavirus (China southwest strain) in MA104 cells for possible use as a live vaccine. ZTR-68 was recovered originally from children with diarrhea. The virus was cultivated at 37 degrees C at the first passage. Then, the cultivation temperature was decreased stepwise by 3 degrees C per eight passages. In total, the virus was passaged 32 times, and cultivation was terminated at 28 degrees C. Biological characteristics of the virus were analyzed during serial passages. There was no difference between the migration patterns of genomic dsRNA segments according to polyacrylamide gel electrophoresis of original and cold-adapted viruses. Infectious and red cell-agglutination titers of cold-adapted virus were lower than those of the parent virus. Also, the virus formed small-size plaques with irregular shapes at 31 degrees C and 28 degrees C. These results suggested that a genetically stable attenuated virus can be obtained through serial cold-adapted passages. Thus, an alternative strategy is provided by cold-adaption for development of attenuated live rotavirus vaccines.
Adaptation, Physiological ; China ; Cold Temperature ; Diarrhea ; virology ; Female ; Genotype ; Humans ; Infant ; Male ; Rotavirus ; genetics ; growth & development ; isolation & purification ; physiology ; Serial Passage ; Virus Cultivation ; Virus Replication

To investigate the phenotypic characteristics of the strain of the rabies virus CTNCEC25, the strain of the China rabies virus CTN-1 adapted to primary chicken embryo cells (CECs), Vero cells, and mouse neuroblastoma N2a cells was inoculated with CTNCEC25 and parental CTN-1 strains to explore the cytopathic effect (CPE) and growth kinetics of CTNCEC25 on cultured cells. To determine the pathogenicity of CTNCEC25, suckling mice, adult mice, guinea pigs and rabbits were inoculated with CTNCEC25 via the intracerebral route and their survival monitored every day. Furthermore, the CTNCEC25 strain was passed serially in CECs for 20 passages and then 3 passages in the brains of suckling mice to determine phenotypic stability. CTNCEC25 achieved similar growth kinetics in Vero cells and N2a cells compared with parental CTN-1, but CTNCEC25 replicated more efficiently in CECs than the CTN-1 strain with a titer 72 h after infection reaching 10(7.5-7.6) FFU/mL, which was significantly higher than the 10(5.8) FFU/mL achieved by its parental strain, CTN-1. Moreover, CTNCEC25 induced apparent CPE in Vero cells, CECs and N2a cells. Analyses of intracerebral inoculation demonstrated that CTNCEC25 was attenuated profoundly in adult mice and was completely apathogenic to guinea pigs and rabbits, though it caused death in suckling mice. The CTNCEC25 strain proliferated steadily after serial passage in CECs and the brains of suckling mice, and remained avirulent in adult mice. These results suggest that CTNCEC25 is a highly attenuated and genetically stable strain of the rabies virus. CTNCEC25 replicated stably and efficiently in cultured cells and achieved high titers, so it could be a promising and safe vaccine strain for rabies prevention in China.
Animals ; Cell Line ; Cercopithecus aethiops ; China ; Guinea Pigs ; Humans ; Mice ; Rabbits ; Rabies ; virology ; Rabies virus ; genetics ; growth & development ; pathogenicity ; Serial Passage ; Viral Vaccines ; adverse effects ; genetics ; Virulence

To develop an attenuated vaccine against the highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRS) virus, the HP-PRRS virus strain TJ was attenuated by serial passages and plaque cloned every 5 to 10 passages in Marc-145 cells. Genetic variation and pathogenicity of HP-PRRSV strain TJ in the course of attenuation were analyzed. The results showed that the strain TJ sustained various sequence changes during the course of attenuation. Fifty-eight amino acids changes and a new continuous 120 amino acids deletion after the discontinuous 30 amino acids deletion (sites 481 and 533-561) occurred in strain TJ passages 140, and the position of 120 amino acids deletion was between 628 to 747 according to VR-2332. Animal test showed that the pathogenicity of strain TJ passages 20 was attenuated obviously, so we presume that genetic variation in nonstructural protein nsp2-nsp5, nsp7 and structural protein GP5 during the attenuation provides the molecular bases for the observed attenuated phenotype.
Amino Acid Sequence ; Animals ; Genetic Variation ; Molecular Sequence Data ; Porcine Reproductive and Respiratory Syndrome ; virology ; Porcine respiratory and reproductive syndrome virus ; classification ; genetics ; isolation & purification ; pathogenicity ; Sequence Deletion ; Serial Passage ; Swine ; Vaccines, Attenuated ; genetics ; isolation & purification ; Virulence

OBJECTIVETo investigate the genetic stability during the serial passages of non-replicating recombinant adenoviruses based on the novel AdEasy system.

METHODSFour non-replicating adenoviruses expressing rotavirus antigens, which were generated by the AdEasy system, were used as models and continuously propagated on 293 cells for 20 passages. Samples of the infected cells were collected at every 5 passages for the PCR analysis of the inserted rotavirus genes, replication-competent adenoviruses (RCAs) as well as the Western blot examination of the expression of the certain rotavirus genes.

RESULTSThe adenoviruses can be stably propagated on 293 cells. The existence and the stable expression of inserted rotavirus genes were able to be detected during the serial passage. The RCAs were not found within the first 10 passages, but the rvAdG2VP7(o) at passage 15 and the rvAdG2VP7(o) and rvAdG1VP7(o) at passage 20.

CONCLUSIONThe non-replicating adenoviruses showed promising genetic stability during the continuous passage on 293 cells. The RCAs normally will not be detectable within 10 continuous passages. The results indicated the potential of such recombinant adenoviruses in the research and development of the gene therapies and adenoviral-vectored vaccines.

Adenoviridae ; genetics ; isolation & purification ; physiology ; Cell Line ; DNA, Recombinant ; genetics ; Humans ; Serial Passage ; Transgenes ; Virus Replication

OBJECTIVETo establish a real-time RT-PCR based plasma virus quantification method and monitor the plasma viral load of SHIV-CN97001 during its in vivo passages in rhesus macaques.

METHODSViral RNA standards were prepared by in vitro transcription and one-tube real-time RT-PCR were established and optimized using TaqMan EZ RT-PCR CORE REAGENTS and TaqMan probes and primers directed to the 91 bases within the conserved gag region of SHIV. Plasma viral RNA of 126 plasma samples from rhesus macaques of different viral passages was quantified.

RESULTSThe PCR system was optimized by using serial dilution of standards, and the viral RNA load was detected. The lowest limit of the standard curve reached 2x10(-2) copies/ml. The correlation (r>0.99) and the repetition (CV=4.14 percent) also met the requirement. It was revealed that the viral RNA load of third passage was the highest. Generally, the viral load peaks (10(5)-10(6) copies/ml) appeared at the fourteenth day after the infection or inoculation.

CONCLUSIONThe method of one-tube real-time RT-PCR was established successfully, which may provide a sensitive way to qualify SHIV viral load. This will contribute to the establishment and application of SHIV/rhesus macaque models. It was also found that the replicative ability of SHIV-CN97001 was enhanced during the first 2 in vivo passages.

Animals ; HIV ; genetics ; isolation & purification ; HIV Infections ; virology ; Humans ; Macaca mulatta ; RNA, Viral ; blood ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; methods ; Serial Passage ; Simian Acquired Immunodeficiency Syndrome ; virology ; Simian Immunodeficiency Virus ; genetics ; isolation & purification ; Viral Load

STUDY DESIGN: Establishment of a multipotent neural stem cell line from the adult mouse cerebrum. OBJECTIVES: To establish a daughter cell line, B2A1, from B2 cells through the limiting dilution method, and to determine if the cells have the characteristics of neural stem cell (NSCs) using immunocytochemistry and RT-PCR methods. SUMMARY AND LITERATURE REVIEW: In the development of NSCs, differentiated organ or tissue-derived multipotent stem cells have attracted considerable interest because of the lack of ethical issues. Previously, a glial precursor cell line (B2 cells) was generated from the primary cultures of oligodendrocytes/ astrocytes in an adult BALB/c mouse brain. These cells exhibited the cell-type specific markers for immature neuroectodermal cells, astrocytes, and oligodendrocytes in serum-contained media. MATERIALS AND METHODS: The primary cultures of oligodendrocytes/astrocytes were established from the whole brains of 12 to 16-week-old BALB/c mice from either gender. After 6 months with 25 serial passages, the culture consisted of a morphologically homogeneous cell population, which was designated as B2 cells. A subclone, B2A1, was isolated from B2 cells through two consecutive limiting dilutions. RESULTS: More than 90% of B2A1 cells showed immunopositivity for nestin, a specific marker for NSC. The cells also showed immunopositivity for the neuronal, astrocytic and oligodendroglial markers. These cells expressed the genotypic mRNA messages for both neural progenitor cells and differentiated neuronoglial cells. These positive immunocytochemical reactions and mRNA messages for neuronoglial cells varied according to the extrinsic growth factors used. However, the treatment of extrinsic growth factors did not produce any significant differences in the nestin-immunopositive cells. CONCLUSIONS: B2A1 cells have the immunocytochemical and cytogenetic properties of NSCs, and the capacity to differentiate into neuronoglial cells.
Adult* ; Animals ; Astrocytes ; Brain ; Cell Line ; Cerebrum* ; Cytogenetics ; Ethics ; Humans ; Immunohistochemistry ; Intercellular Signaling Peptides and Proteins ; Mice* ; Multipotent Stem Cells ; Nestin ; Neural Plate ; Neural Stem Cells* ; Neurons ; Nuclear Family ; Oligodendroglia ; RNA, Messenger ; Serial Passage ; Stem Cells