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PubMed1988

Inhibitory effect of parvovirus H-1 on cultured human tumour cells or transformed cells.

The present study establishes the in vitro system for studying the oncosuppression activity of parvovirus and discovers that parvovirus H-1 can be grown cytolytically in various human cancer cell lines, which include 4 hepatoma cell lines (QGY-7703, SMMC-7721, Bel-7402, PLC/PRF/5), 3 gastric cancer cell lines (SGC-7901, MGC-80-3, MKN-28) and 1 naspharynx cancer cell line (CNE). The growth of two primary gastric cancer cell cultures from surgical cancer tissue were also inhibited by the infection of H-1. The sensitivity of cancer cells to H-1 may relate to their differentiation states. On the contrary, H-1 can neither be grown cytolytically in normal liver or stomach cells, nor inhibit their growth. Transformation of human skin fibroblasts with Simian Virus 40 activated their sensitivity to H-1. Our results thus indicate that the antineoplastic activity of H-1 in vivo involves at least its direct inhibiting or killing malignant cells.

Carcinoma, Hepatocellular↗
PubMed2005

Sensitivity of diagnostic tests for influenza varies with the circulating strains.

BACKGROUND: Effective strategies to combat the spread of influenza viruses rely on accurate diagnosis of the infection, which is greatly affected by the sensitivity of the assays used. OBJECTIVES: To determine if the sensitivity of assays used to detect influenza varies with the viral strains. STUDY DESIGN: This prospective study used 142 respiratory specimens submitted to the clinical virology laboratory during the 2003/2004 influenza season, when the H3N2 Fujian strain was first detected in our community, to assess sensitivities of rapid immunoassay (RIA), shell-vial (SV), hemadsorption (HA)-, and fluorescent antibody (FA)-based conventional tissue culture (TC). Results were compared with similar evaluations performed in 2002/2003 or earlier seasons. RESULTS: Sensitivities of RIA, SV, HA-TC, and FA-TC were 44, 70, 82, and 100%, respectively for influenza virus circulating in 2003/2004. The comparison with results obtained in previous influenza seasons showed a significantly decreased sensitivity of HA-TC (p=0.02) and lower sensitivity of RIA but without reaching statistical significance (44% versus 72%, p=0.2). CONCLUSIONS: This report underscores the importance of determining the accuracy and sensitivity of diagnostic tests against emerging influenza variant strains.

Antigens, Viral↗
PubMed1988

Sensitization of transformed rat fibroblasts to killing by parvovirus minute virus of mice correlates with an increase in viral gene expression.

Cultures of established rat fibroblasts transformed by the avian erythroblastosis virus were more susceptible to the cytopathic effect of the autonomous parvovirus minute virus of mice, prototype strain (MVMp), than were their untransformed homologs. This effect could be ascribed to the presence of a greater fraction of cells that were sensitive to the killing action of MVMp in transformed cultures than in their normal parents. Yet, transformed and normal lines were similarly efficient in virus uptake, DNA amplification, and capsid protein synthesis. In contrast, transformants accumulated 2.5- to 3-fold greater amounts of all three major MVM mRNA species and nonstructural protein than did their normal progenitors. Thus, in this system transformation-associated sensitization of cells to MVMp appears to correlate primarily with an increase in their capacity for the expression of the viral transcription unit which encodes nonstructural proteins and is controlled by the P4 promoter. Consistently, a reporter gene was expressed at a higher level by transformed versus normal cultures, when placed under the control of the MVM P4 promoter. As infectious MVMp was produced in larger amounts by transformed cultures, a late step of the parvoviral cycle, such as synthesis, encapsidation of progeny DNA, or both, was also stimulated in the transformed cells.

Alpharetrovirus↗
PubMed1990

Anti-retrovirus activity of 9-(2-phosphonylmethoxyethyl)adenine (PMEA) in vivo increases when it is less frequently administered.

Different treatment schedules have been investigated when evaluating the inhibitory effect of 9-(2-phosphonylmethoxyethyl)adenine (PMEA) and 3'-azido-2',3'-dideoxythymidine (AZT) on the replication of human immunodeficiency virus type I (HIV-I) in MT-4 cells, transformation of C3H/3T3 cells by Moloney murine sarcoma virus (MSV), and MSV-induced tumor formation in newborn NMRI mice. Shortening the exposure time of HIV-I-infected MT-4 cells to PMEA or AZT led to an increase in the selectivity index of both compounds. PMEA proved markedly more efficient in suppressing MSV-induced tumor formation in mice when administered as a single dose on the day of infection than when these doses were spread over 2, 4 or 7 administrations within 1 week after the virus infection. This was not observed when the total dose of AZT was fractionated. While the infrequent dosage regimen increased the anti-retrovirus activity of PMEA, it did not increase its toxicity for the host. This unique property makes PMEA an attractive candidate for the treatment of retrovirus infections, including AIDS.

Adenine↗
PubMed1989

Morphological changes in HAV-infected Frp/3 cells and immunolocalization of HAAg.

Electron and immunoelectron microscopic studies were carried out on HAV-infected Frp/3 cells. The infection led to a distinctive cytopathic effect (CPE) arising on day 3 up to the complete detachment of monolayers on day 7. Infected cells exhibited progressive modifications, beginning from the formation of long helical polyribosomes. Subsequently, hypertrophy, cisternal dilatation and degranulation of the RER could be observed. Furthermore, the formation of concentric membranous bodies (CMB), large myelin-like structures and annulate lamellae could be revealed at later times of infection. 24-27 nm virus-like particles were observed within cytoplasmic vesicles or outside extensively degenerated cells. Indirect immunoperoxidase staining were used to localize HAV antigen (HAAg) in thin sectioned infected Frp/3 cells. Vesicular inclusion bodies, often seen to contain electron-lucent particles, resulted darkly stained as well as tracts of the RER and myelin-like structures. Negatively stained preparations from cell lysates revealed small clusters of HAV particles which sometimes appeared to be still associated with residual membrane fragments. Our findings seem to suggest that HAV replication occurs in close association with cytoplasmic membranes and a direct involvement of the RER seems to be demonstrated.

Antigens, Viral↗
PubMed1986

Impact of revaccinating children who initially received measles vaccine before 10 months of age.

Two hundred fifty-four infants who had received measles vaccine at less than 10 months of age were revaccinated at greater than or equal to 15 months of age, and their immune responses were compared with 129 control infants who received their first doses of measles vaccine at greater than or equal to 15 months of age. Sera were collected at the time of revaccination (study infants) or primary vaccination (control infants), 3 weeks, and 8 months later and tested for antibody by hemagglutination inhibition (HI), enzyme-linked immunosorbent assay (ELISA), and cytopathic effect neutralization (CPEN). Of the 121 study infants who were initially HI negative, 116 (95.9%) made HI antibody 3 weeks postrevaccination compared with 126 (99.2%) of 127 control infants (P = 0.19). Of the 63 study infants with no initial detectable antibody by any of the three tests, 14 (22.2%) had a measles-specific IgM response 3 weeks postrevaccination compared with 37 of 50 (74.0%) randomly chosen control infants. By 8 months after revaccination, the 121 initially HI-negative study infants were significantly less likely to have detectable HI antibodies than control infants (52.1% v 97.6%) (P less than .001). However, 96.7% of these 121 study infants had detectable neutralizing antibody 8 months postrevaccination, an antibody thought to correlate best with protection. This study confirms the altered immune response to revaccination in infants first vaccinated prior to 10 months of age; however, the data suggest that most of these infants were successfully primed and are probably protected after revaccination.

Age Factors↗
PubMed1987

Characteristics of a novel lentivirus derived from South African sheep with pulmonary adenocarcinoma (jaagsiekte).

A novel lentivirus was isolated from South African sheep with experimentally transmitted lung adenocarcinoma. Similar to visna virus and caprine arthritis encephalitis virus, this new strain induced cytopathic effects on ovine plexus choroid cultures. In contrast to a recent Israeli isolate from sheep with adenocarcinoma, the South African lentivirus could not transform fibroblast cultures. The antigenic relatedness between the new isolate and visna virus was assessed by immunoprecipitation of radiolabeled viral proteins, using monospecific antisera against visna virus proteins. The results indicate that the new virus contains four major structural proteins of sizes similar to those of visna virus (i.e., gp135, p30, p16, and p14) and have some common antigenic determinants (about 90% in the major core antigen p30). However, the nucleotidic sequences of the novel lentivirus were found to be only 16.5 to 27.4% homologous to visna virus and 8.3 to 15% homologous to caprine arthritis encephalitis virus, by means of liquid hybridization under stringent conditions. The genetic divergence indicated by this last result was confirmed by the dissimilar restriction endonuclease cleavage map of the new virus in comparison to those of visna virus and three caprine arthritis encephalitis virus strains. The demonstration of a third type of ovine lentivirus supports the concept of an important genetic variation among the lentiviruses infecting one animal species.

Animals↗
PubMed1981

Use of a feline cell line in the syncytia infectivity assay for the detection of bovine leukemia virus infection in cattle.

This report describes a modified syncytia infectivity assay (SIA) for the direct detection of bovine leukemia virus (BLV) in blood lymphocytes of cattle, using transformed feline (CC81) cells as the indicator system. The data show that the syncytia present in cultures of CC81 cells inoculated with BLV-infected cells are specific and arise through a mechanism similar to that responsible for the phenomenon of "late" polykaryocytosis described in other virus systems. The susceptibility of the CC81 cells to the syncytia-inducing effect of BLV-infected cells is comparable with that of early passages of bovine embryonic spleen cells, which were previously used as the indicator system in the SIA. Unlike the bovine embryonic spleen cells, CC81 cells retain their susceptibility to syncytia induction for long periods of cultivation. Furthermore, the syncytia induced in the CC81 cultures are larger and easier to identify. Thus, the CC81 cells can be used advantageously as the indicator system when the SIA is applied to the detection of BLV-infected lymphocytes. The results of the SIA for the detection of infective BLV agreed closely with those of the radioimmunoassay for the detection of BLV antibodies in randomly examined cattle. On the other hand, many cattle in early stages of infection were positive in the radioimmunoassay several months before they reacted in the SIA. The detection of BLV in blood lymphocytes provides a useful method for the diagnosis of BLV infection in cattle when serologic tests cannot be used, eg, calves that may have passively acquired maternal antibodies and cattle given BLV vaccines.

Animals↗
PubMed1973

Equine herpesviruses: antigenic relationships and deoxyribonucleic acid densities.

Equine herpesviruses with a deoxyribonucleic acid density of 1.716 to 1.717 g/cm(3) were compared with one another by the plaque-reduction test and by the rate of development of cytopathic effect as indicated by plaque size in rabbit kidney cultures. Of the 19 isolates studied, the 9 which had already been tentatively labeled equine abortion viruses were serologically similar to one another; each of them grew more quickly than did any of the other 10 isolates although the mean plaque sizes formed a series of gradations with no clear hiatus which would permit the unequivocal delineation of the abortion viruses from the slowly growing strains. The 10 slowly growing isolates showed antigenic heterogeneity even though complement was present; the neutralizing capacity of an antiserum against the heterologous strains was, in most instances, markedly less than against the homologous strains, the range of the 50% endpoints being much greater than that observed among the equine abortion viruses, or among isolates of herpes simplex type 1. There was no cross neutralization between the equine abortion viruses and any of the 10 slowly growing isolates. An extra band of deoxyribonucleic acid, at 1.723 to 1.725 g/cm(3), was present in two of the slowly growing strains when originally grown in rabbit cells, but was no longer present after passage in cat cells. This band occupied the same position as one reported in the hamster-passaged strain of equine abortion virus, and had a density similar to that of the equine genital herpesvirus. Although the taxonomic demarcation of the equine abortion viruses and the slowly growing herpesviruses from one another is still open to question, they can be conveniently labeled equine herpesviruses 1 and 2, respectively; the genital virus would be termed equine herpesvirus 3.

Animals↗
PubMed1995

The roles of perforin- and Fas-dependent cytotoxicity in protection against cytopathic and noncytopathic viruses.

In vitro, T cell-dependent cytotoxicity is mediated by two distinct mechanisms, one being perforin-, the other Fas-dependent. The contribution of both of these mechanisms to clearance of viral infections was investigated in mice for the non-cytopathic lymphocytic choriomeningitis virus (LCMV) and the cytopathic vaccinia, vesicular stomatitis (VSV) and Semliki forest (SFV) viruses. Clearance of an acute LCMV infection was mediated by the perforin-dependent mechanism without measurable involvement of the Fas-dependent pathway. For the resolution of vaccinia virus infection and for resistance against VSV and SFV, however, neither of the two pathways was required. These data suggest that perforin-dependent cytotoxicity mediated by T cells is crucial for protection against non-cytopathic viruses, whereas infections with cytopathic viruses are controlled by nonlytic T cell-dependent soluble mediators such as cytokines (IFN-gamma against vaccinia virus) and neutralizing antibodies (against VSV and SFV).

Alphavirus Infections↗
PubMed1985

Transforming potential of a retrovirus isolated from lung carcinoma of sheep.

A retrovirus isolated from experimentally induced sheep lung carcinoma (SPCTV) was propagated in chronically infected Himalayan tahr ovarian cells and in normal sheep lung cells. Follow-up of infection of the cells with SPCTV showed the appearance of syncytium, plaque formation, partial recovery and the establishment of a chronic infection. Virus-associated reverse transcriptase activity in the medium fluctuated but remained at a constantly high level at the stage of chronic infection. Stages of type-C virus morphogenesis were demonstrated by electron microscopy. The viral genome was detected in both the nucleus and cytoplasm by in situ hybridization. Chronically infected cells formed colonies when plated in soft agar. Following subcutaneous inoculation of chronically infected cells (of fibroblast origin) into nude mice, lymphoid tumors developed at the site of inoculation and in vital organs.

Agar↗
PubMed1978

A nonlytic transforming mutant of herpes simplex virus type 2.

A small-plaque mutant (NO.69) of herpes simplex virus type 2 (HSV-2) strain 333 has been previously isolated and characterized in this laboratory. This mutant was shown to produce a high ratio of noninfectious to infectious particles when grown at the nonpermissive temperature in hamster embryo fibroblasts [Westmoreland D. and Rapp F. (1976). Journal of Virology [8:92--102]. In this study, we have demonstrated that it is possible to obtain noninfectious stocks of this virus which retain transforming ability in a biochemical transformation assay specific for detection of the HSV gene for thymidine kinase. This mutant contains a DNA genome that has a density identical to the DNA of wild-type virus. Virus and cell DNA synthesis after infection with the mutant at both the permissive and nonpermissive temperature are similar to that observed in cultures infected with the parental virus. Clones of mouse cells biochemically transformed by this virus contain HSV antigens and are presently being examined for oncogenicity.

Cell Line↗
PubMed1989

Comparison of different methods for detecting human immune deficiency virus in human immunodeficiency virus-seropositive hemophiliacs.

Since the detection of antibodies against the human immune deficiency virus (HIV) does not definitely prove HIV infection in hemophiliacs, virus detection was attempted by virus isolation from the peripheral blood monocytes (PBL), by demonstration of p24 antigen and decline of p24 antibody, and by detection of viral DNA by the polymerase chain reaction (PCR). Virus isolation was optimized by immediate coculture of PBL and by replacement of the reverse transcriptase test by the p24 antigen test, whereas the elimination of CD8+ lymphocytes proved to be unnecessary. Virus detection was dependent on the clinical stage of the illness. Virus isolation in 70 of 211 patients (33%) was more sensitive than detection of p24 antigen or decline of p24 antibody. PCR was performed in 25 patients and indicated infection in all of 15 isolation-positive cases and in 6 of 10 patients from whom virus was not isolated. Changes from negative to positive virus culture and from a weakly fusiogenic to a highly fusiogenic isolate were often accompanied by a progression of the disease. The results suggest that reactivation of HIV occurs when immune deficiency has become manifest. Apparently virus isolation detects only the virus already reactivated in vivo, whereas the PCR may also detect latent virus.

Antibodies, Viral↗
PubMed1992

The synergistic neutralization of Rift Valley fever virus by monoclonal antibodies to the envelope glycoproteins.

A panel of monoclonal antibodies (MAbs) mapping to different antigenic sites on the RVFV G1 and G2 proteins were used to examine the mechanisms involved in neutralization of the virus. Three types of synergistic neutralization of RVFV were observed on mixing various pairs of MAbs. Firstly, enhanced neutralization occurred for two MAb pairs that showed augmented binding for G2. These comprised a combination of a neutralizing MAb with a non-neutralizing antibody, as well as two antibodies which were non-neutralizing individually. In the second category, synergistic neutralization was observed between combinations of MAbs for which increased binding had not been detected. Lastly, mixtures of G1 and G2-specific MAbs were also capable of enhancing neutralization. Post-adsorption neutralization assays revealed that some MAbs neutralized cell-attached virus efficiently, indicating that they can neutralize by inhibiting the infection process after virus attachment. MAbs mapping to G1 IIe, G2I b and G2I c were unable to neutralize adsorbed virus and thus probably neutralize by preventing virus attachment to cells. Several G1-reactive MAbs displayed low level post-adsorption activity, suggesting they may be capable of inhibiting RVFV infectivity at different stages of the replication cycle.

Adsorption↗
PubMed1984

Inability of various immune mechanisms to establish in vitro latent infection in sensory neurons infected by HSV-1. Brief report.

Various immune mechanisms were tested for their ability to alter a normally productive infection of herpes simplex virus in cultures of dissociated rat sensory neurons. These mechanisms included anti-HSV antibody with and without the aid of complement, HSV-sensitized "T" cells, natural killer cells, and "K" cells plus anti-HSV antibody (ADCC reactions). Although both anti-HSV antibody plus complement and the ADCC mechanism significantly limited infectious HSV production, no mechanism was capable of preventing the eventual infection of the majority of neurons. It appears, therefore, that none of these mechanisms by themselves can convert a normally productive infection of sensory neurons in culture to a non-productive or latent infection.

Animals↗