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Biomedical subjects

Z F Fu

Publications and source records attributed to Z F Fu.

At least 37 records · Page 2Linked to original sources
PubMed1994

Rabies ribonucleocapsid as an oral immunogen and immunological enhancer.

The administration of rabies ribonucleocapsid (RNP) by oral as well as parenteral routes was found to prime specific T cells and elicit N-protein-specific antibodies. per os and intramuscular immunization led to the production of antibodies of the IgA and IgG isotypes, respectively. Mice primed orally with RNP produced significantly enhanced amounts of virus-neutralizing antibody, compared with non-immune controls, upon subsequent parenteral booster immunization with inactivated rabies virus. Thus oral immunization with rabies RNP primed cells capable of mediating a secondary systemic response to rabies virus. The results of experiments in which peptide and protein antigens were administered either physically coupled to or mixed with RNP indicate that RNP has an inherent capacity to enhance immune responses.

Adjuvants, Immunologic↗
PubMed1994

Both the N- and the C-terminal domains of the nominal phosphoprotein of rabies virus are involved in binding to the nucleoprotein.

The interaction of the nominal phosphoprotein (NS) and the nucleoprotein (N) of rabies virus (Evelyn Rokitnicki Abelseth strain) was investigated by expressing these proteins in insect cells and in an in vitro coupled transcription-translation system. The N and NS proteins individually expressed in insect cells interacted with each other in vitro and formed complexes at a N:NS ratio similar to those found in rabies virions. In the in vitro transcription-translation system, both the N and NS proteins when synthesized simultaneously formed N-NS complexes which could be immunoprecipitated with either anti-N or anti-NS antibodies. NS mutant proteins with C-terminal deletion of up to 166 amino acids were still able to form complexes with N protein when synthesized simultaneously. However, when the NS mutant proteins and the N protein were synthesized individually and then mixed together, only the intact NS protein and NS mutant protein with 24 amino acids deleted from the C-terminus bound to the N protein, whereas deletion of 47 or more amino acids from the C-terminus of the NS protein resulted in total loss of binding to the N protein. NS mutants with N-terminal deletions of up to 68 amino acids bound to the N protein when synthesized either simultaneously or individually. These results indicate that both the N- and C-terminal domains of the NS protein of rabies virus are involved in the binding to rabies virus N protein but not in a mutually dependent manner. The interaction of the N-terminal domain of the NS protein with N protein occurs only during simultaneous synthesis of both proteins, whereas the C-terminal region of the NS protein can bind to the N protein when these two proteins are synthesized either simultaneously or separately. The two binding sites of the NS protein to N protein might have important functions in regulating virus transcription and replication as well as in virus assembly.

Base Sequence↗
PubMed1994

Long-term humoral and cellular immunity after vaccination with cell culture rabies vaccines in man.

To determine the duration of anti-rabies immunity, peripheral blood of 18 vaccinees was obtained between 2 and 14 years after immunization. Peripheral blood mononuclear cells (PBMC) and serum were tested for the presence of either rabies virus-specific antibodies or rabies antigen-specific proliferation. Neutralizing immunoglobulin class G anti-rabies virus antibodies could be detected in sera of all vaccinees, but not in 18 age- and sex-matched controls. Rabies antigen-induced proliferation of PBMCs from vaccinees was significantly higher than that of controls. The anti-rabies T and B cell response showed no time-dependent pattern. These results suggest the induction of a long-term immunity after rabies immunization according to pre- and post-exposure schedules with inactivated cell culture vaccines against rabies.

Adult↗
PubMed1994

Development of human monoclonal antibodies to rabies.

A total of nine human monoclonal antibodies (MAbs) to rabies virus were generated from peripheral B lymphocytes of subjects immunized with human diploid cell rabies vaccine by somatic cell hybridization. The MAbs were analyzed for their antigen-binding specificities using ELISA, Western blot, and immunoprecipitation assays. The different assays made it possible to identify MAbs directed to the surface glycoprotein, nucleoprotein, nominal phosphoprotein, and matrix protein. One of the MAbs that recognized the surface glycoprotein neutralized rabies virus.

Antibodies, Monoclonal↗
PubMed1993

In vivo expression of inducible nitric oxide synthase in experimentally induced neurologic diseases.

The purpose of this study was to investigate the induction of inducible nitric oxide synthase (iNOS) mRNA in the brain tissue of rats and mice under the following experimental conditions: in rats infected with borna disease virus and rabies virus, in mice infected with herpes simplex virus, and in rats after the induction of experimental allergic encephalitis. The results showed that iNOS mRNA, normally nondetectable in the brain, was present in animals after viral infection or after induction of experimental allergic encephalitis. The induction of iNOS mRNA coincided with the severity of clinical signs and in some cases with the presence of inflammatory cells in the brain. The results indicate that nitric oxide produced by cells induced by iNOS may be the toxic factor accounting for cell damage and this may open the door to approaches to the study of the pathogenesis of neurological diseases.

Amino Acid Oxidoreductases↗
PubMed1993

Detection of antibodies against Borna disease virus in sera and cerebrospinal fluid of horses in the USA.

Sera from 295 horses in the USA were examined by an indirect immunofluorescence assay and Western blot assays to determine the prevalence of Borna disease virus infection. Eight (2.7 per cent) of the samples were positive in both assays, and 18 (6.1 per cent) were positive only in the Western blot assay. The indirect fluorescence titres ranged from 1:20 to 1:80 of antibodies recognising the virus-specific antigen from Borna disease virus-infected cells. The purified virus-specific proteins isolated from infected rat brains were recognised by positive equine serum samples after immunostaining by a Western blot technique. Information obtained from the owners about the history of the seropositive horses revealed that they were either clinically normal or had a pathological diagnosis of disease unrelated to Borna disease. This is the first report of the detection of antibodies to Borna disease virus in horses in the USA. The disease may be more widespread in a subclinical form, with very long incubation periods, and may not necessarily be restricted to historically endemic areas.

Animals↗
PubMed1993

Detection of Borna disease virus-reactive antibodies from patients with affective disorders by western immunoblot technique.

Borna disease (BD) virus is a partially characterized neurotropic agent with a predilection for neurons and astrocytes in the limbic system and cerebrum of infected hosts. Although it usually causes a fatal encephalitis, some laboratory animals which have been experimentally inoculated can develop a persistent non-fatal infection characterized by a neuro-behavioral syndrome akin to human manic-depression. Using immunofluorescent techniques, we previously observed BD virus-specific antibodies in the sera of 4.5% of affectively ill patients, with the highest titers present in bipolar patients. More recently, we have developed a sensitive Western blot assay for the detection of anti-BD virus antibodies to a 38/40 kDa and 24 kDa protein in human serum. In the present study, we screened 138 affectively ill patients and 117 healthy controls and observed a significantly great proportion of patients with antibodies to the 38/40 kDa protein (P < 0.0001), the 24 kDa protein (P < 0.05) and both the 38/40 kDa and 24 kDa proteins (P < 0.025). These data extend prior reports on the presence of BD virus-specific antibodies in psychiatric patients, and suggest that a BD virus-like agent may be associated with affective illness in humans.

Adult↗
PubMed1993

Oral vaccination of racoons (Procyon lotor) with baculovirus-expressed rabies virus glycoprotein.

Successful field oral vaccination and protection against viral diseases have so far been achieved only with live-attenuated or live-recombinant virus vaccines. In this communication, we present data that demonstrate that a glycoprotein derived from recombinant baculovirus-infected insect cells is efficacious as an oral vaccine. The glycoprotein (G) of rabies virus (Evelyn Rokitnicki Abelseth strain) was abundantly expressed in a baculovirus expression system and oral vaccination of racoons with the baculovirus-expressed G protein resulted in the production of rabies virus-neutralizing antibodies and protection against a lethal challenge with a street rabies virus. The potential for using the baculovirus-expressed G protein for oral immunization of wildlife is discussed.

Administration, Oral↗
PubMed1993

Severity of neurological signs and degree of inflammatory lesions in the brains of rats with Borna disease correlate with the induction of nitric oxide synthase.

The putative role of nitric oxide in the neuropathogenesis of Borna disease was investigated by determining changes in the expression of inducible nitric oxide synthase (iNOS) mRNA and constitutively expressed NOS (cNOS) mRNA in brains of Borna disease virus (BDV)-infected rats. iNOS mRNA was not detected in normal rat brain but was identified in BDV-infected brain at 14 days postinfection (p.i.), reaching maximum levels at 21 days p.i., when neurological signs and inflammatory reactions in the brain were also at a peak. cNOS mRNA was expressed in both normal brain and infected brain, increasing markedly at 17 days p.i. and reaching a peak at 21 days p.i. In situ hybridization analysis revealed iNOS mRNA in some, but not all, BDV-infected regions of the brain, particularly in the basolateral cortex and the hippocampus. iNOS-positive cells, as identified immunohistologically, were preferentially localized in perivascular areas of the hippocampus and in outer cortical layers. These iNOS-positive cells resembled monocytes/macrophages in morphology and distribution pattern but were significantly fewer. The correlation of iNOS and cNOS mRNA expression with the development of neurological disease, as well as the enhanced expression of iNOS within brain regions with inflammatory lesions, strongly suggests that NO may contribute to pathogenesis of Borna disease.

Amino Acid Oxidoreductases↗
PubMed1993

Differential effects of rabies and borna disease viruses on immediate-early- and late-response gene expression in brain tissues.

In situ hybridization and Northern blot analysis were used to examine expression of the immediate-early-response genes (IEGs) egr-1, junB, and c-fos, and the late response gene encoding enkephalin in the brains of rats infected intranasally with Borna disease virus (BDV) or rabies virus. In both Borna disease and rabies virus infections, a dramatic and specific induction of IEGs was detected in particular regions of the hippocampus and the cortex. Increased IEG mRNA expression overlapped with the characteristic expression patterns of BDV RNA and rabies virus RNA, although relative expression levels of viral RNA and IEG mRNA differed, particularly in the hippocampal formation. Furthermore, the temporal relationship between viral RNA synthesis and activation of IEG mRNA expression in BDV infection differed markedly from that in rabies virus infection, suggesting that IEG expression is upregulated by different mechanisms. Expression of proenkephalin (pENK) mRNA was also significantly increased in BDV infection, whereas in rabies virus infection, pENK mRNA levels and also the levels of glyceraldehyde-3-phosphate dehydrogenase mRNA were reduced at terminal stages of the disease, probably reflecting a generalized suppression of cellular protein synthesis due to massive production of rabies virus mRNA. The correlation between activated IEG mRNA expression and the strong increase in viral RNA raises the possibility that IEG products induce some phenotypic changes in neurons that render them more susceptible to viral replication.

Animals↗
PubMed1992

Delineation of putative mechanisms involved in antibody-mediated clearance of rabies virus from the central nervous system.

The in vitro biological activities of several rabies virus-neutralizing monoclonal antibodies (mAbs) were compared with their ability to prevent a lethal rabies virus encephalomyelitis. The protective activity of a particular mAb in vivo did not correlate with its virus-neutralizing activity in vitro; rather it was related to the mAb's ability to inhibit virus spread from cell to cell and to restrict rabies virus RNA transcription. Since treatment of rabies virus-infected cells with virus-neutralizing mAbs results in an endocytosis of the antibody, we hypothesize that an antibody may exert its inhibitory activity even after uptake by the cell. Post-exposure treatment of rats with a mAb that inhibited both virus spread and virus RNA transcription in vitro resulted in viral clearance from the central nervous system and protected the animals against a lethal rabies virus infection.

Actins↗
PubMed1992

Production of a functional monoclonal antibody recognizing human colorectal carcinoma cells from a baculovirus expression system.

The light and heavy chain cDNA of a murine monoclonal antibody (MoAb) with specificity for human colorectal carcinoma cells have been expressed separately, together, and as a dual construct in insect cells infected with recombinant baculoviruses. High levels of the MoAb were expressed under the control of the polyhedrin promoter. The antibody maintained its specific binding to human colorectal carcinoma cells and mediated lysis of these cells by human lymphocytes, monocytes, and murine macrophages, as determined in antibody-directed cellular cytotoxicity (ADCC) assays. The recombinant immunoglobulin (Ig), like its ascitic counterpart, did not mediate lysis by either human or rabbit complement. The expression of a recombinant antibody exhibiting both functional binding site and Fc region capacities shows that the baculovirus system could be employed in the production of therapeutic Ig.

Animals↗
PubMed1991

Rabies virus nucleoprotein expressed in and purified from insect cells is efficacious as a vaccine.

A cDNA copy of the RNA gene that encodes the nucleoprotein N of rabies virus Evelyn-Rokitnicki-Abelseth strain was cloned into baculovirus. The recombinant baculovirus expressed the N protein abundantly in Spodoptera frugiperda cells. The N protein was extracted from infected Spodoptera frugiperda cells and purified to near homogeneity by affinity chromatography. The purified N protein reacted with 31 of 32 monoclonal antibodies that recognize native rabies virus ribonucleoprotein. Like the ribonucleoprotein, the purified N protein was a major antigen capable of inducing virus-specific helper T cells. Priming of mice with the purified N protein prior to a booster inoculation with inactivated Evelyn-Rokitnicki-Abelseth virus vaccine resulted in a 20-fold increase in the production of virus-neutralizing antibodies. After immunization with the purified N protein, mice developed a strong anti-ribonucleoprotein antibody response and were protected against a lethal challenge of rabies virus. These data indicate that the N protein expressed in insect cells is antigenically and immunogenically comparable to the authentic rabies virus ribonucleoprotein and therefore represents a potential source of an effective and economical vaccine for large-scale immunization of humans and animals against rabies.

Animals↗
PubMed1991

A longitudinal study of natural infection of piglets with Streptococcus suis types 1 and 2.

Streptococcus suis types 1 and 2 were detected in nasal swabs taken from five litters of piglets sampled twice weekly from birth. The two types had been detected in all pigs by the time they were 38 and 25 days old respectively with mean ages of first detectable infection being 13.5 and 8.5 days. The prevalence of infection was not affected by housing conditions or the population density of pigs. Piglets originating from a sow with vaginal swabs positive for S. suis type 2 were infected earlier than piglets from non-vaginal carriers. It is concluded that infection of piglets with S. suis type 2 may occur during the birth process.

Animals↗
PubMed1990

Transfer of maternal antibody against group A rotavirus from sows to piglets and serological responses following natural infection.

An enzyme-linked immunosorbent assay (ELISA) was developed for the measurement of antirotaviral antibody in sera and faeces from pigs and used to study the dynamics of antirotaviral antibody responses in three cohorts of pigs. Piglets acquired antirotaviral antibody by sucking their dams soon after birth. Antirotaviral antibodies of IgA and IgG classes were detected in both colostrum and milk of all sows tested but IgM class antibodies were not. The antibody levels in colostrum were eight to 32 times higher than those in milk which was collected 18 days post partum. The levels of antibody in piglets' sera were comparable to those in colostrum but declined quickly to low levels by one month old. Maternal antibody was also detected in the faeces of piglets up to 18 days old. Natural rotavirus infection occurred in each of these cohorts when the geometric mean ELISA titres of maternal antibody in their sera declined to 1/1600 (by days 21, 25 and 30 for cohorts 1, 2 and 3, respectively). However, a positive correlation was not obtained between the levels of antirotaviral antibody and protection in individual litters within each of the cohort groups. In each of the cohorts, rotavirus infection usually occurred in one or two piglets first and then spread to other piglets in the same cohort. It is therefore suggested that maternally derived antibody is protective against rotavirus infection in piglets only for the first one or two weeks. Following natural infection with rotavirus, increases in serum antibodies were detected in two of the three cohorts by 20 to 30 days after the average time of onset of faecal shedding of virus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Detection and survival of group A rotavirus in a piggery.

Samples of dust, faeces and effluent were collected from a piggery and examined for group A rotavirus, using a commercial ELISA test, electron microscopy and inoculation of MA-104 cells. Rotavirus antigen was demonstrated in samples collected from farrowing and weaner rooms but not from fattener and sow houses. Rotavirus antigen was also detected in samples collected from a weaner room which had been free of piglets for three months. A cytopathic porcine rotavirus (British isolate SW20/21) was kept at room temperature for four months; it survived with titres reduced by 2 log10. These observations suggest that the environment of commercial piggeries is an important source of rotaviral infection for young piglets.

Animals↗
PubMed1989

Isolation of a reovirus from a broiler chicken flock with high early mortality.

A reovirus was isolated from a flock of 12,000 broiler chickens which experienced a total mortality of 6.3% up to 35 days. The reovirus produced large syncytia in primary chicken kidney cell cultures with eosinophilic intracytoplasmic inclusion body formation. Infected cells reacted with fluorescein conjugated specific anti-reovirus serum. Negatively strained virions had a double shelled appearance with overall diameter of 65 to 70 nm. The nucleic acid had ten discrete segments with electrophoretic mobilities as would be expected for a reovirus.

Journal Article↗