Effect of exogenous interferon on rubella virus production in carrier cultures of cells defective in interferon production

An established cell line (Vero) defective in interferon production was used to evaluate the role of interferon in chronic rubella virus infections of cell cultures. Inoculation of Vero cells with a low multiplicity of virus resulted in the development of carrier cultures which had the characteristics of a regulated infection. Although added interferon did not alter rubella virus production in carrier cultures of cells capable of producing interferon, such added interferon caused a dramatic reduction of virus production in the carrier cultures of Vero cells. There was a reduction of the fraction of cells producing virus in Vero carrier cultures, but not in carrier cultures of other cells upon incubation in the continual presence of rubella virus antibodies. In addition, the fraction of infected cells fluctuated in carrier cultures in Vero cells. The data indicate that interferon is not necessary for maintaining a chronic rubella virus infection in vitro and suggest an instability of the virus genome in Vero cells.

Hepatitis B virus harboring nucleotide deletions in the core promoter region and genotype B correlate with low viral replication activity in anti-HBe positive carriers

BACKGROUND

Emergence of anti-HBe following seroconversion of HBe antigen indicates reduced hepatitis B virus (HBV) replication in the liver and low infectivity in the natural course of infection. However, some patients show continued replication or reactivation even in the presence of anti-HBe.

OBJECTIVE

To clarify the cause of HBV replication, we investigated genotype differences and mutations in the core promoter and precore region in relation to virus titer.

STUDY DESIGN

Using quantification of HBV DNA, nucleotide sequencing of the core promoter and precore region, and genotyping with the S gene by restriction fragment length polymorphism (RFLP), we analyzed sera of 26 anti-HBe positive carriers (28 serum samples).

RESULTS

Various mutations were detected including C to T point mutation at nt 1653, A to T and G to A contiguous point mutations at nt 1762 and 1764 in the core promoter region, and G to A point mutation at nt 1896 in the precore region, but no common mutations were detected that were directly related to the virus titer from earlier reported mutations. In contrast, the mean titer of genotype B virus was 1.5 x 10(5) copies per ml and that of mutant HBV of genotype C having 8 base pairs (8-bp) deletion (nt 1768-1775) in the core promoter region was 7.9 x 10(4) copies per ml (mean titer). These titers showed commonly lower than that of genotype C virus without 8-bp deletion (median titer 5.0 x 10(6) copies per ml). Transition of genotype from C to B after viral reactivation and reduction of proportion of 8-bp deletion mutant at reactivation period was observed in a patient who demonstrated exacerbation of liver dysfunction due to immunosuppressive therapy and increased viral replication.

CONCLUSIONS

These results confirm those of our earlier study describing low replication ability of 8-bp deletion mutant HBV in vitro, and also indicate that the presence of genotype B correlates with reduced titer of HBV.

Reduced transcription and progeny virus production of hepatitis B virus containing an 8-bp deletion in basic core promoter

We have demonstrated previously the presence of an 8-bp deletion mutant, spanning from nt. 1768 to nt. 1775 in the basic core promoter region of hepatitis B virus (HBV) in patients with anti-HBe positive asymptomatic phase before developing acute exacerbation after immunosuppressive treatment. The transcription and progeny virus production activities of the mutant were examined by transfection of the recombinant plasmid [pUC Del(2)] containing the head-to-tail dimer DNA of the mutant into HepG2 cells. The amounts of hepatitis B surface antigen (HBsAg) and HBe antigens secreted into the culture medium were markedly reduced. Southern blotting of DNAs extracted from the culture medium also showed reduced mutant activity to produce progeny virus. Northern blotting and RNase protection assay of RNAs extracted from transfected cells demonstrated that the transcription of both precore mRNA and pregenome RNA was reduced significantly compared to that of wild-type HBV. The promoter activity examined by transfection of the CAT plasmid containing deletion mutant DNA was much lower than that of wild type. Co-transfection experiments, however, of the CAT plasmid containing wild-type DNA with pUC Del(2) reduced CAT activity induced by wild-type, suggesting that truncated X protein produced by the mutant does not possess a sufficient transactivating activity. Gel shift assay using HepG2 nuclear extract and a probe containing four TA-rich regions in CP and various competitors suggested that the lack of the third TA-rich region was responsible for the transcription reduction of precore mRNA and pregenome RNA. The possible mechanisms are discussed.

Reduced transcription and progeny virus production of hepatitis B virus containing an 8-bp deletion in basic core promoter

We have demonstrated previously the presence of an 8-bp deletion mutant, spanning from nt. 1768 to nt. 1775 in the basic core promoter region of hepatitis B virus (HBV) in patients with anti-HBe positive asymptomatic phase before developing acute exacerbation after immunosuppressive treatment. The transcription and progeny virus production activities of the mutant were examined by transfection of the recombinant plasmid [pUC Del(2)] containing the head-to-tail dimer DNA of the mutant into HepG2 cells. The amounts of hepatitis B surface antigen (HBsAg) and HBe antigens secreted into the culture medium were markedly reduced. Southern blotting of DNAs extracted from the culture medium also showed reduced mutant activity to produce progeny virus. Northern blotting and RNase protection assay of RNAs extracted from transfected cells demonstrated that the transcription of both precore mRNA and pregenome RNA was reduced significantly compared to that of wild-type HBV. The promoter activity examined by transfection of the CAT plasmid containing deletion mutant DNA was much lower than that of wild type. Co-transfection experiments, however, of the CAT plasmid containing wild-type DNA with pUC Del(2) reduced CAT activity induced by wild-type, suggesting that truncated X protein produced by the mutant does not possess a sufficient transactivating activity. Gel shift assay using HepG2 nuclear extract and a probe containing four TA-rich regions in CP and various competitors suggested that the lack of the third TA-rich region was responsible for the transcription reduction of precore mRNA and pregenome RNA. The possible mechanisms are discussed.

Therapeutic oral vaccination induces mucosal immune response sufficient to eliminate long-term Helicobacter pylori infection

We examined the efficacy of therapeutic oral vaccination using Helicobacter pylori-whole cell sonicate and cholera toxin (CT) in mice persistently infected with H. pylori. Efficacy was determined by bacterial culture and microscopic examination of gastric tissues for the persistence of bacteria at 6 weeks after the last vaccination. Vaccination of H. pylori-whole cell sonicate combined with CT eradicated bacteria in 10/16 mice (62.5%). Interestingly, oral vaccination with CT alone also eliminated the bacteria in 8/17 mice (47.1%). However, a therapeutic intraperitoneally administered vaccine failed to eradicate H. pylori from the stomach (1/17 mice, 5.9%). Identification of the type of immunity involved in the eradication process showed that oral vaccination enhanced the antigen-specific IgA in the feces and saliva. The efficacy of eradication of H. pylori correlated well with increases in IgA secretion in mucosal tissue and a higher labeling index of IgA-positive lumina of pyloric glands. Moreover, the expression of IL-4 mRNA in the stomach of mice with eradicated bacteria was higher than in the uneradicated group. Our results suggest that the efficacy of vaccination depends on the mucosal IgA response in the gastrointestinal tract against H. pylori via Th2 cell activation and that therapeutic oral vaccination induces a mucosal immune response sufficient to eradicate long-term infection with H. pylori.

Local secretory immunoglobulin A and postimmunization gastritis correlate with protection against Helicobacter pylori infection after oral vaccination of mice

C57BL/6 mice were orally immunized with five weekly doses of 2 mg, 200 microgram, or 2 microgram of Helicobacter pylori (Sydney strain) whole-cell sonicate combined with cholera toxin. One week after the last vaccination, mice were challenged with 5 x 10(7) CFU of live H. pylori three times at 2-day intervals. At 6 or 18 weeks after the challenge, mice were sacrificed and bacterial cultures and histological studies of the stomach were performed. Vaccination with 2 mg/session or 200 microgram/session inhibited H. pylori colonization by 90 and 100%, respectively. These mice were considered protected. Lower levels of H. pylori-specific immunoglobulin A (IgA) were detected in fecal and saliva samples before challenge. However, a significant increase in IgA secretion in mucosal tissue and a higher labeling index for IgA-positive lumina of pyloric glands were noted in these mice in response to challenge and in a vaccine dose-dependent manner. In protected mice, however, severe gastritis characterized by marked infiltration of inflammation mononuclear cells was noted at 6 weeks after challenge, compared with the gastritis seen in unprotected mice or nonvaccinated, ordinarily infected mice. Marked expression of gamma interferon mRNA was detected in the stomach of all protected mice, and 50% of these mice expressed interleukin 4 (IL-4) or IL-5 mRNA. Our findings suggest that local secretory IgA antibody and severe postimmunization gastritis correlate well with protection of mice against H. pylori infection.

Serological assessment of the early response to eradication therapy using an immunodominant outer membrane protein of Helicobacter pylori

Eradication of Helicobacter pylori infection cures gastritis and prevents recurrence of peptic ulcers. Endoscopy is usually used to evaluate the effectiveness of eradication therapy. We designed a new noninvasive assay system for the early evaluation of eradication of H. pylori infection in which a crude H. pylori outer membrane protein preparation (HPOmp) is used as an antigen, and we determined the sensitivity and specificity of the serological assay system. Immunoblot analysis showed that anti-HPOmp antibodies reacted to a protein with a molecular mass of approximately 29 kDa. In those patients who responded to therapy, the anti-HPOmp immunoglobulin G (IgG) titers measured by enzyme-linked immunosorbent assay (ELISA) at 1 month after the end of therapy were significantly lower than those before treatment (34.8% reduction; P < 0.001), and the posttreatment reduction in the antibody titer was significantly greater than that of the titer measured with a commercially available anti-H. pylori IgG ELISA (34.8% versus 16.1%; P < 0.001). When a 25% reduction of anti-HPOmp IgG titer at 1 month after the end of treatment was taken as the cutoff value for H. pylori eradication, the sensitivity and specificity of our new assay were 75% (51 of 68 treatment responders) and 96% (22 of 23 nonresponders), respectively. Our results indicate that the novel serological test with HPOmp might be a clinically useful tool for assessment of eradication of H. pylori.

Sequential analyses of the mutations in the core upstream and precore regions of hepatitis B virus genome in anti-HBe positive-carriers developing acute exacerbation

The nucleotide sequences of the core upstream and precore regions (371 nucleotide length, nt. 1604-1974) of hepatitis B virus (HBV) were analysed sequentially in three subjects who were positive serologically for anti-HBe and had acute clinical exacerbation after immunosuppressive treatment. These patients were asymptomatic HBV carriers before therapy. The results revealed that the mutant with an 8-bp deletion (nt. 1768-1775) located in the basic core promoter region was dominant in the asymptomatic HBV carrier phase in two of three subjects. After exacerbation, however, such mutant clones possessing 8-bp deletion disappeared or decreased in number and were replaced by the clones possessing a precore stop codon mutation G to A (nt. 1896) or by the clones possessing additional contiguous point mutations A to T (nt. 1762) and G to A (nt. 1764) and a new point mutation C to T (nt. 1653). Possible relationships between acute exacerbation of liver function accompanied by mutation and the transition of the dominant clones were discussed.

Sequential analyses of the mutations in the core upstream and precore regions of hepatitis B virus genome in anti-HBe positive-carriers developing acute exacerbation

The nucleotide sequences of the core upstream and precore regions (371 nucleotide length, nt. 1604-1974) of hepatitis B virus (HBV) were analysed sequentially in three subjects who were positive serologically for anti-HBe and had acute clinical exacerbation after immunosuppressive treatment. These patients were asymptomatic HBV carriers before therapy. The results revealed that the mutant with an 8-bp deletion (nt. 1768-1775) located in the basic core promoter region was dominant in the asymptomatic HBV carrier phase in two of three subjects. After exacerbation, however, such mutant clones possessing 8-bp deletion disappeared or decreased in number and were replaced by the clones possessing a precore stop codon mutation G to A (nt. 1896) or by the clones possessing additional contiguous point mutations A to T (nt. 1762) and G to A (nt. 1764) and a new point mutation C to T (nt. 1653). Possible relationships between acute exacerbation of liver function accompanied by mutation and the transition of the dominant clones were discussed.

Genotyping of hepatitis C virus in the Dominican Republic

Genotyping of hepatitis C virus (HCV) of liver disease patients in the Dominican Republic was performed. Eighty-four samples positive for HCV antibody, which were confirmed by ELISA, particle agglutination, and recombinant immunoblot assay III tests, were subjected to HCV genotyping by polymerase chain reaction using type-specific primers located in the nonstructural protein 5 region. Of the 84 samples tested, 50 (59%) were found to have genotype 1a/I and this genotype was the most frequent type detected in the present study. The numbers of isolates of genotypes 1b/II, 2a/III, 2b/IV, and 3a/V were three (3.6%) six (7.1%), two (2.4%), and two 2.4%), respectively. The number of samples having mixed genotype populations was 16 (19%). The possible causes of the high prevalence of genotype 1a/I in the Dominican Republic compared with other countries and of the high detection ratio of samples having mixed genotypes are discussed.

Rabies virus M protein expressed in Escherichia coli and its regulatory role in virion-associated transcriptase activity

Rabies virus M protein was expressed in Escherichia coli in the form of a fusion protein with maltose binding protein (MBP) and purified by amylose affinity column chromatography after extraction. In order to investigate the possible regulatory role of M protein in viral transcription, an assay system for rabies virion-associated transcriptase activity was established by using the ribonucleoprotein (RNP) cores prepared from purified virions. Analysis of the products of the transcription assay system showed that the products are sensitive to RNase and are positive-strand RNA. Addition of the fusion protein to the system after cleavage with a proteinase Factor Xa (FXa), which cleaves the fusion protein into the M protein and MBP, resulted in an efficient and dose-dependent inhibition of the transcription. Furthermore, addition to the system of anti-M protein monoclonal antibody significantly restored the transcription. Control experiments with the same transcription assaying system using rabies virus nucleoprotein expressed as a fusion protein with MBP and cleaved with FXa did not result in an inhibition of the transcription. These results suggest that the M protein of rabies virus has the property to down-regulate virion-associated transcription.

Rapid desensitization of serotonin 5-HT2C receptor-stimulated intracellular calcium mobilization in CHO cells transfected with cloned human 5-HT2C receptors

Serotonin 5-HT2C receptor-mediated intracellular Ca2+ mobilization was investigated in Chinese hamster ovary (CHO) cells transfected with 5-HT2C receptors. Fura-2 acetoxymethyl ester was used to investigate the regulation of 5-HT2C receptor function. CHO cells, transfected with a cDNA clone for the 5-HT2C receptor, expressed 287 fmol/mg of the receptor protein as determined by mianserin-sensitive [3H]mesulergine binding (KD = 0.49 nM). The addition of 5-HT mobilized intracellular Ca2+ in a dose-dependent fashion, ranging from a basal level of 99 +/- 1.8 up to 379 +/- 18 nM, with an EC50 value for 5-HT of 0.029 microM. Exposure to 5-HT, 1-(3-chlorophenyl)piperazine dihydrochloride (a 5-HT2C agonist), and 1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane (a 5-HT2C and 5-HT2A agonist) resulted in increased intracellular Ca2+ levels. Mianserin, mesulergine, ritanserin, and ketanserin each blocked 5-HT-mediated intracellular Ca2+ mobilization more effectively than spiperone. The receptor was rapidly desensitized by preexposure to 5-HT in a time- and concentration-dependent manner. Mezerein and phorbol 12-myristate 13-acetate, protein kinase C activators, weakly inhibited the intracellular Ca2+ mobilization induced by 10 microM 5-HT. Furthermore, the protein kinase C inhibitor H-7 partially prevented the protein kinase C activator-induced inhibition of the 5-HT-mediated increase in intracellular Ca2+ concentration. The desensitization induced by pretreatment with 5-HT was blocked by W-7, added in conjunction with 5-HT, and partially inhibited by W-5, a nonselective inhibitor of protein kinases and weak analogue of W-7.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutations in the core promoter/enhancer II regions of naturally occurring hepatitis B virus variants and analysis of the effects on transcription activities

The regulatory regions for transcription and replication of several hepatitis B virus (HBV) genomes from 19 patients having various forms of HBV infection were sequenced. Predominant mutations were found to occur naturally in nucleotide positions 1762 (A to T) and 1764 (G to A) in chronic hepatitis patients and in asymptomatic carriers after seroconversion, but were not observed in HBeAg-positive healthy carriers. Since these positions were located in the basic core promoter and the overlapping enhancer II regions situated within the core upstream region, transcriptional activity was examined by chloramphenicol acetyltransferase assay to determine if there was a possible difference between the mutant and wild-type HBV. However, no significant difference was detected upon comparison of the promoter and enhancer activities between mutant and wild-type HBV.

Inhibitory effect of transferrin on progesterone production in the granulosa cell of humans in vivo and porcine granulosa cell in vitro

We evaluated the effect of transferrin on the regulation of granulosa cell function in humans by evaluating the production of progesterone (P) in the preovulatory phase in vivo, and in cultured porcine granulosa cells in vitro. Twenty-five women treated for in vitro fertilization and embryo transfer had their serum levels of 17 beta-estradiol (E2) and P determined on the day of administration of human chorionic gonadotropin. Transferrin concentrations were also determined in ovarian follicular fluid. In an in vitro study, porcine granulosa cells were cultured in the presence of follicle-stimulating hormone (FSH) and transferrin. Serum levels of P showed a significant negative correlation with those of transferrin (r = -0.53, p < 0.01), whereas serum levels of E2 did not (r = 0.14). When the subjects were divided into two groups by serum P concentration (low P < 1 ng/ml, high P > or = 1 ng/ml) serum concentrations of transferrin were significantly increased in the group with the low versus the high level of p (p < 0.01). Production of P by porcine granulosa cells was suppressed by transferrin in the presence of various concentrations of FSH. Increasing the dose of transferrin significantly suppressed the production of P by those cells in a dose-dependent fashion. The production of P during the preovulatory phase may be suppressed by transferrin in the granulosa cells.

Target cells of cytotoxic T lymphocytes directed to the individual structural proteins of rabies virus

Target cells of cytotoxic T lymphocytes (CTL) directed to the individual structural proteins (except for the large polymerase (L) protein) of rabies virus were established by expressing only the respective protein in murine neuroblastoma (NA) and murine macrophage (J774-1) cell lines. Mice infected with the ERA strain of rabies virus developed CTL responses to all of these rabies virus proteins. The cytotoxic activity was abrogated by pretreatment of the effector cells with anti-CD8 monoclonal antibody (MAb) and complement but not with anti-CD4 MAb. Cell lysis by CTL was blocked in the presence of anti-major histocompatibility complex (MHC) class 1 antibodies in J774-1 cell lines. Rabies virus-infected cells express these proteins at the surface, which can be recognized and lysed by the respective CTL. Mice immunized with beta-propiolactone-inactivated virus induced a CTL response against glycoprotein but not against internal viral components. This assay system might be useful for further analysis of the possible contribution of these proteins in the cell-mediated immune protection against rabies.

Analysis of upstream region of hepatitis B virus core gene using in vitro transcription system

Transcription of the core (C) gene of hepatitis B virus DNA (HBV-DNA) was studied by an in vitro transcription system using nuclear extracts of human liver cell (HepG2) and non-liver cell (HeLa) origins. RNA polymerase II-dependent run-off transcription of 3.5-kb (C) mRNA was observed in both nuclear extracts; but the efficiency was much higher in the HepG2 nuclear extract. Analysis of run-off transcripts using upstream deletion mutants of HBV-DNA demonstrated that there are two transcription start sites located at approximately nucleotide numbers (nt) 1,797 +/- 5 and 1,815 +/- 5. This analysis also suggested that the minimum core promoter sequence and a cis-acting and liver-specific element for C mRNA transcription are located in the downstream region from -80 and -110 (HincII site) of transcription start sites, respectively. DNA-binding protein assays using synthetic double-stranded oligonucleotide probes corresponding to three regions in the upstream region (nt from 1,401 to 1,760) of transcription start sites revealed that there are some liver cell-specific and non-specific DNA-binding proteins in both nuclear extracts. The amount of those proteins was generally higher in the HepG2 nuclear extract. However, no obvious correlation was observed in the present study between the presence of DNA-binding proteins and transcription activity of nuclear extracts in our system. The possible causes of this discrepancy are discussed.

Protective efficacy in mice of post-exposure vaccination with vaccinia virus recombinant expressing either rabies virus glycoprotein or nucleoprotein

Mice vaccinated intraperitoneally (i.p.) with 10(7) p.f.u. of a vaccinia virus recombinant expressing either the glycoprotein (rVac-G) or nucleoprotein (rVac-N) of rabies virus 3 weeks before challenge were protected against peripheral lethal infection. Similarly, by post-exposure vaccination in which mice were first infected with rabies virus and subsequently vaccinated i.p. with the recombinant, rVac-G conferred protection when given immediately following infection and up to 24 h after infection. Prior treatment of those mice with anti-CD8 monoclonal antibodies (MAb) did not significantly affect the outcome of the infection. In contrast, rVac-N failed to confer protection even with higher doses (10(8) p.f.u.) of the virus or even when administered by the intradermal route. Anti-nucleoprotein antibody production by these mice was not suppressed by prior rabies virus infection and the levels and the time of antibody production were similar to those of anti-glycoprotein antibody production in mice vaccinated with rVac-G after rabies virus infection. The cytotoxic T lymphocyte response was also not down-regulated by rabies virus in the mice that were given rVac-N. Possible mechanism(s) for the ineffectiveness of rVac-N by post-exposure vaccination in contrast to pre-exposure vaccination was discussed.

A unique mutation of glycoprotein gene of the attenuated RC-HL strain of rabies virus, a seed virus used for production of animal vaccine in Japan

Although the RC-HL strain of rabies virus is avirulent in adult mice, the amino acid at position 333 of its G protein is arginine, which is thought to be necessary for virulence in adult mice upon intracerebral inoculation of the virus. This result suggests that besides arginine at position 333, some other positions of G protein might also be involved in determining the virulence of rabies virus.

Nucleotide sequence of the nucleoprotein gene of the RC.HL strain of rabies virus, a seed strain used for animal vaccine production in Japan

By using a phage vector (lambda ZAP II) and the mRNA extracted from IMR-32 cells infected with the RC.HL strain of rabies virus, we constructed a cDNA library from which four nucleoprotein (N)-specific cDNA clones were obtained by Southern blot hybridization. These clones contained a cDNA insert of about 1.4 kb, in which the longest open reading frame was the same length as that reported for the N cDNA of three fixed strains, CVS, PV, and SAD B19. When the nucleotide and deduced amino acid sequences were compared between the RC.HL and the three strains, homology was within the range of 91.5-91.8% and 95.1-96.0%, respectively. Of 183 nucleotides of the RC.HL N-cDNA that were not identical to that of the corresponding site of at least one of the three strains, 41 were shared with the CVS strain, whereas only three were shared with either of the other two strains. In the amino acid sequence, we found 29 residues that were not shared in common with all of the four strains, 11 of which were the substitutions with radically different amino acids that might cause conformational changes of the protein, and, in addition, five of which were located in the region close to the C terminus. The number of such amino acid substitutions between the RC,HL and CVS strains was smaller than that of the other three strains. These results are not inconsistent with the presumption that the RC.HL and CVS strains originated from the same laboratory strain of the Pasteur viruses.

Circadian variation in amikacin clearance and its effects on efficacy and toxicity in mice with and without immunosuppression

A once-daily dosage regimen has been recently recommended in the use of aminoglycoside antibiotics since they induce a postantibiotic effect. In choosing this regimen, one must determine the most appropriate time of day for administration of the drug. We investigated the effects of the timing of amikacin (AMK) administration on the kinetics, the efficacy against intraperitoneal infection with Pseudomonas aeruginosa, and the toxicity of AMK in mice with and without immunosuppression. We found circadian variations in the kinetics, efficacy, and toxicity of the drug in mice. Male and female ICR mice, which were housed under a light-dark (12:12 h) cycle with free food and water intake, were injected subcutaneously with AMK sulfate 50 mg/kg body wt. There was a circadian variation in AMK clearance for both sexes with the maximum value in the dark phase and the minimum in the light phase after a single administration. When AMK 500 mg/kg/day was repeatedly administered once daily for 30 days, higher toxicity was demonstrated in mice injected with the drug at the time of day with lower AMK clearance, although no difference was demonstrated in the toxicity between the two time points with different AMK clearance when AMK 1,500 mg/kg was administered in a single dose. The ED50 of AMK to cure the infected mice in the midlight phase (13:00 h) with lower clearance was significantly lower than that in the middark phase (01:00 h) with higher clearance. In contrast, the ED50 in the early light phase (09:00 h) was significantly lower than that in the early dark phase (21:00 h), although AMK clearance was no different between these two different time points. In mice premedicated with cyclophosphamide to suppress immune functions, the difference in the ED50 of AMK was still demonstrated between 13:00 and 01:00 h, but not between 09:00 and 21:00 h. The present study shows not only that there were circadian variations in both AMK clearance and toxicity after repeated administration, but also that there was a circadian variation in the efficacy of AMK in mice infected with P. aeruginosa. These results suggest that the timing of drug administration should be considered in pharmacotherapy with AMK and that the most appropriate time of administration in mice and nocturnal animals may be in the midlight (resting) phase. They also suggest that the ED50 of AMK against P. aeruginosa infection may be influenced not only by the circadian variation in pharmacokinetics but also by the variations in immune systems suppressed by cyclophosphamide.

Correlation of serum antibody titers against hepatitis C virus core protein with clinical features by western blot (immunoblot) analysis using a recombinant vaccinia virus expression system

In order to study the relationships among the clinical features of hepatitis C patients, the presence of hepatitis C virus (HCV) RNA in their blood, and their serum antibody titers against the core protein of virus and to study the antibody levels in asymptomatic HCV carriers, a recombinant vaccinia virus containing a core protein gene was constructed. The recombinant virus expressed a protein with a molecular mass of 22 kDa in RK-13 cells as determined by Western blot (immunoblot) analysis. By using the cell lysate of virus-infected cells and serially diluted serum samples, core antibody titers in the groups of patients in the chronic hepatitis phase and in the convalescent phase as well as in asymptomatic carriers were determined by enhanced chemiluminescence Western blot analysis. Almost all patients in the chronic phase were shown to have high antibody titers of more than 1:500,000 and with no exception had of HCV RNA in their sera. On the other hand, patients who had recovered naturally and were in the convalescent phase were shown to have significantly lower antibody titers, and the antibody was not detected in the lowest serum dilution of 1:500 in 43% of these patients (three of seven total patients). Antibody levels of patients who showed a good response to interferon treatment decreased to intermediate levels between those of patients in the chronic phase and those of patients in convalescent phase. The antibody titers in asymptomatic carriers varied considerably from 1:500,000 to 1:500, and 41% (11 of 27 total individuals) of these carriers showed a high titer equivalent to that of those in the chronic phase. Core antibody was detected consistently in the individuals in whom HCV RNA was detected. This system for core antibody might be useful for identifying the stage of an apparent HCV infection.

Resistance of mice vaccinated with rabies virus internal structural proteins to lethal infection

Mice were vaccinated with recombinant vaccinia virus (rVac) expressing the glycoprotein (G), nucleoprotein (N), phosphoprotein (NS) or matrix protein (M) of rabies virus and their resistance to peripheral lethal infection with street rabies virus was examined. Mice vaccinated with rVac-G or rVac-N developed strong antibody responses to the corresponding proteins and essentially all mice survived challenge infection. Mice vaccinated with rVac-NS or rVac-M developed only a slight antibody response, however, a significant protection (59%) was observed in the rVac-NS-vaccinated mice, whereas rVac-M-vaccinated mice were not protected. No anti-G antibodies were detected in the sera of mice which has been vaccinated with rVac-N or rVac-NS and survived challenge infection. Passive transfer of anti-N monoclonal antibodies (MAbs) recognizing an epitope located on amino acids 1-224 of the protein prior to challenge resulted in significant protection, although the protection was not complete even with a high amount of antibodies. In contrast, none of the mice given MAbs recognizing an epitope of amino acids 247-415 or F(ab')2 fragments from a protective MAb IgG were protected. Administration of anti-CD 8 MAb to rVac-N-vaccinated mice showed no significant effect on protection. Our observations suggest that a considerable part of the protection achieved by the vaccination with rVac-N can be ascribed to the intact anti-N antibodies recognizing an epitope located on amino acids 1-224 of the protein.

Comparative sequence analysis of the M gene among rabies virus strains and its expression by recombinant vaccinia virus

Nucleotide sequences and the deduced amino acid sequences of the gene encoding the matrix (M) protein of the Nishigahara and the CVS strains of rabies virus have been determined. The M gene is 609 nucleotides long and is capable of coding for a peptide composed of 202 amino acids. Sequence comparison of these M genes with those of other stains [Pasteur (PV), ERA, Avol] revealed that there is 89.7-91.5% homology at the nucleotide level, and 90.1-92.1% homology at amino acid level, between almost all combinations of these strains. However, in the combinations of the PV and ERA strains, and the virulent CVS and the avirulent CVS-derived Avol strains, much higher homology was observed both at the nucleotide and amino acid levels. The predicted secondary structure and hydropathy profiles also exhibited similar features. Recombinant vaccinia virus containing the M gene was constructed. Sodium dodecyl sulfate (NaDodSO4)-polyacrylamide gel electrophoresis of the precipitates obtained by immune reaction of the recombinant virus-infected cell lysate with a monoclonal antibody against the M protein revealed that electrophoretic mobility of the expressed protein is indistinguishable from that of the authentic M protein from rabies virions.

Suppression of cell-mediated immunity by street rabies virus infection

An attempt to define a severe suppression of cell-mediated immunity by street rabies virus infection was undertaken by using the mice lethally and peripherally infected with a street rabies virus (1088 strain). The cell-mediated cytotoxic (CMC) activity of the spleen cells from those mice once slightly increased until day 4 after infection but declined rapidly thereafter until their death on days 10 to 12 after infection. In parallel with a decrease of CMC response of the spleen cells from 1088-infected mice, proliferative response to Con A, IL-2 activity in the culture supernatants of Con A-induced proliferation, responsiveness to exogenously added IL-2 and to Con A to express IL-2R, of those cells became suppressed, and the marked decrease of the total number of spleen cells was observed. Selective depletion of CD4+ and CD8+ cells in the spleens, abnormalities of IL-1 and E-type prostaglandins (PGE2) production or production of inhibitory component able to block IL-2 activity by spleen cells were not observed and these factors did not appear to be associated with the suppression of proliferative response to Con A. However, an apparent association of CD8+ cells in the suppression of differentiation of pre-cytotoxic lymphocytes (CTL) into CTL was demonstrated in the co-culture experiments of the spleen cells from 1088-infected mice with spleen cells of mice infected with an attenuated rabies virus (ERA strain) which can induce higher levels of CMC response. There was no evidence of the productive replication of rabies virus in thymus and spleen of 1088-infected mice. The relationship of these observations to current theories on virus-induced immunosuppression was discussed.

Mapping of the antigenic determinants recognized by monoclonal antibodies against the M2 protein of rabies virus

Twenty-one hybridomas producing monoclonal antibodies (moAbs) against the M2 protein of the Nishigahara (RECH) strain of rabies virus were prepared using the SDS-polyacrylamide gel-purified M2 protein as the immunogen. All moAbs reacted with the protein after Western blotting of rabies virus. By combinations of competitive binding assays, examination of the reactivity of moAbs to the cells infected with parent RCEH and two other strains, CVS and HEP-Flury, and immunoprecipitation with in vitro translation products derived from full-length and truncated cDNAs of the M2 gene, these moAbs could be classified into seven epitope groups. Of these, 20 moAbs belonging to six epitope groups were suggested to recognize an antigenic determinant in the amino-terminal region, from the 1st to the 72nd amino acid of the protein (8 moAbs from two groups directed to amino acids 1 to 72; 2 moAbs from a group directed to amino acids 9 to 72; 5 moAbs from a group directed to amino acids 17-72; 5 moAbs from two groups directed to amino acids 32 to 72). The antigenic determinant recognized by the remaining 1 moAb was shown to be located in the amino acid region from 50 to 171. These moAbs should be useful for further studies on the biological functions of the M2 protein of rabies virus.

Comparison of rabies virus G proteins produced by cDNA-transfected animal cells that display either inducible or constitutive expression of the gene

By using a retrovirus expression vector, pZIP-NeoSV(X)1, we introduced a cloned cDNA of the rabies virus G gene into BHK-21 cells and the NA cell clone originated from the murine neuroblastoma C1300 line. Using the neomycin resistance gene of the vector, we isolated several G418-resistant transformants of BHK-21 and NA cells (referred to as G-BHK and G-NA cells, respectively). G-BHK cells constitutively produced G proteins, whereas G-NA cells produced the proteins only when treated with sodium butyrate. G proteins synthesized in these transformants were transported normally to the surface of the cell, but they displayed different electrophoretic mobilities, which were shown to originate from differences in the number and structure of the carbohydrate moieties of the protein; G-BHK cells produced highly glycosylated and sialylated G proteins, whereas less glycosylated and much less sialylated G proteins were produced by G-NA cells as observed in virus-infected NA and BHK-21 cells, indicating that the glycosylation and sialylation of the G protein depend on the cellular conditions under which the protein was produced. In the absence of sodium butyrate the G protein was not detectable in G-NA cells either by immunoblot assay or fluorescent antibody staining, but the cells were fairly sensitive to syngeneic rabies virus-specific cytotoxic T lymphocytes, although the sensitivity was much increased by treatment with sodium butyrate.

Conserved nucleotide sequence of rabies virus cDNA encoding the nucleoprotein

The cDNAs of rabies virus (the CVS strain) encoding the structural proteins (G, N, NS, and M) were cloned. Of these clones, the nucleotide sequence of the cDNA encoding the nucleoprotein was determined to compare with those of other strains of rabies virus. The comparison confirmed that the nucleotide sequences and deduced amino acid sequences are highly conserved among strains including an avirulent strain.

Effects of monensin on subcellular structure, thyroglobulin secretion and peroxidase activity of cultured thyroid cells obtained from patients with hyperthyroidism

The effects of monensin on subcellular structure, release of thyroglobulin (TG) and peroxidase (PO) activity were investigated using primary cultures of thyroid cells obtained from patients with Basedow's disease (Basedow's cells). TG concentration in the culture medium was measured by a sandwich enzyme immunoassay and the amount of TG in cultured cells was measured with an identical sandwich enzyme immunoassay after lysis of the cells with Triton X-100. PO activity of cultured cells was measured by a biochemical method. Addition of TSH (10 mU/ml/day) to the culture medium increased the synthesis and release of TG. When monensin (1 micron/l) was added to the medium on the last day of a 3-day incubation with TSH, the Golgi complex showed vacuolative change ultrastructurally, and the amount of intracellular TG was increased, whereas the amount of TG in the culture medium and PO activity became lower than those in the control group. These results suggest that in cultured Basedow's cells, TG is secreted through the Golgi complex, and that the activity of PO is elevated after processing in the Golgi complex.

Protection against rabies in mice by a cytotoxic T cell clone recognizing the glycoprotein of rabies virus

By the use of liposomes containing the purified surface glycoprotein (G) of rabies virus and the haemagglutinin-neuraminidase (HN) and fusion (F) glycoproteins of Sendai virus, the target antigen of anti-rabies virus cytotoxic T lymphocyte (CTL) clones isolated in a previous study was identified as the G protein. Recognition of the H-2K determinant of the class I major histocompatibility complex (MHC) was necessary for target lysis by the CTL clones. One of the CTL clones was examined for the ability to protect mice against a lethal rabies virus infection. CTL were transferred into syngeneic mice which had been infected in the hind footpad with the ERA strain of rabies virus. The infection was converted into a lethal infection by cyclophosphamide treatment 1 day after virus infection. Transfer of CTL 2 to 3 days after virus infection protected approximately 50% of mice during the observation period of 4 weeks. Greater protection was obtained in mice receiving both anti-rabies virus antibodies and CTL cells.

Induction of peroxidase and thyroglobulin by TSH in cultured thyroid cells from patients with Basedow's disease and its inhibition by actinomycin D

The effects of TSH on peroxidase activity (PO) and thyroglobulin (TG) production were investigated using primary cultures of thyroid cells obtained from patients with Basedow's disease (Basedow's cells). PO activity of cultured cells and TG concentration in the culture medium were measured by biochemical and sandwich enzyme immunoassays, respectively. The addition of TSH (10 mU/ml/day) to the medium did not increase the cell number but did increase the PO activity and TG concentration. It took more than 3 days for the PO activity of cells cultured with TSH (stimulated group) to reach a level twice that of cells cultured without TSH (control group), whereas 2 days of incubation with TSH was sufficient for increasing the TG concentration. When actinomycin D (AD) was added to the medium on the first day of 3-day incubation with TSH, the stimulatory effect of TSH on PO was completely blocked and the TG concentration was reduced to half that of the control group. AD given to the stimulated group on the last day of induction produced no inhibitory effect on the induction of PO activity by TSH, but reduced the TG concentration to almost half that in the stimulated group. An electron microscopic study of Basedow's cells cultured with AD and TSH failed to reveal any cytopathic change. The findings of the present study suggested that in cultured Basedow's cells TSH induces PO activity and TG production through the synthesis of new messenger RNA.

Tris inhibits both proteolytic and oligosaccharide processing occurring in the Golgi complex in primary cultured rat hepatocytes

Tris caused the distention of the Golgi cisternae in primary cultured rat hepatocytes and perturbed the functions occurring there. Proteolytic cleavage of precursors of both albumin and complement C3 was inhibited, whereas that of prohaptoglobin was not affected by Tris. These effects on the proteolytic cleavages resemble those of acidotropic amines (Oda, K., and Ikehara, Y. (1985) Eur. J. Biochem. 152, 605-609; Oda, K., Koriyama, Y., Yamada, E., and Ikehara, Y. (1986) Biochem. J. 240, 739-745). However, the effects of Tris significantly differed from acidotropic amines on the basis of its effects on the processing of N-linked oligosaccharides of glycoproteins. Both alpha 1-protease inhibitor and haptoglobin secreted from the Tris-treated cells were found to contain almost equal amounts of endo-beta-N-acetylglucosaminidase H-sensitive and -resistant oligosaccharides, whereas the glycoproteins from both the control and methylamine-treated cells were resistant to the enzyme. The endo-beta-N-acetylglucosaminidase-sensitive oligosaccharides were analyzed to be Man8-5GlcNAc by high resolution gel permeation chromatography, suggesting that trimming of alpha-mannose residues from the precursor Man9GlcNAc2 is incomplete in the Tris-treated cells. On the other hand, Tris did not significantly inhibit incorporation of radioactive monosaccharides (N-acetylglucosamine, galactose, and fucose) into the glycoproteins. However, two-dimensional gel electrophoresis in combination with neuraminidase digestion demonstrated that sialylation was markedly inhibited by Tris. Taken together, our results reveal that Tris inhibits not only the sialic acid addition which takes place in the trans Golgi region, but also the trimming step of high mannose-type oligosaccharides, which is thought to occur before glycoproteins reach the trans Golgi region.

Endogenous peroxidase activity in primary culture of human thyroid cells. Localization and measurement

Intracellular localization of and an assay method for endogenous peroxidase (PO) activity were studied using primary culture of thyroid cells obtained from patients with hyperthyroidism. PO activity was visualized by cytochemical reaction and was located mainly in perinuclear cisternae and rough endoplasmic reticulum. With increased culture time, the number of cells showing positive PO activity and amount of the enzyme reaction product in individual cells showed a parallel decrease. For measurement of PO activity, cultured thyroid cells were frozen and thawed and then incubated with citric acid buffer solution containing o-phenylenediamine (opd) and hydrogen peroxide. After incubation, the optical density (OD) of the solution colorized by endogenous peroxidase was measured at 405 nm using a microplate reader. About 1 X 10(4) cells were sufficient for assay of PO activity. Using the above method to assay PO activity and sandwich enzyme immunoassay for thyroglobulin (TG), chronological changes in the PO activity and TG concentration in the culture medium were examined. Although the cells showed no decrease in number, PO activity and TG concentration decreased chronologically. When the ratio of PO activity to TG concentration was calculated, in 3 cases the ratio was almost constant, and in the remaining two, it decreased chronologically. The present biochemical method thus seems useful for determining peroxidase activity of cultured thyroid en masse.

Microneutralization test for rabies virus based on an enzyme immunoassay

We have developed an enzyme immunoassay for rabies virus by using acetone-fixed infected cell cultures as the antigen. This test was used to demonstrate virus-neutralizing antibodies in human and animal sera and was as sensitive as and easier to perform than the rapid fluorescent-focus inhibition technique.

Characterization of the measles virus isolated from the brain of a patient with immunosuppressive measles encephalitis

Two strains of measles virus with different biologic properties were isolated from the brain of a patient with immunosuppressive measles encephalitis. One strain (Oita-1) grew extremely slowly in Vero cells and did not produce any cell-free virions. The other strain (Oita-2) replicated well, and a small amount of cell-free virus was detected from the culture medium and the freeze-thawed homogenate. Neurovirulence of the Oita-1 strain to mice was, however, stronger than that of the Oita-2 strain. Synthesis of the M protein by the Oita-2 strain was not demonstrable in the infected cells when they were labeled for 24 hr; however, a new protein moiety that was smaller in molecular weight than the M protein and that was not precipitated with monoclonal antibody to M protein was demonstrated by pulse-labeling for 1 hr. Antibodies to the M protein, as well as to other proteins, were detected (by immunoprecipitation) in the serum and cerebrospinal fluid of the patient.

Enhanced antibody responses in mice by combined administration of interferon with rabies vaccine

Exogenous interferon administered to mice at the time of, and 6 hours after the first dose of 3 daily vaccinations accelerated and enhanced the IgM and IgG antibody responses to rabies virus. The effect of interferon was not evident when the interferon was administered later in the vaccination schedules and was abrogated by prior administration of anti-interferon antibody to the mice. The number of IgM antibody secreting cells in the spleen was significantly greater in mice treated with interferon than in controls.

Murine T cell clones directed to rabies virus: isolation and some of their properties

Seventeen Thy-1+ cell clones were induced in A/J mice immunized with the HEP-Flury strain of rabies virus after repeated stimulations with antigens in vitro. Ten clones with cell surface phenotypes Thy-1+, Lyt-1-,2+ were cytotoxic T lymphocytes (CTL) which lysed the virus-infected target cells under H-2 restriction. Target cells expressed the G and M2 structural proteins of rabies virus on their surface; however, target lysis by CTL clones was not blocked by anti-rabies antibody or by monoclonal antibodies to these proteins. All of the CTL clones efficiently and equally lysed target cells infected with three different strains of rabies virus and were cross-reactive for target cells infected with one (Duvenhage virus) of three different rabies serogroup viruses. Another five clones having phenotype Thy-1+, Lyt-1+,2- did not show any cytotoxic activity. The proliferation response of these clones to antigen stimulation was virus-specific and H-2-restricted. These clones were able to grow in culture medium without any or with the addition of low concentrations of T cell growth factor, in contrast to CTL clones, and were considered to be helper T lymphocytes (HTL). Both CTL and HTL clones produced gamma-interferon in response to antigen stimulation. The remaining two clones were Thy-1+, Lyt-1-,2-, asialo-GM1+, and were not cytotoxic to target cells even in the presence of anti-rabies antibody but were cytotoxic to YAC-1 cells. Further studies with these clones should allow us to investigate more closely the role of T cells in the pathogenesis of rabies.

[Immunosuppressive factor(s) present in crude preparations of human chorionic gonadotropin]

The present study was undertaken to purify and characterize the immunosuppressive factor(s) present in commercially available crude human chorionic gonadotropin (crude hCG). Amberlite CG-50 column chromatography of crude hCG(2,680 IU/mg) produced hCG(7,130 IU/mg) and non hCG(130 IU/mg) fractions. The hCG fraction was further fractionated by Sephadex G-100 column chromatography and a highly purified fraction with a potency of 18,600 IU/mg was obtained. The non hCG fraction was separated into two fractions, F-1 and F-2, on Sephadex G-75. Each fraction was examined for its inhibitory effect on the incorporation of 3H-thymidine by normal human peripheral blood mononuclear cells stimulated with phytohemagglutinin (PHA test) or mixed lymphocyte reaction (MLR test). The original crude hCG showed considerable inhibition in both PHA and MLR tests, but the purified hCG showed no inhibition. F-1 fraction, having a molecular weight (M.W.) ranging from 75,000 to 100,000 daltons, was the most potent in the inhibition of all the other fractions. The inhibitory activity in the F-1 fraction was dose-dependent and relatively stable when exposed to heat and trypsin treatment, but completely inactivated by neuraminidase treatment. These results strongly suggest that the macromolecular substance(s), with a M.W. of 75,000 to 100,000, which is present in crude hCG but different from genuine hCG, has potent immunosuppressive effects and that sialic acid residues in the substance(s) are related to the manifestation of these effects.

Protective effect of measles virus inoculation on subacute sclerosing panencephalitis virus-infected mice

The Biken strain of subacute sclerosing panencephalitis (SSPE) virus caused a fatal neurologic disease in adult mice after intracerebral inoculation. However, the mice were completely protected from the disease when a high dose of measles virus was given intracerebrally after the SSPE virus infection. The measles virus inoculation induced interferon production and immune responses. An experiment with athymic nude mice showed that interferon and anti-measles antibody were able to prolong the incubation period of the disease but not to protect the SSPE virus-infected nude mice from death. For complete protection, T lymphocytes appeared to be essential. The present study suggested that the protective effect of measles virus inoculation is basically due to the induction of immune responses and that SSPE virus infection in mice is susceptible to immune reactions.

Auditory brain stem responses in relation to the clinical symptoms of schizophrenia

Auditory brain stem responses (ABSR) were examined systematically both in normal and schizophrenic subjects. All ABSR wave forms were evoked by click stimuli, which were delivered binaurally through headphones both to normal subjects and to a nondeteriorated group of schizophrenics. However, in the group of schizophrenics with marked deterioration of personality, not all wave forms were elicited, and the amplitudes were low. The characteristics of the ABSR wave forms correlated well with the clinical symptoms of the schizophrenic illness. The cause of these ABSR wave form changes in schizophrenics is discussed.

Further studies on an improved haemagglutination inhibition test with higher sensitivity for rabies virus antibody

The efficiency of the removal of non-specific inhibitors of rabies virus haemagglutinin by treatment with colloidal silicic acid, which was proposed in an earlier study, was examined in a number of test samples. The non-specific inhibitors were removed in 289 out of 296 normal human sera (97.6%) by this treatment to a level that was undetectable at the 1:4 starting dilution in the haemagglutination inhibition test. Antigenic differences among three strains of rabies virus were detected in the haemagglutination inhibition test and the antibody titres to the homologous antigens were apparently higher than those to heterologous antigens.

Effect of monensin on the synthesis, maturation and secretion of vesicular stomatitis virus proteins in a monensin-resistant Chinese hamster ovary cell line

We compared the effects of the cationic ionophore, monensin, on the synthesis, maturation and release of vesicular stomatitis virus (VSV) in cultures of Chinese hamster ovary (CHO) cells and the monensin-resistant clone, MonR-31. Our results depended on the dose and time of the addition of monensin to the infected cells, from 1 h prior to VSV infection to 1 h after infection. VSV production was more resistant in MonR-31 than in CHO cells when the ionophore was added 1 h prior to VSV infection. Monensin added 1 h after VSV infection showed the opposite phenomenon; release of virus particles into the medium was 10- to 10(5)-fold less in MonR-31 cells than in CHO cells, and the intracellular virus number in the resistant cells was one-third to one-fourth of that in the parental CHO cells. Syntheses of all virus-associated G, N and M proteins were inhibited in both cell lines by monensin, but especially so in the MonR-31 cells. There were no marked qualitative changes in the biochemical properties of viral glycoprotein G in virus-infected CHO and MonR-31 cells treated with monensin after virus infection. An endoglycosidase H-resistant G with a molecular weight smaller than that of normal G and attachments of palmitate or fucose on the truncated G protein appeared. Alteration of the secretion of as well as the synthesis of the enveloped virus is discussed in relation to the monensin susceptibility of the resistant MonR-31 clone.

Monensin-resistant mouse Balb/3T3 cell mutant with aberrant penetration of vesicular stomatitis virus

A mutant (MO-5) resistant to monensin (an ionophoric antibiotic) derived from the mouse Balb/3T3 cell line, was a poor host for vesicular stomatitis virus (VSV) or semliki forest virus (SFV) multiplication. The yield of VSV particles in MO-5 is one 100-fold reduced as is VSV-dependent RNA synthesis. In contrast to a pH-remedial mutant, the abortive production of infectious VSV particles in MO-5 cells was not restored by low pH treatment. The pH values in the endosome and the lysosome of MO-5 cells were 5.2 and 5.4, respectively, values that were comparable to the pH value in Balb/3T3 cells. Assays with [3H]uridine-labeled VSV indicated similar binding of VSV in MO-5: percoll gradient centrifugation analysis of [35S]methionine-labeled VSV-infected Balb/3T3 showed accumulation of VSV in the lysosome fraction 20 min after VSV infection, whereas VSV can be found mainly in endosome/Golgi fraction of MO-5 cells after 40 to 60 min on the percoll gradients. Degradation of [35S]methionine-labeled VSV was observed at a significant rate in Balb/3T3 cells, but not in MO-5 cells. The monensin-resistant somatic cell may thus provide a genetic route to study the mechanism of endocytosis or transport of enveloped viruses.

An immuno-electron microscopic study on intracellular localization of thyroglobulin (TG) in the thyroid gland in Grave's disease

Intracellular localization of thyroglobulin (TG) using a pre-embedding diffusion technique and an indirect localization sequence has been made in human thyroid obtained from 20 patients with treated Grave's disease. Both antibodies, anti-human TG-rabbit IgG F(ab')2 and anti-rabbit IgG F(ab')2-goat IgG F(ab')2 fragments easily penetrated the cytoplasm of follicular cells which were dissociated by RPMI-1640 solution containing collagenase, dispase, and deoxyribonuclease. With light microscopic observation of semithin sections positive immuno-reaction for TG was demonstrated as fine granular deposits in the cytoplasm of the dissociated cells. In electron microscopic studies, intracellular antigen was well circumscribed within certain cell organelles in all cases with the positive immuno-reaction for TG being observed in perinuclear space, rough endoplasmic reticulum, Golgi complexes, secretory granules, and reabsorbed colloid droplets. Content of positive immuno-reaction product differed somewhat from one case to another and from one follicle to another even in the same case. There was no immunoreaction product in nuclei, mitochondria, lysosomes, and lipofuscin-like granules.

Slow development of measles virus (Edmonston strain) infection in the brain of nude mice

The Edmonston strain of measles virus caused neurologic disease in athymic nude mice by intracerebral inoculation. The incubation periods of the disease, however, were extremely long, ranging from 59 to 140 days when the mice were inoculated with 10(4) plaque forming units (PFU) of the virus. The Edmonston strain was highly infectious in the nude mouse brain since virus infection was established even with 1 PFU of the virus. Virus titers in the brains of infected mice increased with the time of incubation. These results indicate that the extremely long incubation period of the disease is ascribed to very slow development of virus infection in the mouse brain. On the other hand, the incubation periods of the Biken strain of SSPE virus were very short (generally within 2 weeks) even with inoculations of 1 PFU of the virus. However, the extent of the dissemination of infection in brains was not significantly different between the two viruses as examined by immunofluorescent staining.

Methods of increasing the sensitivity of the haemagglutination inhibition test for rabies virus antibody

A new method for the removal of non-specific inhibitors of rabies virus haemagglutinin has been developed. Treatment with colloidal silicic acid (Aerosil) or with acetone plus Aerosil reduced the non-specific inhibitors in human, mouse, and dog sera to a level that was undetectable at the 1:4 starting dilution in the haemagglutination inhibition test.Bromelain-treated goose erythrocytes were much more susceptible to haemagglutination by rabies virus than were untreated erythrocytes, and the sensitivity of the haemagglutination inhibition test was considerably increased by using bromelain-treated erythrocytes. Low levels of antibodies in sera from immunized human subjects were detected with higher sensitivity by combining Aerosil treatment of the sera with the use of bromelain-treated goose erythrocytes in the haemagglutination inhibition test.

pH-dependent hemolysis and cell fusion of rhabdoviruses

Human erythrocytes pretreated with fungal semialkali protease or trypsin became susceptible to hemagglutination by vesicular stomatitis virus (VSV) and rabies virus. Both viruses exhibited extensive hemolytic and fusion activities against erythrocytes pretreated with these enzymes. The hemolysis and fusion were pH dependent and the activities were most apparent at pH 5.0 and decreased with increase in pH. However, VSV still exhibited slight hemolytic activity at neutral pH. Hemolysis was also dependent on the dose of virus and was inhibited by treatment of the viruses with antiviral antibody. Results of sodium dodecyl sulfate polyacrylamide gel electrophoresis of erythrocyte membranes suggested that most of the carbohydrates were removed from the membrane proteins by the treatment with proteolytic enzymes.

Demonstration of hemolytic and fusion activities of influenza C virus

Influenza C virus showed a marked hemolytic activity when incubated with murine erythrocytes at 37 degrees C in acidic medium. The virus-specific hemolysis was most efficient at pH 5.0. Extensive cell fusion also occurred when the erythrocytes were treated with the virus at acidic pH. When propagated in MDCK cells, the virus had an extremely low infectivity and did not display hemolytic activity in any pH range. When the inactive virus was subjected to mild trypsin treatment, hemolytic activity was drastically manifested, accompanying a drastic increase in infectivity. The glycoprotein in the inactive virus was cleaved into smaller components by trypsin treatments. These results indicated that the envelope of influenza C virus can fuse with the cellular membrane under acidic conditions and that the activation of influenza C virus by cleavage was due to the appearance of this envelope fusion activity.