Full genome-based characterization of G4P[6] rotavirus strains from diarrheic patients in Thailand: Evidence for independent porcine-to-human interspecies transmission events

The exact evolutionary patterns of human G4P[6] rotavirus strains remain to be elucidated. Such strains possess unique and strain-specific genotype constellations, raising the question of whether G4P[6] strains are primarily transmitted via independent interspecies transmission or human-to-human transmission after interspecies transmission. Two G4P[6] rotavirus strains were identified in fecal specimens from hospitalized patients with severe diarrhea in Thailand, namely, DU2014-259 (RVA/Human-wt/THA/DU2014-259/2014/G4P[6]) and PK2015-1-0001 (RVA/Human-wt/THA/PK2015-1-0001/2015/G4P[6]). Here, we analyzed the full genomes of the two human G4P[6] strains, which provided the opportunity to study and confirm their evolutionary origin. On whole genome analysis, both strains exhibited a unique Wa-like genotype constellation of G4-P[6]-I1-R1-C1-M1-A8-N1-T1-E1-H1. The NSP1 genotype A8 is commonly found in porcine rotavirus strains. Furthermore, on phylogenetic analysis, each of the 11 genes of strains DU2014-259 and PK2015-1-0001 appeared to be of porcine origin. On the other hand, the two study strains consistently formed distinct clusters for nine of the 11 gene segments (VP4, VP6, VP1-VP3, and NSP2-NSP5), strongly indicating the occurrence of independent porcine-to-human interspecies transmission events. Our observations provide important insights into the origin of zoonotic G4P[6] strains, and into the dynamic interaction between porcine and human rotavirus strains.

Immunomodulatory activity of Dioscorea membranacea Pierre rhizomes and of its main active constituent Dioscorealide B

BACKGROUND

The rhizomes of Dioscorea membranacea Pierre, also called Hua-Khao-Yen by Thai name, are used as ingredients in many Thai traditional medicines for the alternative or complementary treatment of cancer and AIDs. Preliminary in vitro studies have indicated that D. membranacea extracts exhibited high cytotoxic activity with several cancer cell lines, but the underlining mechanisms are far from clear. The aims of this study were to investigate the effects of ethanolic and aqueous crude extracts from D. membranacea Pierre, and pure compound from D. membranacea Pierre, Dioscorealide B, on natural killer cells activity and on lymphocyte proliferation.

METHODS

Immunomodulatory activity was investigated using PBMCs from healthy donors. NK cells activity was performed by the chromium release assay using PBMCs as effector cells, and K562 cells line labelled with chromium as target cells. Lymphocyte proliferation was determined by 3H-thymidine uptake. The degree of activation was expressed as the stimulation index.

RESULTS

The crude ethanolic extracts of D. membranacea Pierre significantly stimulated NK cells activity against K562 cells line at lower concentrations of 10 and 100 ng/ml, but not at higher concentrations. The ethanolic extracts showed no observable effect on lymphocyte proliferation. The crude water extracts significantly increased NK cell activity at concentrations of 10 ng/ml, 100 ng/ml, 1 μg/ml, 10 μg/ml and 100 μg/ml, and also activated lymphocyte proliferation at concentration of 1 ng/ml, 10 ng/ml, 100 ng/ml, 1 μg/ml, 5 μg/ml, 10 μg/ml and 100 μg/ml. However, Dioscorealide B had no significant effect at lower concentrations (0-1 μg/ml and 0-0.1 μg/ml, respectively) on NK cell activity and lymphocyte proliferation. In fact higher concentrations (>10 μg/ml and >0.5 μg/ml) of Dioscorealide B cause a significant decrease in NK cell activity and lymphocyte proliferation.

CONCLUSIONS

D. membranacea Pierre stimulated NK cells activity and lymphocyte proliferation, but Dioscorealide B either had no effect, and at higher concentrations decreased NK cell activity and lymphocyte proliferation. Our results suggest that both extracts of D. membranacea Pierre significantly increases immune function, but the underlining mechanism is not clearly understood.

Development of a novel in silico docking simulation model for the fine HIV-1 cytotoxic T lymphocyte epitope mapping

Introduction

Class I HLA's polymorphism has hampered CTL epitope mapping with laborious experiments. Objectives are 1) to evaluate the novel in silico model in predicting previously reported epitopes in comparison with existing program, and 2) to apply the model to predict optimal epitopes with HLA using experimental results.

Materials and Methods

We have developed a novel in silico epitope prediction method, based on HLA crystal structure and a peptide docking simulation model, calculating the peptide-HLA binding affinity at four amino acid residues in each terminal. It was applied to predict 52 HIV best–defined CTL epitopes from 15-mer overlapping peptides, and its predictive ability was compared with the HLA binding motif-based program of HLArestrictor. It was then used to predict HIV-1 Gag optimal epitopes from previous ELISpot results.

Results

43/52 (82.7%) epitopes were detected by the novel model, whereas 37 (71.2%) by HLArestrictor. We also found a significant reduction in epitope detection rates for longer epitopes in HLArestrictor (p = 0.027), but not in the novel model. Improved epitope prediction was also found by introducing both models, especially in specificity (p<0.001). Eight peptides were predicted as novel, immunodominant epitopes in both models.

Discussion

This novel model can predict optimal CTL epitopes, which were not detected by an existing program. This model is potentially useful not only for narrowing down optimal epitopes, but predicting rare HLA alleles with less information. By introducing different principal models, epitope prediction will be more precise.

The effect of HLA polymorphisms on the recognition of Gag epitopes in HIV-1 CRF01_AE infection

Introduction

The design of a globally effective vaccine rests on the identification of epitopes capable of eliciting effective cytotoxic T lymphocyte (CTL) responses across multiple HIV clades in different populations. This study aims to discern the effect of HLA polymorphisms and the cross-clade reactivity or clade-specificity of epitopes in Thailand where HIV-1 CRF01_AE is circulating.

Materials and Methods

14 peptides based on consensus HIV-1 CRF01_AE amino acid sequences were designed for use in IFN-γ ELISpot assays and ⁵¹Cr release assays among 66 HIV-1 CRF01_AE-infected Thai patients. For ELISpot responders carrying HLA alleles currently unknown to restrict CRF01_AE epitopes, in silico epitope-HLA prediction was performed.

Results

29/66 (43.9%) patients recognized at least one peptide. In total 79 responses were seen against all 14 peptides. 28/79 (35.4%) of the responses were in patients with HLA alleles previously reported to restrict CRF01_AE epitopes, 24/79 (30.4%) responses were in individuals with HLA alleles previously reported to restrict epitopes of HIV clades other than CRF01_AE, and the remaining 27/79 (34.2%) responses were not associated with HLA alleles previously known to restrict HIV epitopes. In silico epitope prediction detected 19 novel, epitope-HLA combinations, and 11/19 (57.9%) were associated with HLA-C alleles. We further confirmed a novel HLA restriction of a previously identified HIV-1 Gag epitope [p24_122–130: PPIPVGDIY (PY9)] by HLA-B*40:01 with a standard ⁵¹Cr release assay.

Discussion

CTL recognition sites in HIV-1 Gag were similar among different clades but the HLA restriction differed in Thai patients. This disparity in HLA restriction along different populations illustrated the importance of clade- and population-specific HLA analysis prior to CTL vaccine design.

Unique CRF01_AE Gag CTL epitopes associated with lower HIV-viral load and delayed disease progression in a cohort of HIV-infected Thais

Cytotoxic T Lymphocytes (CTLs) play a central role in controlling HIV-replication. Although numerous CTL epitopes have been described, most are in subtype B or C infection. Little is known about CTL responses in CRF01_AE infection. Gag CTL responses were investigated in a cohort of 137 treatment-naïve HIV-1 infected Thai patients with high CD4+ T cell counts, using gIFN Enzyme-Linked Immunospot (ELISpot) assays with 15-mer overlapping peptides (OLPs) derived from locally dominant CRF01_AE Gag sequences. 44 OLPs were recognized in 112 (81.8%) individuals. Both the breadth and magnitude of the CTL response, particularly against the p24 region, positively correlated with CD4+ T cell count and inversely correlated with HIV viral load. The breadth of OLP response was also associated with slower progression to antiretroviral therapy initiation. Statistical analysis and single peptide ELISpot assay identified at least 17 significant associations between reactive OLP and HLA in 12 OLP regions; 6 OLP-HLA associations (35.3%) were not compatible with previously reported CTL epitopes, suggesting that these contained new CTL Gag epitopes. A substantial proportion of CTL epitopes in CRF01_AE infection differ from subtype B or C. However, the pattern of protective CTL responses is similar; Gag CTL responses, particularly against p24, control viral replication and slow clinical progression.

HLA-associated immune pressure on Gag protein in CRF01_AE-infected individuals and its association with plasma viral load

Background

The human leukocyte antigen (HLA)-restricted cytotoxic T-lymphocyte (CTL) immune response is one of the major factors determining the genetic diversity of human immunodeficiency virus (HIV). There are few population-based analyses of the amino acid variations associated with the host HLA type and their clinical relevance for the Asian population. Here, we identified HLA-associated polymorphisms in the HIV-1 CRF01_AE Gag protein in infected married couples, and examined the consequences of these HLA-selected mutations after transmission to HLA-unmatched recipients.

Methodology/Principal Findings

One hundred sixteen HIV-1-infected couples were recruited at a government hospital in northern Thailand. The 1.7-kb gag gene was amplified and directly sequenced. We identified 56 associations between amino acid variations in Gag and HLA alleles. Of those amino acid variations, 35 (62.5%) were located within or adjacent to regions reported to be HIV-specific CTL epitopes restricted by the relevant HLA. Interestingly, a significant number of HLA-associated amino acid variations appear to be unique to the CRF01_AE-infected Thai population. Variations in the capsid protein (p24) had the strongest associations with the viral load and CD4 cell count. The mutation and reversion rates after transmission to a host with a different HLA environment varied considerably. The p24 T242N variant escape from B57/58 CTL had a significant impact on the HIV-1 viral load of CRF01_AE-infected patients.

Conclusions/Significance

HLA-associated amino acid mutations and the CTL selection pressures on the p24 antigen appear to have the most significant impact on HIV replication in a CRF01_AE-infected Asian population. HLA-associated mutations with a low reversion rate accumulated as a footprint in this Thai population. The novel HLA-associated mutations identified in this study encourage us to acquire more extensive information about the viral dynamics of HLA-associated amino acid polymorphisms in a given population as effective CTL vaccine targets.

Application of Streptomyces and Brevibacterium cholesterol oxidase for total serum cholesterol assay by the enzymatic kinetic method

BACKGROUND

Using non-esterified cholesterol standard, Brevibacterium and Streptomyces are found as suitable sources of cholesterol oxidase for kinetic cholesterol assay. For clinical use, we investigated the suitability of these enzymes for cholesterol determination in human serum.

METHODS

We compared the performance of reagents containing 2 enzymes for the kinetic determination of total serum cholesterol with the standardized endpoint method.

RESULTS

Reagent containing Streptomyces enzyme was more sensitive than that of Brevibacterium, with linearity up to 20.7 and 2.6 mmol/l, respectively. The analytical reaction for Streptomyces showed a shorter lag phase (148 s) and a steeper slope (absorbance vs. time) than that of Brevibacterium (246 s). The assay using Streptomyces reagent was precise and accurate and compared favorably with the endpoint method (y=1.06x-0.15, r=0.996, bias=0.21 mmol/l). Hemoglobin as high as 7.5 g/l did not interfere while turbidity greater than 2+ (absorbance >0.778 at 670 nm) and bilirubin concentrations >171.0 micromol/l did interfere (in a negative interference). Reagent was stable up to at least 8 weeks.

CONCLUSIONS

The Streptomyces cholesterol oxidase, with 3,4-dichlorophenol, proved a suitable source for serum total cholesterol determination by the kinetic method.

Performance of four sources of cholesterol oxidase for serum cholesterol determination by the enzymatic endpoint method

BACKGROUND

Cholesterol oxidase is used for the determination of serum cholesterol. It can be derived from Streptomyces, Pseudomonas fluorescens, Cellulomonas, and Brevibacterium. This study compared the performance characteristics of four enzymes in the endpoint cholesterol determination.

METHODS

Using the Mega analyzer, we studied assay optimization, linearity, precision, recovery, interference, stability, and compared 110 patient samples.

RESULTS

The linearity for the four enzymes was up to 13.0 mmol/l at the optimal enzyme activity. The average within-run CVs ranged from 1.6% to 1.9% and between-day ranged from 2.8% to 3.0%, within the NCEP analytical criteria. The analytical recoveries obtained from four reagents ( approximately 96.5%) were excellent. The assays using these enzyme sources compared favorably with the commercial method and appeared accurate near the clinical decision cut-points. Hemoglobin concentration at 1.9 g/l interfered with the P. fluorescens cholesterol oxidase. Bilirubin caused a negative interference while lipemia generated a positive interference with all enzyme sources. Reagents were stable up to 6 weeks.

CONCLUSIONS

Streptomyces, Cellulomonas, and Brevibacterium were essentially analytically equivalent. Streptomyces and Cellulomonas cholesterol oxidase are one-quarter as expensive Brevibacterium. Cellulomonas is a new source of cholesterol oxidase for determining serum cholesterol by the endpoint method.

A study to implement early diagnosis of HIV infection in infants born to infected mothers

A protocol for detecting HIV DNA from specimens collected on filter papers and the effect of storage temperatures on determination of HIV DNA from dried blood spots has been developed and optimized. Blood specimens collected from HIV-1 infected and normal persons were spotted onto blood collection cards (Whatman BFC 180). The HIV DNA was extracted by phenol-chloroform-isoamyl alcohol and was detected for C2V4 of HIV-1 env by nested polymerase chain reaction (nested PCR). One set was stored at -20 degrees C for 14 weeks, another at 37 degrees C for 1 week and then kept at -20 degrees C for 13 weeks and a third set at 25 degrees C for I week and then -20 degrees C for 13 weeks. The dried blood spots from each set were detected for the HIV DNA every 2 weeks for 14 weeks. The C2V4 region of HIV env DNA was determined from small amounts of the dried blood collected on the filter papers. The nested PCR procedure could detect as few as 5 copies of HIV proviral DNA, and HIV DNA could be detected from specimens with viral loads of 2x 10(4) copies/ml. HIV DNA could be detected from specimens collected at all temperatures tested for at least 14 weeks. Therefore, laboratory diagnosis of HIV infection can be done by PCR on dried blood spots. These techniques will be useful as a tool for studying the epidemiology of HIV infection among populations of interest such as mother to child infection using newborn screening specimens.

In vitro effect of Derris scandens on normal lymphocyte proliferation and its activities on natural killer cells in normals and HIV-1 infected patients

We investigated the effect of Derris scandens hydroalcoholic extract on lymphocyte proliferation, natural killer (NK) cell activity and secretion of IL-2 and IL-4. Lymphocyte proliferative response of normal individuals was significantly increased at concentrations of 10 ng/ml, 100 ng/ml, 1 microg/ml and 5 microg/ml, whereas the response was significantly decreased at 100 microg/ml. D. scandens at the concentrations of 10 ng/ml, 100 ng/ml, 1 microg/ml and 10 microg/ml significantly enhanced the function of NK cells of normal individuals. The NK cell activity of HIV-infected individuals was significantly increased at a concentration of 10 microg/ml. Furthermore, the extract was shown to induce the IL-2 secretion from normal peripheral blood mononuclear cells (PBMC), whereas the IL-4 was not induced in the presence of the D. scandens extract. Our data suggested that the hydroalcoholic extract of D. scandens possesses in vitro immunostimulating activity on human immunocompetent and immunocompromised PBMC.

HIV-specific cytotoxic T lymphocytes, HLA-A11, and chemokine-related factors may act synergistically to determine HIV resistance in CCR5 delta32-negative female sex workers in Chiang Rai, northern Thailand

Understanding how highly HIV-exposed individuals remain HIV uninfected may be useful for HIV vaccine design and development of new HIV prevention strategies. To elucidate mechanisms associated with resistance to HIV infection, immunologic and genetic factors were examined in 14 HIV-exposed but persistently seronegative (HEPS) female sex workers from Chiang Rai, northern Thailand and in ethnically matched, HIV-positive (n = 9) and HIV-negative women (n = 9). The HEPS women were identified in a study of commercial sex workers who had an HIV-1 incidence of 20.3 per 100 person-years. A high frequency of HLA-A11 was observed in HEPS women (86%) compared with northern Thai controls (56%). HIV-specific cytotoxic T lymphocyte (CTL) lytic responses were detected in cryopreserved peripheral blood mononuclear cells (PBMCs), using HLA-A-matched subtype E HIV-1 peptides in four of seven (57%) HEPS women, eight of eight HIV-positive women, and zero of nine HIV-negative unexposed controls (p = 0.019 HEPS women vs. HIV-negative controls). CTL lysis levels were low, but responses were detected to peptides from Nef, Pol, Gag, and Env. Nef responses predominated in HEPS women. Compared with controls, HEPS women tended to have higher frequencies of CCR5 promotor 59402GG and SDF-1 3'UTR 801A genotypes known to influence HIV transmission or course of disease. HEPS women also had higher levels of spontaneous RANTES production by PBMCs than other groups. Each of these factors could potentially contribute to HIV resistance. As most HEPS women had one or more of these factors, they may prevent HIV infection synergistically by blocking HIV cell entry, delaying its dissemination, or killing HIV-infected cells.

An HLA-directed molecular and bioinformatics approach identifies new HLA-A11 HIV-1 subtype E cytotoxic T lymphocyte epitopes in HIV-1-infected Thais

Only limited cytotoxic T lymphocyte (CTL) epitope mapping has been done in nonsubtype B HIV-infected persons. We used molecular immunogenetic tools to determine HIV-specific CTL responses in HIV-1 Env subtype E-infected female sex workers (FSWs) from northern Thailand, where more than 50% of the population is HLA-A11 positive. EpiMatrix, a computer-based T cell epitope prediction algorithm, and a manual editing approach were used to predict 77 possible HLA-A11 CTL epitopes in HIV-1, some of which were conserved between subtypes B and E. MHC binding of these peptides was determined in an HLA-A11 stabilization assay, and binding peptides were tested for CTL recognition in eight HLA-A11-positive FSWs. Subtype E versions of known HLA-A2 subtype B HIV epitopes were also tested in four HLA-A2 positive FSWs. CTL responses were detected in all HLA-A11-positive and in three of four HLA-A2-positive persons. Among the 12 FSWs responses to peptides were found to Pol in 9 (75%), Env in 7 (58%), Nef in 5 (42%), and Gag in 5 (42%), and to conserved epitopes in 8 (67%). To identify HLA-A11 CTL epitopes in the absence of prediction tools, it would have been necessary to test almost 3000 10-mer peptides. EpiMatrix and manual predictions reduced this number to 77, of which 26 were MHC binding and 12 were CTL epitopes. Six of these HLA-A11 CTL epitopes have not been previously reported and are located in RT, gp120, and gp41. This report of CTL responses in subtype E-infected individuals defines epitopes that may be useful in HIV pathogenesis or vaccine studies.

Single-step purification of Proteus mirabilis urease accessory protein UreE, a protein with a naturally occurring histidine tail, by nickel chelate affinity chromatography

Proteus mirabilis urease, a nickel metalloenzyme, is essential for the virulence of this species in the urinary tract. Escherichia coli containing cloned structural genes ureA, ureB, and ureC and accessory genes ureD, ureE, ureF, and ureG displays urease activity when cultured in M9 minimal medium. To study the involvement of one of these accessory genes in the synthesis of active urease, deletion mutations were constructed. Cultures of a ureE deletion mutant did not produce an active urease in minimal medium. Urease activity, however, was partially restored by the addition of 5 microM NiCl2 to the medium. The predicted amino acid sequence of UreE, which concludes with seven histidine residues among the last eight C-terminal residues (His-His-His-His-Asp-His-His-His), suggested that UreE may act as a Ni2+ chelator for the urease operon. To exploit this potential metal-binding motif, we attempted to purify UreE from cytoplasmic extracts of E. coli containing cloned urease genes. Soluble protein was loaded onto a nickel-nitrilotriacetic acid column, a metal chelate resin with high affinity for polyhistidine tails, and bound protein was eluted with a 0 to 0.5 M imidazole gradient. A single polypeptide of 20-kDa apparent molecular size, as shown by sodium dodecyl sulfate-10 to 20% polyacrylamide gel electrophoresis, was eluted between 0.25 and 0.4 M imidazole. The N-terminal 10 amino acids of the eluted polypeptide exactly matched the deduced amino acid sequence of P. mirabilis UreE. The molecular size of the native protein was estimated on a Superdex 75 column to be 36 kDa, suggesting that the protein is a dimer. These data suggest that UreE is a Ni(2)+-binding protein that is necessary for synthesis of a catalytically active urease at low Ni(2+) concentrations.

Sequence of the Proteus mirabilis urease accessory gene ureG

We report the sequence of ureG, an accessory gene that is a part of the ure gene cluster of uropathogenic Proteus mirabilis and required for full enzymatic activity of urease. The 615-bp open reading frame predicts a M(r) 22,374 polypeptide, which contains a consensus amino acid (aa) sequence for ATP-binding. The polypeptide shares sequence homology with UreG of Escherichia coli (93% of identical aa), Klebsiella aerogenes (59%) and Helicobacter pylori (59%).

Proteus mirabilis urease: histidine 320 of UreC is essential for urea hydrolysis and nickel ion binding within the native enzyme

Proteus mirabilis urease, a nickel-containing enzyme, has been established as a critical virulence determinant in urinary tract infection. An amino acid sequence (residues 308 to 327: TVDEHLDMLMVCHHLDPSIP) within the large urease subunit, UreC, is highly conserved for every urease examined thus far and has been suggested to reside within the enzyme active site. Histidine residues have been postulated to play a role in catalysis by coordinating Ni2+ ions. To test this hypothesis, oligonucleotide-directed mutagenesis was used to change amino acid His-320 to Leu-320 within UreC. The base change (CAT for His-320 to CTT for Leu-320) was confirmed by DNA sequencing. The recombinant and mutant proteins were expressed at similar levels in Escherichia coli as detected by Western blotting (immunoblotting) of denaturing and nondenaturing gels. Specific activities of the enzymes were quantitated after partial purification. Strains expressing the mutant enzyme showed no detectable activity, whereas strains expressing the recombinant enzyme hydrolyzed urea at 149 mumol of NH3 per min per mg of protein. In addition, the mutant enzyme was able to incorporate only about one-half (58%) of the amount of 63Ni2+ incorporated by the active recombinant enzyme. While the mutation of His-320 to Leu-320 within UreC does not affect expression or assembly of urease polypeptide subunits UreA, UreB, and UreC His-320 of UreC is required for urea hydrolysis and proper incorporation of Ni2+ into apoenzyme.

Lymphocyte subsets in human encephalitic and paralytic rabies

Lymphocyte subsets of 7 patients with encephalitic and paralytic rabies were determined by immunocytochemical techniques using mouse monoclonal antibodies. Almost all patients had diminished mononuclear cells of Leu 7 phenotype (natural killer cells). Cells of Leu 12 marker (B cells) were decreased in 3 paralytic rabies patients compared with those of 4 patients in the encephalitic group.

Comparative immunogenicity study of four plasma-derived hepatitis B vaccines in Thai young adults

Immunogenicity of four plasma-derived hepatitis B vaccines (Merck, Sharp and Dohme, Pasteur, Dutch CLB and Korean Cheil-Sugar) was compared in Thai young adults. After primoimmunization, only the Merck and Pasteur vaccines could achieve greater than 90% seroconversion (i.e. anti-HBs greater than or equal to 10 mIU ml-1) whereas both the CLB and Korean vaccines needed a fourth dose to achieve this level of seroconversion. The anti-HBs titres of both heat-inactivated vaccines (CLB and Korean) were also significantly lower than those of the other two vaccines. We propose that the HBsAg content in both heat-inactivated vaccines should be increased and a booster (fourth) dose should be given in order to enhance their immunogenicities.

Immunoenhancement with combined rabies and aluminium-adjuvanted tetanus vaccines

The effect of combining tetanus toxoid in the same syringe with purified Vero cell rabies vaccine (PVRV) was investigated in the 2-1-1 regimen of PVRV. The 2-1-1 regimen alone was as immunogenic as the five-dose regimen, while saving one dose of vaccine and two clinic visits. When aluminium hydroxide-adsorbed tetanus toxoid was used to dissolve PVRV on days 0 (one of the two doses) and 21, the anti-rabies antibody was significantly increased. Aluminium-free tetanus toxoid was ineffective, suggesting that immunoenhancement was due to aluminium adjuvant. In addition, anti-tetanus antibody was unaffected and the side-effects were not increased by such mixing.

Immunologic study of human encephalitic and paralytic rabies. Preliminary report of 16 patients

Lymphocyte proliferation tests to rabies antigen and myelin basic protein were performed on peripheral blood lymphocytes from nine patients with the encephalitic form and on seven with the paralytic form of human rabies. Six of the nine patients with encephalitis had proliferative responses to rabies antigen, whereas all of the patients with paralysis had no response. Two patients in each group also had a proliferative response to myelin basic protein. The myelin basic protein-reactive patients had a more rapidly fatal disease than the non-reactive patients. This preliminary study suggests that host immune responses may influence the clinical manifestations and course in human rabies.

Effect of inosiplex on the humoral and cell-mediated immune responses to intradermal human diploid cell rabies vaccine

Antigen-stimulated lymphocyte transformation was studied in recipients of intradermal human diploid cell rabies vaccine (HDCV). HDCV was administered intradermally at 8 different anatomical sites, 0.1 ml each, on day 0; followed by another 4-site injection on day 7. Rabies antigen-stimulated in vitro proliferative response was evident as early as 7 days after starting immunization. It reached a peak on day 14 and had declined by day 28. The cellular proliferative response preceded and roughly correlated with the antirabies antibody response. Simultaneous administration of inosiplex, an antiviral and immunopotentiating drug, during the first 10 days of intradermal HDCV immunization did not result in heightened antibody titres or cell-mediated immune response to the vaccine. The number of T cells and the lymphocyte proliferative response to phytohaemagglutinin in inosiplex-treated vaccinees were similarly not significantly different from untreated controls. Our results confirm other previous findings that a specific cell-mediated immune response can be consistently and rapidly induced by an intradermal regimen of HDCV immunization. The addition of inosiplex to this regimen did not enhance the humoral or cell-mediated immune responses to the vaccine. The apparent lack of immunostimulating effect of inosiplex in this setting may be the result of several factors such as the immunization schedule and the immunologic parameters examined.

Cell-mediated immune response following intracutaneous immunisation with human diploid cell rabies vaccine

Specific cell-mediated immune response (CMIR) against rabies antigens was studied in recipients of two regimens of human diploid cell rabies vaccine (HDCV) using the antigen-stimulated lymphocyte transformation test (LTT) as a measure of CMIR. Reconstituted HDCV could be conveniently used as the in vitro stimulating antigen and the response was antigen-dependent. Conventional intramuscular immunization with full-dose HDCV resulted in positive LTT as early as 14 days after starting immunisation, and peaked on day 28. Intracutaneous immunisation with 0.1 ml of HDCV at four sites on days 0, 3 and 7 was a more efficient means of inducing specific lymphocyte response. Specific CMIR was evident as early as seven days and became maximal on day 14. In addition to the more rapid induction of specific CMIR, our intracutaneous regimen also resulted in a brisker and higher antibody response than the intramuscular regimen. The peak antibody level of the intracutaneous regimen was reached on day 14 whereas that of the intramuscular regimen was reached on day 28 and the geometric mean antibody titre on day 14 of the intracutaneous route was significantly higher than that of the intramuscular regimen. We therefore conclude that our closely spaced intracutaneous immunisation with HDCV was effective both in the induction of specific antibodies and the cell-mediated immune response.