Proximal myotonic myopathy: evidence for anticipation in families with linkage to chromosome 3q

OBJECTIVE

To investigate anticipation in proximal myotonic myopathy (PROMM).

BACKGROUND

PROMM is a recently described autosomal dominantly inherited disorder similar to but distinct from myotonic dystrophy (DM). DM belongs to the group of inherited disorders with anticipation caused by an unstable trinucleotide repeat expansion. In PROMM, no mutation has been identified, although PROMM has recently been mapped to a gene locus on chromosome 3q.

METHODS

We investigated 10 German families with the PROMM phenotype and linkage to chromosome 3q. We based our analysis of anticipation on the age of disease onset. Anticipation was assumed if the offspring had first symptoms earlier in life than his or her affected parent. For statistical analysis Independence Estimating Equations (IEE) and a Monte-Carlo bootstrap were used.

RESULTS

In 27 affected living parent-offspring pairs from these 10 families, the mean difference of disease onset was 18.8 years with either statistical analysis (p < 10-14 and p < 10-15). The mean disease onset interval in years was greater in father-offspring as compared to the mother-offspring pairs (p < 0.05; IEE).

CONCLUSION

Our findings suggest the occurrence of anticipation in parent-offspring pairs from families with the PROMM phenotype and linkage to chromosome 3q. The different disease onset intervals in mother-offspring and father-offspring pairs could indicate a mild parent-of-origin effect. These observations are compatible with the suggestion that PROMM, like DM, may be a trinucleotide repeat associated disorder. In contrast to DM, anticipation in PROMM is milder, a congenital form does not seem to occur, and fertility does not appear to be affected.

Determination of morphine 3-esters in rabbit plasma by high-performance liquid chromatography with ultraviolet detection

A sensitive high-performance liquid chromatographic (HPLC) method for the quantitation of the morphine 3-esters 1[3-(2, 2-dimethylvaleroyl)-morphine (A), 3-(2-phenylbenzoyl)-morphine (B) and 3-(2,2-diphenylpropionyl)-morphine (C)] in rabbit plasma is described. Sample preparation was based on reversed-phase solid-phase extraction. The compounds were separated on C(18) reversed-phase analytical columns and then determined by ultraviolet detection. The recovery from plasma was 78.7 +/- 7.4%, 69.1 +/- 6.9% and 75 +/- 7.2% (mean +/- SD) for A, B, and C, respectively. The present method enabled the detection limit of 0.2, 0.2 and 0.1 ng and quantification limit of 20, 10 and 10 ng/ml for A, B and C, respectively. The developed method was used for determination of the plasmakinetics of these morphine 3-esters in rabbits.

Mapping of leukaemia-associated breakpoints in chromosome band 3q21 using a newly established PAC contig

Chromosome aberrations affecting band 3q21 are associated with a particularly poor prognosis in patients with acute myeloid leukaemia. To facilitate the molecular characterization of such rearrangements, we established a PAC contig covering the relevant genomic region. Using these PACs as probes in fluorescence in situ hybridization (FISH) experiments, we showed that a number of 3q21 breakpoints in patient samples map to a previously defined 'breakpoint cluster region'. Others, however, are located at varying distances centromeric of it. These results have important implications in the search for genes affected by 3q21 rearrangements.

Development of celiac disease-associated antibodies in offspring of parents with type I diabetes

AIMS/HYPOTHESIS

The aim of this study was to determine the frequency and temporal development of antibodies related to celiac disease in offspring of parents with Type I (insulin-dependent) diabetes mellitus.

METHODS

Sera from 913 offspring of parents with Type I diabetes prospectively followed from birth to the age of 8 years were tested for IgG-transglutaminase antibodies (IgG-tTGCAs), endomysial IgA antibodies (EMA) and gliadin antibodies.

RESULTS

We found tTGCAs in 32 (3.5%) of the 913 relatives. Prevalence was related to age and reached 6.5% at age 8 years. Endomysial IgA antibodies were detected in 44% of the relatives with tTGCAs and 0.6% of tTGCA negative relatives and were also most prevalent (5 %) in those aged 8 years. Both tTGCAs and EMAs were more frequent in relatives with the HLA DRB1*03 DQA1*0501 DQB1*02 haplotype (7.1% and 7.2%, respectively; p < 0.005). Antigliadin antibodies were common in both tTGCA positive (42%) and negative (23%) relatives, did not show a relation with age and were less prevalent in relatives with HLA DR3 (p < 0.05). There was no association between the presence of antibodies associated with celiac disease and islet autoantibodies in these relatives. Of the relatives 15 (1.6%) had tTGCAs plus EMAs. In two of these, anti-gliadin antibodies were detected before the detection of tTGCAs and EMAs at the age of 9 months whereas none of the remainder had any antibodies associated with celiac disease before age 2 years. In three there were no detectable antigliadin antibodies in any of the samples tested. Celiac disease without clinical symptoms was diagnosed in 9 of 12 by intestinal biopsy. CONCLUSION/INTERPRETATION. A statistically significant proportion of relatives of patients with Type I diabetes have celiac disease-associated autoimmunity and the silent form of celiac disease early in life. These relatives should, therefore, be considered for celiac antibody screening.

Independent confirmation of a major locus for obesity on chromosome 10

Linkage results obtained in genome-wide scans for complex phenotypes require confirmation in independent samples. Recently, linkage of obesity to chromosome 10p12 with a maximal multipoint LOD score of 4.85 was reported upon use of an affected sib-pair approach including nuclear families in which the adult index case had a BMI > or = 40 kg/m2 and at least one further sibling had a BMI > or = 27 kg/m2 (Hager et al., 1998, Nat Genet 20:304-8). To attempt to replicate this linkage finding we genotyped 11 markers spanning approximately 23 cM from 10p13 to 10ql1 in a total of 386 individuals stemming from 93 nuclear families with two or more young obese offspring with a BMI > or = 90th age percentile. The highest multipoint maximum likelihood binomial (MLB) LOD score using the extreme concordant sib-pair approach in which one sib had a BMI > or = 95th percentile, and other sibs a BMI > or = 90th percentile was 2.32. Six markers yielded nominal p-values < 0.05, the highest two point MLB-LOD score of 2.45 (nominal p = 0.0004) was obtained for the marker TCF8. Transmission disequilibrium tests for the most frequent parental allele yielded no nominal p-value < 0.05. The linkage results confirm the presence of a major susceptibility locus for obesity in a region near the centromere on chromosome 10.

No major association of breast-feeding, vaccinations, and childhood viral diseases with early islet autoimmunity in the German BABYDIAB Study

OBJECTIVE

Environmental factors have been suggested to play an important role in the pathogenesis of type 1 diabetes. The aim of this study was to assess the influence of breast-feeding, vaccinations, and childhood viral diseases on the initiation of islet autoimmunity in early childhood.

RESEARCH DESIGN AND METHODS

Data were prospectively collected from questionnaires obtained at birth, at 9 months of age, and at 2 years of age in 823 offspring from parents with type 1 diabetes. By 2 years of age, 31 offspring had islet antibodies, and 10 developed overt diabetes by the time of follow-up.

RESULTS

In offspring from mothers with type 1 diabetes, duration of exclusive and total breast-feeding did not differ between islet antibody-positive and -negative children, regardless of HLA genotype, and breast-feeding of 3 months or longer was not associated with protection from antibody development or diabetes onset. In offspring from diabetic fathers, non-statistically significant reductions in exclusive and total breast-feeding times were observed in the antibody-positive cohort. Neither type nor quantity of vaccinations (including Bacille Calmette-Guerin vaccine; haemophilus influenzae vaccine; diphtheria, tetanus, and pertussis vaccine; tick-born encephalitis vaccine; or measles, mumps, and rubella vaccine) were associated with the development of islet antibodies and diabetes. Measles, mumps, and rubella were not reported in children with islet antibodies or diabetes.

CONCLUSIONS

This study showed no evidence that proposed environmental factors affect islet antibody development in the first 2 years of life in offspring from parents with type 1 diabetes.

Extensive gene duplications and a large inversion characterize the human leukocyte receptor cluster

The chromosomal region 19q13.4 harbors the human leukocyte receptor cluster (LRC) which has been demonstrated to contain 19 genes encoding leukocyte-expressed receptors of the immunoglobulin (Ig) superfamily. A spotted PAC library was used to construct a contig of 65 overlapping clones spanning the complete LRC. Within the 900 kb covered by the contig, we identified one cluster containing killer cell inhibitory receptor genes and two clusters containing Ig-like transcript (ILT) genes. Of these, the second ILT cluster, located at the centromeric end of the LRC, was previously unknown. Detailed analysis of the ILT receptor genes in this cluster revealed one novel (ILT11) and six already known ILT genes. The two ILT clusters are transcribed in opposite directions and are separated by about 200 kb, which contains two leukocyte-associated inhibitory receptor (LAIR) genes. The data suggest that the two ILT clusters, each including one LAIR locus, arose from a single ancestral ILT/LAIR cluster by inverse duplication of a c large genomic fragment. Furthermore, the NK cell-expressed NKp46 gene was localized 20 kb telomeric of FCAR; and 14 novel genes mapping within the LRC were identified by cDNA selection. Together with the gene for the ribosomal protein S9 (RPS9), which had previously been assigned to 19q13.4, the total number of LRC genes is now 44. Of these, 29 belong to the Ig superfamily.

Morphometric analysis of the calcium-transporting sternal epithelial cells of the terrestrial isopods Ligia oceanica, Ligidium hypnorum, and Porcellio scaber during molt

Isopods shed first the posterior and then the anterior half of the body. Before molt, most terrestrial species resorb CaCO3 from the posterior mineralized cuticle. The mineral is stored in anterior sternal deposits, which are used to calcify the new posterior cuticle after molt. For Porcellio scaber it is known that the anterior sternal epithelium has specific structural differentiations for epithelial transport. These differentiations include the plasma membrane surface areas, and the volume fraction of the mitochondria. We analyzed the ultrastructure of the sternal epithelium and used a morphometric approach to study the variations of these parameters between species living in different terrestrial environments. In Ligidium hypnorum, which lives in moist environments, the plasma membrane surface area and volume fraction of mitochondria are much larger than in the semiterrestrial Ligia oceanica. This is in accordance with the relatively larger CaCO3 deposits and shorter time intervals for their formation and resorption in L. hypnorum. For P. scaber, which is adapted to mesic habitats, most values are between those of L. oceanica and L. hypnorum. However, P. scaber has even larger CaCO3 deposits which are formed and degraded within similar time intervals as in L. hypnorum. This unexpected result is considered from the standpoint of more effective mechanisms being present for epithelial ion transport.

Transcription factor GATA-2 gene is located near 3q21 breakpoints in myeloid leukemia

Rearrangements affecting chromosome band 3q21 are observed in a subgroup of patients with acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). However, little is known about the molecular consequences of such aberrations. We therefore established a PAC contig in the 3q21 breakpoint region and identified potential protein coding sequences by exon trapping. One of the exons isolated was from the human GATA-2 gene, which we showed to be transcribed from telomere to centromere. The majority of 3q21 breakpoints are located telomeric to the transcribed portion of this gene in a region that in mice appears to be necessary for proper promoter function. Results of GATA-2 expression analyses in leukemic cell lines as well as primary patient samples are compatible with the hypothesis that 3q21 aberrations contribute to leukemogenesis through deregulation of the hematopoietic transcription factor GATA-2.

Identifying influential families using regression diagnostics for generalized estimating equations

The Generalized Estimating Equations (GEE) is an approach to analyze correlated data. It is applied here to data from an epidemiological study of oesophageal cancer in a high incidence area in China to investigate familial aggregation. Regression diagnostics for mean structures and association structures are used to identify families that influence estimates of these structures. It is shown that most of the families influencing the mean structure have a low age of disease onset in common. Most families identified by regression diagnostics for the association structure influence the parent correlation. It is concluded that regression diagnostic techniques can be used to identify clusters influencing mean and association structures of the models.

Sample size calculations for linkage analysis using extreme sib pairs based on segregation analysis with the quantitative phenotype body weight as an example

One approach to establish linkage is based on allele-sharing methods for sib pairs. Recently, the use of extreme sib pairs (ESP) has been proposed to increase power for mapping quantitative traits in humans. Several approaches have been discussed. In this study, we calculate sample sizes for the various ESP approaches using segregation analyses of quantitative traits. We illustrate this approach by using previously published segregation analyses of body weight despite the fact that the assumptions imposed by these analyses do not hold up for this quantitative phenotype.

In vivo 129Xe NMR in rat brain during intra-arterial injection of hyperpolarized 129Xe dissolved in a lipid emulsion

Hyperpolarized 129Xe was dissolved in a lipid emulsion and administered to anaesthetized rats by manual injections into the carotid (approximately 1-1.5 mL in a maximum time of 30 s). During injection, 129Xe NMR brain spectra at 2.35 T were recorded over 51 s, with a repetition time of 253 ms. Two peaks assigned to dissolved 129Xe were observed (the larger at 194 +/- 1 ppm assigned to intravascular xenon and the smaller at 199 +/- 1 ppm to xenon dissolved in the brain tissue). Their kinetics revealed a rapid intensity increase, followed by a plateau (approximately 15 s duration) and then a decrease over 5 s. This behaviour was attributed to combined influences of the T1 relaxation of the tracer, of radiofrequency sampling, and of the tracer perfusion rate in rat brain. Similar kinetics were observed in experiments carried out on a simple micro-vessel phantom. An identical experimental set-up was used to acquire a series of 2D projection 129Xe images on the phantom and the rat brain.

Exposure to exogenous insulin promotes IgG1 and the T-helper 2-associated IgG4 responses to insulin but not to other islet autoantigens

Insulin immunization in animal models induces T-helper (Th) 2-like antibody subclass responses to insulin and other beta-cell antigens. The aim of this study was to determine whether exposure to insulin in humans resulted in a similar subclass bias of the humoral immune response. Levels of IgG subclass antibodies to insulin (IAs), GAD, and IA-2 were measured before and after treatment with insulin in the following groups of patients: 29 patients with newly diagnosed type 1 diabetes treated with intravenous and/or subcutaneous insulin; 10 newly diagnosed patients randomized to cyclosporin A (CsA) or placebo plus subcutaneous insulin for 12 months; and 14 islet cell antibody-positive relatives receiving either intravenous and subcutaneous insulin prophylaxis or no treatment. At the onset of diabetes, the major subclass distributions of insulin autoantibodies (IAAs) were IgG1 and, to a lesser extent, IgG4. After insulin treatment in the 29 new-onset patients, IAs were initially of the IgG1 subclass. IgG4-IAs appeared later, but at 12 months, they were at higher levels than IgG1-IAs in 11 patients. Responses were higher in children compared with adults and were higher in subjects with IAAs (P < 0.001). Insulin prophylaxis in relatives showed a similar profile, with a decline in levels of IgG1-IAs after cessation of daily subcutaneous insulin. Patients treated with CsA took longer to develop IAs and showed suppressed levels of IgG4-IAs; however, their levels of high-titer IgG1-IAs persistently rebounded after completion of CsA therapy. Despite the presence of IgG4-IAs in most insulin-treated patients and relatives, a shift to IgG4-anti-GAD or IgG4-IA-2 was not found for up to 3 years after the initiation of insulin therapy. While our findings need to be correlated with T-cell cytokine responses, we suggest that the strong IgG4-IA response in insulin-treated patients is consistent with an enhancement of Th2 immunity, but there is no evidence of subsequent spreading of potentially Th2-associated IgG4 responses to other autoantigens.

Short treatments of normotensive and hypertensive rats by angiotensin II and nitric oxide inhibitor induce an increase of noradrenaline sensitivity in isolated vena portae preparations

The aim of the study was to examine the influence of a short-term treatment of conscious Wistar Kyoto rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP) by angiotensin II (ANG II) and by ANG II in combination with either l -NAME, HOE 140 or minoxidil on the mean arterial blood pressure (MABP) and the noradrenaline sensitivity in isolated portal vein preparations. MABP was significantly increased by ANG II treatment and ANG II plus l -NAME. However, it was slightly affected by ANG II in association with HOE 140, and significantly lowered by ANG II plus minoxidil. In control animals noradrenaline increased the frequency and the tone of contractile force. While ANG II enhanced the contractile response to noradrenaline, neither in combination with l -NAME, HOE 140 nor minoxidil prevented such an increase in the response to noradrenaline. In the presence of ergotamine, the contractile response to noradrenaline was completely blocked not only in control animals, but also in animals treated with ANG II alone or in combination with minoxidil. However, ergotamine (3 microm) failed to block completely the contractile response to noradrenaline in vessels from animals treated by ANG II in combination with l -NAME or HOE 140. These data suggest that ANG II causes an increase of noradrenaline sensitivity in the isolated portal vein of rat. l -NAME and HOE 140 unmask a contractile response to noradrenaline in the presence of ergotamine which seems to be mediated not only by alpha-adrenoceptors, but may be compensated by an endothelial relaxation.

Hemolymph ion composition and volume changes in the supralittoral isopod Ligia pallasii Brandt, during molt

We analyzed ion composition and volume of the hemolymph of Ligia pallasii in four different stages of the molt cycle using capillary electrophoresis and 3H-inulin. The main ions in the hemolymph were Na+, K+, Mg2+ , Ca2+, and Cl-. The Ca2+ concentration increased significantly during the molt by 47% from intermolt to intramolt and by 37% from intermolt to postmolt, probably due to resorption of Ca2+ from the cuticle and sternal CaCO3 deposits. The K+ concentration increased significantly by 20% during molt. The hemolymph volume normalized to the dry mass of the animals decreased by 36% from intermolt to late premolt. This was due to a reduction in the hemolymph volume and to an increase in dry mass of the animals during premolt. A sudden increase in the hemolymph volume occurring between late premolt and intramolt served to expand the cuticle. Since the Na+, K+, Mg2+, and Cl- concentrations did not change significantly from late premolt to intramolt, the increase in hemolymph volume suggests an uptake of seawater rather than freshwater.

Influence of salmeterol and benzalkonium chloride on G-protein-mediated exocytotic responses of rat peritoneal mast cells

The long-acting beta(2)-adrenoceptor agonist salmeterol and the invert soap benzalkonium chloride share physicochemically important structures, namely a polar head group and a long aliphatic chain. Low concentrations of benzalkonium chloride have been shown to inhibit exocytotic responses in rat peritoneal mast cells by selectively interacting with heterotrimeric G-proteins of the G(i)-type. The present study investigates whether salmeterol inhibits, independently of beta-adrenoceptors, exocytotic responses of rat peritoneal mast cells induced by the direct agonists at G-proteins mastoparan or guanosine 5'-O-(3-thiotriphosphate) (++GTP gamma S++). Exocytosis was studied by secretion assays ([3H]5-hydroxytryptamine ([3H]5-HT)-release) using intact, streptolysin O-permeabilised or metabolically inhibited (antimycin, deoxyglucose) rat peritoneal mast cells. Both amphiphilics, salmeterol, and benzalkonium chloride, dose-dependently exerted biphasic effects on mastoparan-induced [3H]5-HT release in intact mast cells. In contrast to benzalkonium chloride, the dose-response curves for secretostatic and celltoxic effects of salmeterol markedly overlapped. Similar to benzalkonium chloride, salmeterol in non-cytotoxic concentrations (1-25 microg/ml) dose-dependently inhibited exocytosis induced by mastoparan (intact cells) or ++GTP gamma S (permeabilised cells). These findings indicate a direct, adrenoceptor-independent affection of G proteins by salmeterol in mast cells.

Surface expression of HLA-C antigen by human extravillous trophoblast

In this paper definitive evidence that the classical class I product, HLA-C, is expressed on the surface of normal trophoblast cells is provided. HLA-C transcripts were sequenced from cDNA isolated from first trimester trophoblast cells obtained by flow cytometric sorting. Both paternal and maternal alleles were transcribed. HLA-C proteins were demonstrated by biochemical analysis and found on the cell surface in association with beta(2)-microglobulin. Upregulation of cell surface HLA-C but not HLA-G expression after interferon (IFN)-gamma treatment was demonstrated by flow cytometric analysis. Immunohistology has confirmed HLA-C is expressed by all extravillous subpopulations in vivo. The question of whether trophoblast HLA-C molecules interact with decidual NK cells expressing killer Ig-like receptors (KIR) has also been addressed. Our results demonstrate that extravillous trophoblast expresses at least two HLA class I molecules, HLA-G and HLA-C on the cell surface.

Characterization of the major metabolites of verapamil as substrates and inhibitors of P-glycoprotein

Verapamil is subject to extensive oxidative metabolism mediated by cytochrome P450 enzymes with less than 5% of an oral dose being excreted unchanged in urine. Furthermore, verapamil is known to be a potent inhibitor of P-glycoprotein function. There is evidence from in vivo investigations that some verapamil metabolites might be actively transported. The aim of the present study was to investigate P-glycoprotein-mediated transport and inhibition properties of verapamil and its metabolites norverapamil, D-620, D-617, and D-703. Polarized transport of these compounds was assessed in P-glycoprotein-expressing Caco-2 and L-MDR1 cells (LLC-PK1 cells stably transfected with human MDR1-P-glycoprotein). Inhibition of P-glycoprotein-mediated transport by these compounds was determined using digoxin as P-glycoprotein substrate. At concentrations of 5 microM, significant differences between basal-to-apical and apical-to-basal apparent permeability coefficients were observed for D-617 and D-620 in all P-glycoprotein-expressing cell monolayers, indicating that both are P-glycoprotein substrates. In contrast, no P-glycoprotein-dependent transport was found for verapamil, norverapamil, and D-703 in Caco-2 cells and for D-703 in L-MDR1 cells. Moreover, verapamil, norverapamil, and D-703 inhibited P-glycoprotein-mediated digoxin transport with IC(50) values of 1.1, 0.3, and 1.6 microM, respectively, whereas D-617 and D-620 did not (at concentrations up to 100 microM). We conclude that verapamil phase I metabolites exhibit different P-glycoprotein substrate and inhibition characteristics, with the N-dealkylated metabolites D-617 and D-620 being P-glycoprotein substrates and norverapamil and D-703 being inhibitors of P-glycoprotein function, which may influence P-glycoprotein-dependent drug disposition and elimination.

Peptide mapping and characterisation of glycation patterns of the glima 38 antigen recognised by autoantibodies in Type I diabetic patients

AIMS/HYPOTHESIS

Glima 38 is an N-glycated neuroendocrine membrane protein of M(r) 38,000, which is recognised by autoantibodies in approximately 20% of patients with Type I (insulin-dependent) diabetes mellitus. The aim of this study was to characterise the carbohydrate moiety and generate peptide maps of glima 38.

METHODS

Sera of high immunoreactivity to glima 38 were used to isolate 35-S methionine-labelled protein from betaTC-3 cells and a neuronal cell line GT1.7. Tunicamycin was used to inhibit N-glycation of glima 38 and define the core protein. The carbohydrate moiety was characterised for tunicamycin sensitivity, lectin binding and susceptibility to different endoglycosidases. The protein moiety was subjected to digestion by proteases to define peptide maps.

RESULTS

The autoreactive epitopes in glima 38 recognised by Type I diabetic sera are conformational and independent of the carbohydrate moiety. Inhibition of N-glycation of glima 38 in vivo, shows a protein core of M(r) 22,000 in both pancreatic beta-(betaTC3) and neuronal (GT1.7) cell lines. The carbohydrate moieties in the two cell types are distinct but contain a similar amount of terminal sialic acid residues and at least five oligosaccharide chains Glima 38 binds Triticum vulgare and Ricinus communis I lectins. Endoproteinase treatment of the M(r) 22,000 core protein results in peptides of M(r) 4500 and M(r) 20,000 with Lys-C, and peptides of M(r) 4000 and M(r) 11,000-12,000 with Glu-C/V8 and Asp-N proteases.

CONCLUSION/INTERPRETATION

The biochemical properties of glima 38 define it as a new autoantigen in Type I diabetes and provide a basis for its purification.

Aphid transmission studies using helper component proteins of potato virus Y expressed from a vector derived from potato virus X

The genes encoding the helper component (HC) proteins of two strains of Potato virus Y (PVY) were cloned and the proteins expressed from a vector derived from Potato virus X (PVX). The expressed HC contained six N-terminal histidine residues to facilitate purification by metal affinity chromatography. Approximately 2-4 microg/g of purified HC was obtained from leaves of Nicotiana benthamiana plants systemically infected by recombinant PVX. Preparations of the HC protein derived from PVY ordinary strain (PVY(o)) assisted aphid transmission of purified particles of PVY(o) and PVY strain C (PVY(c); a naturally occurring non-aphid transmissible strain of PVY which contains a defective HC), as well as Potato aucuba mosaic virus. The HC derived from PVY(c) contained the Glu-Ile-Thr-Cys (EITC) motif, and mutation of Glu (E) to Lys (K) enabled the mutant PVX-expressed preparations to assist virus transmission by aphids. Expression of HC protein from the PVX vector produced biologically active protein. This approach should facilitate further studies to elucidate more precisely the molecular mechanism of virus transmission by aphids.