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Biomedical subjects

M Brantly

Publications and source records attributed to M Brantly.

At least 19 recordsLinked to original sources

Pulmonary dysfunction in adults with nephropathic cystinosis.

OBJECTIVE: To characterize the pulmonary dysfunction in patients with nephropathic cystinosis after renal transplantation. DESIGN: Cross-sectional analysis of consecutive adult patients. PATIENTS: Twelve adult, nephropathic cystinosis patients and 3 adult, ocular, nonnephropathic cystinosis patients admitted to the National Institutes of Health Clinical Center. RESULTS: The 12 nephropathic cystinosis patients (age range, 21 to 40 years) showed an extraparenchymal pattern of restrictive lung disease, with inspiratory and expiratory dysfunction. Specifically, the mean FVC was 58% of predicted, the mean FEV(1) was 57% of predicted, and the mean total lung capacity was 66% of predicted, while the mean residual volume was normal. Furthermore, the mean maximal inspiratory pressure for the eight patients tested was 40% of predicted, and the mean maximal expiratory pressure was 26% of predicted. Two patients died of respiratory insufficiency. All the patients had lived at least 17 years, while lacking compliant cystine-depleting therapy with oral cysteamine. Seven patients had a conical chest, restricting excursion, and 10 of the 12 patients had evidence of the myopathy that typifies late cystinosis. In fact, the severity of pulmonary disease correlated directly with the severity of myopathy in our group of 12 patients. In contrast, the lung parenchyma was essentially normal, as gauged by chest radiographs and CT scans of the lung. The three patients with nonnephropathic cystinosis displayed entirely normal pulmonary function. CONCLUSION: The distal myopathy characteristic of nephropathic cystinosis results in an extraparenchymal pattern of restrictive lung disease in adults who have not received long-term cystine depletion. Whether or not oral cysteamine therapy can prevent this complication remains to be determined.

Adult↗

Inhibition of recombinant adeno-associated virus (rAAV) transduction by bronchial secretions from cystic fibrosis patients.

The conducting airways are the primary target for gene transfer in cystic fibrosis (CF), yet the inflammation associated with CF lung disease could potentially pose a significant barrier to gene transfer vectors, such as recombinant adeno-associated virus (rAAV). In order to investigate this possibility, aliquots of bronchoalveolar lavage (BAL) fluid from eight individuals with CF were tested for their in vitro inhibitory effects on rAAV transduction, along with BAL from non-CF individuals. While the non-CF BAL fluid was not inhibitory, seven of eight CF BAL samples had significant inhibitory activity, resulting in a five- to 20-fold reduction in transduction events. Inhibition of rAAV transduction by CF BAL could be reversed by alpha-1-antitrypsin (AAT), but not by DNase. When neutrophil elastase and neutrophil alpha defensins (human neutrophil peptides, HNP) were measured in these samples, they were elevated by 500- and 10,000-fold, respectively. The levels of HNP correlated inversely with the amount of rAAV transduction. Furthermore, rAAV transduction could be blocked by purified HNP in an AAT-reversible manner at HNP concentrations within the range measured in these fluids. We conclude that products of inflammation in CF BAL fluid are inhibitory to rAAV transduction, and that these effects may be reversible by AAT.

Adolescent↗

Molecular mechanisms of alpha1-antitrypsin null alleles.

Alpha1-antitrypsin (alpha1-AT) is the most abundant circulating inhibitor of serine proteases and therefore is essential to normal protease-anti-protease homeostasis. Inheritance of two parental alpha1-AT deficiency alleles is associated with a substantially increased risk for development of emphysema and liver disease. In very rare circumstances individuals may inherit alpha1-AT null alleles. Null alpha1-AT alleles are characterized by the total absence of serum alpha1-AT. These alleles represent the extreme end in a continuum of alleles associated with alpha1-AT deficiency. The molecular mechanisms responsible for absence of serum alpha1-AT include splicing abnormalities, deletion of alpha1-AT coding exons and premature stop codons. While these alleles comprise only a small proportion of alpha1-AT alleles associated with profound alpha1-AT deficiency, studies of their molecular mechanisms provide valuable insights into the structure, gene expression and intracellular transport of alpha1-AT.

Alleles↗

Pulmonary function and high-resolution CT findings in patients with an inherited form of pulmonary fibrosis, Hermansky-Pudlak syndrome, due to mutations in HPS-1.

OBJECTIVE: To describe and correlate pulmonary function and high-resolution CT (HRCT) scan scores in individuals with a high risk for development of pulmonary fibrosis, ie, Hermansky-Pudlak syndrome (HPS) patients with mutations in the HPS-1 gene. DESIGN: Cross-sectional analysis of consecutive, eligible patients. PATIENTS: Thirty-eight HPS inpatients at the National Institutes of Health Clinical Center with HPS-1 mutations. RESULTS: Thirty-seven patients were Puerto Rican and exhibited the typical 16-base pair (bp) duplication in exon 15 of HPS-1. One non-Puerto Rican was homozygous for a different mutation (intervening sequence 17 -2 A-->C) previously reported in the HPS-1 gene; he died at age 35 of pulmonary insufficiency. For the 23 patients who had pulmonary symptoms, the mean age of onset was 35 years. For all 38 patients (mean age, 37 +/- 2 years), the mean FVC was 71% of predicted; the mean FEV(1), 76%; mean total lung capacity (TLC), 72%; mean vital capacity (VC), 68%; and mean diffusing capacity of the lung for carbon monoxide (DLCO), 72%. When patients were grouped according to the extent of their reduction in FVC, the other four pulmonary function parameters followed the FVC. Seventeen patients had abnormal chest radiographs, and 31 (82%) had abnormal HRCT scans of the chest, for which a scoring system of 0 (normal) to 3 (severe fibrosis) is presented. The mean +/- SEM HRCT score for 38 patients was 1.30 +/- 0.17. HRCT scores correlated inversely with FVC and DLCO. CONCLUSIONS: Mutations in the HPS-1 gene, whether or not they involve the typical 16-bp duplication seen in Puerto Rican patients, are associated with fatal pulmonary fibrosis. In affected patients, the FVC, FEV(1), TLC, VC, and DLCO fall in concert, and this functional deficit correlates with HRCT scan evidence of progression of interstitial lung disease.

Adult↗

Formation and current results of a patient-organized registry for alpha(1)-antitrypsin deficiency.

BACKGROUND: Significant challenges exist to investigating uncommon illnesses because too few patients are seen at any single clinical center to permit appropriate research studies. Recognizing this impediment to clinical research in alpha(1)-antitrypsin deficiency, the Alpha One Foundation, a patient-organized research foundation, has collaborated with clinician-scientists to organize a voluntary registry of individuals with alpha(1)-antitrypsin deficiency. PURPOSE: To facilitate clinical research in alpha(1)-antitrypsin deficiency by organizing a registry of affected individuals willing to be approached to participate in clinical studies. METHODS: Elements of the Alpha One Foundation Research Network Registry include a Medical and Scientific Advisory Committee, composed of physician-investigators and patient advocates, designated clinical resource centers at medical institutions with expertise in the management of individuals with alpha(1)-antitrypsin deficiency, and a data coordinating center with responsibility for database management and analysis. Questionnaires requesting information about demographic features, alpha(1)-antitrypsin phenotype, smoking history, and health-care utilization were distributed to prospective registrants through the following channels: mailings from the Alpha One Foundation; mailings from the clinical resource centers; and distribution by home-care and pharmaceutical companies. Information from this questionnaire formed the basis of the initial registry database. RESULTS: Between May 1997 and June 1999, 7,789 forms were distributed, and forms were returned by 712 unique registrants. Registrants have the following characteristics: mean (+/- SD) age, 49.3+/-13.2 years; women, 47.7%; white, 96.2%; PI*ZZ phenotype, 70.7%; ex-smokers, 73.3%; COPD patients, 87.2% (emphysema patients, 54.2%; chronic bronchitis patients, 33%); and self-reported liver disease, 6.4%. The mean number of physician visits reported by registrants in the preceding 12 months was 7.8+/-9.4, 59% reported currently receiving IV augmentation therapy, and 35% reported using supplemental oxygen at home. Examples of ongoing research studies using this unique database include: (1) a case-control study to evaluate occupational risk factors for obstructive lung disease in individuals with alpha(1)-antitrypsin deficiency and (2) a study to evaluate the health-care costs for affected individuals. CONCLUSIONS: A registry currently including 712 individuals with alpha(1)-antitrypsin deficiency has been organized through a collaboration between physician-investigators and a patient-organized research foundation. Use of the registry has already facilitated studies that were previously difficult because of the paucity of identifiable study subjects. The registry cohort promises to provide an important resource for future clinical and epidemiologic studies.

Clinical Trials as Topic↗

Efficient in vivo catheter-based pericardial gene transfer mediated by adenoviral vectors.

Adenoviral vectors are promising agents for a number of in vivo gene therapy applications including diseases of the heart and coronary vessels. Efficient intravascular gene transfer to specific sites has been achieved in occluded vessels, but otherwise is hampered by the effect of blood flow on localized vector uptake in the vessel wall. An alternative delivery approach to coronary arteries is the expression of diffusible gene products into the pericardial space surrounding the heart and coronary arteries. However, in vivo pericardial access is comparatively difficult and has been limited to surgical approaches. We hypothesized that efficient adenovirus-mediated gene expression in pericardial lining mesothelium could be achieved by transmyocardial vector delivery to the pericardium. To evaluate this concept, a hollow, helical-tipped penetrating catheter was used to deliver vector-containing fluid directly into the intrapericardial space. The catheter was introduced percutaneously in anesthetized mongrel dogs, advanced into the right ventricle, and the tip passed through the apical right ventricular myocardium under direct radiographic visualization until the open end of the catheter tip resided in the intrapericardial space. Adenoviral vectors expressing either nuclear-localizing beta-galactosidase, cytoplasmic luciferase, or secreted human alpha 1AT reporters (Av1nBg, Av1Lu, or Av1Aa, respectively) were instilled through the catheter into the intrapericardial space. Three days later the animals were sacrificed and reporter gene expression was evaluated in pericardium, epicardium, and multiple other tissues. In animals receiving Av1nBg, beta-galactosidase activity was evident in most of the pericardial lining endothelium, up to 100% in many areas. In animals receiving Av1Lu, luciferase reporter activity was abundant in pericardial tissues, but near-background levels were observed in other organs. In animals receiving Av1Aa, human alpha 1AT was abundant (16-29 mg/ml) in pericardial fluid, but was undetectable in serum. All animals tolerated the procedure well with no electrocardiographic changes and no clinical sequelae. These observations demonstrate highly efficient adenovirus vector delivery and gene transfer and expression in the pericardium and support the feasibility of localized gene therapy via catheter-based pericardial approaches. We suggest that the pericardial sac may serve as a sustained-release protein delivery system for the generation of desired gene products or their metabolites for diffusion into the epicardial region.

Adenoviridae↗

Sustained secretion of human alpha-1-antitrypsin from murine muscle transduced with adeno-associated virus vectors.

Recombinant adeno-associated virus (AAV) vectors have been used to transduce murine skeletal muscle as a platform for secretion of therapeutic proteins. The utility of this approach for treating alpha-1-antitrypsin (AAT) deficiency was tested in murine myocytes in vitro and in vivo. AAV vectors expressing the human AAT gene from either the cytomegalovirus (CMV) promoter (AAV-C-AT) or the human elongation factor 1-alpha promoter (AAV-E-AT) were examined. In vitro in C2C12 murine myoblasts, the expression levels in transient transfections were similar between the two vectors. One month after transduction, however, the human elongation factor 1 promoter mediated 10-fold higher stable human AAT expression than the CMV promoter. In vivo transduction was performed by injecting doses of up to 1.4 x 10(13) particles into skeletal muscles of several mouse strains (C57BL/6, BALB/c, and SCID). In vivo, the CMV vector mediated higher levels of expression, with sustained serum levels over 800 micrograms/ml in SCID and over 400 micrograms/ml in C57BL/6 mice. These serum concentrations are 100,000-fold higher than those previously observed with AAV vectors in muscle and are at levels which would be therapeutic if achieved in humans. High level expression was delayed for several weeks but was sustained for over 15 wk. Immune responses were dependent upon the mouse strain and the vector dosage. These data suggest that recombinant AAV vector transduction of skeletal muscle could provide a means for replacing AAT or other essential serum proteins but that immune responses may be elicited under certain conditions.

Animals↗

Inhibition of intracellular degradation increases secretion of a mutant form of alpha1-antitrypsin associated with profound deficiency.

The mutant Z form of alpha1-antitrypsin (alpha1AT) is responsible for > 95% of all individuals with alpha1AT deficiency, an important inherited cause of emphysema and liver disease. Since secreted Z alpha1AT is a functional antiprotease, we hypothesized that interrupting catabolism of retained Z alpha1AT might increase its transport out of cells, causing an increase in extracellular protease protection. Both the protein translation inhibitor cycloheximide and the specific inhibitor of proteasome function, lactacystin, prevented intracellular degradation of Z alpha1AT. Moreover, this inhibition of degradation was associated with partial restoration of Z alpha1AT vesicular transport. This effect was observed in a model system of transfected CHO cells as well as in human alveolar macrophages synthesizing Z alpha1AT. This study supports the hypothesis that altering the intracellular fate of a mutant protein may be an option in the treatment of diseases associated with misfolded but potentially functional proteins.

Animals↗

Genetic defects and clinical characteristics of patients with a form of oculocutaneous albinism (Hermansky-Pudlak syndrome).

BACKGROUND: Hermansky-Pudlak syndrome is characterized by oculocutaneous albinism, a storage-pool deficiency, and lysosomal accumulation of ceroid lipofuscin, which causes pulmonary fibrosis and granulomatous colitis in some cases. All identified affected patients in northwest Puerto Rico are homozygous for a 16-bp duplication in exon 15 of a recently cloned gene, HPS. We compared the clinical and laboratory characteristics of these patients with those of patients without the 16-bp duplication. METHODS: Forty-nine patients -- 27 Puerto Ricans and 22 patients from the mainland United States who were not of Puerto Rican descent -- were given a diagnosis on the basis of albinism and the absence of platelet dense bodies. We used the polymerase chain reaction to determine which patients carried the 16-bp duplication. RESULTS: Twenty-five of the Puerto Rican patients were homozygous for the 16-bp duplication, whereas none of the non-Puerto Rican patients carried this mutation. Like the patients without the duplication, the patients with the 16-bp duplication had a broad variation in pigmentation. Nine of 16 adults with the duplication, but none of the 10 without it, had a diffusing capacity for carbon monoxide that was less than 80 percent of the predicted value. High-resolution computed tomography in 12 patients with the 16-bp duplication revealed minimal fibrosis in 8, moderate fibrosis in 1, severe fibrosis in 1, and no fibrosis in 2. Computed tomography in eight patients without the duplication revealed minimal fibrosis in three and no fibrosis in the rest. Inflammatory bowel disease developed in eight patients (four in each group) between 3 and 25 years of age. CONCLUSIONS: The 16-bp duplication in exon 15 of HPS, which we found only in Puerto Rican patients, is associated with a broad range of pigmentation and an increased risk of restrictive lung disease in adults.

Adolescent↗

Alpha 1-antitrypsin nonsense mutation associated with a retained truncated protein and reduced mRNA.

alpha 1-Antitrypsin (alpha 1AT) provides the major protection in the lung against neutrophil elastase-mediated proteolysis. Inheritance of alpha 1AT deficiency alleles is associated with an increased risk of emphysema and liver disease. alpha 1AT null alleles cause the total absence of serum alpha 1AT and represent the ultimate in a continuum of alleles associated with alpha 1AT deficiency. The molecular mechanisms responsible for absence of serum alpha 1AT include splicing abnormalities, deletion of alpha 1AT coding exons, and premature stop codons. We identified an Italian individual with asthma, emphysema, and a very low level of serum alpha 1AT. DNA sequencing demonstrated the Mprocida deficiency allele and a novel null allele, QOtrastevere (c654 G-->A, W194Z), a nonsense mutation near the intron 2 (IVS2) splice acceptor site. To determine the molecular basis of QOtrastevere and specifically to evaluate whether this nonsense mutation interfered with mRNA processing by altered splicing, we used a Chinese hamster ovary cell line permanently transfected with QOtrastevere or normal M alpha 1AT with and without IVS2. Northern blot analysis demonstrated that the normal M construct, with or without IVS2, expressed alpha 1AT mRNA of a similar size. The nonsense mutation was associated with moderately reduced alpha 1AT mRNA regardless of the presence or absence of IVS2. Reduction in alpha 1AT mRNA regardless of the opportunity for splicing supports a translational-translocation model as the cause of reduced alpha 1AT mRNA rather than the nuclear scanning model. Pulse-chase studies followed by immunoprecipitation demonstrated an endoplasmic reticulum-retained 31 kDa QOtrastevere alpha 1AT, which was rapidly degraded. Although mRNA content was moderately reduced, retention and rapid intracellular degradation of the truncated form are the major mechanisms for the absence of secreted alpha 1AT.

Alleles↗

Rapid development of hepatic alpha1-antitrypsin globules after liver transplantation for chronic hepatitis C.

A 37-year-old man undergoing liver transplantation for cirrhosis caused by chronic hepatitis C and alcoholism developed large numbers of alpha1-antitrypsin (AAT) globules within hepatocytes of the transplanted liver during a 5-month period. This finding occurred simultaneously with severe recurrent hepatitis C. The AAT phenotype of this patient changed from MM before transplantation to MZ after transplantation; AAT levels in serum did not change significantly. After a second liver transplantation 6 months after the first, the AAT phenotype reverted to MM and globules were not detectable in the second transplanted liver. Severe recurrent hepatitis C and the appearance of AAT globules within the liver allograft of a heterozygous donor may be related. The recurrent infection may have induced accumulation of AAT protein, or, alternatively, the MZ liver may have been more susceptible to injury from recurrent viral infection.

Adult↗

alpha1-antitrypsin gene mutation hot spot associated with the formation of a retained and degraded null variant [corrected; erratum to be published].

Null alpha1-antitrypsin (alpha1AT) alleles represent the end of a continuum of variants associated with profound alpha1AT deficiency and an increased risk of emphysema. This study characterizes the molecular basis of QOclayton, a new example of an alpha1AT null allele arising from a mutational hot spot in the alpha1AT gene. The QOclayton allele is identical to the normal M1(V213) alpha1AT allele except for an insertion of a cytosine. This insertion occurs in the alpha1AT sequence which normally has seven cytosines corresponding to amino acid residues 360 to 362. The QOclayton mutation is located in the same reiterated DNA sequence as the alpha1AT QObolton deletion mutation and the insertion mutation allele QOsaarbruecken. The QOclayton cytosine insertion causes a 3' frameshift and results in the formation of a termination codon at residue 376, the same consequence as the alpha1AT QOmattawa mutation (L353 T-insertion with a 3' frameshift). To determine the molecular mechanisms responsible for the absence of alpha1AT associated with the QOclayton gene, an in vitro model of QOclayton was established using Chinese hamster ovary cells (CHO) transfected with the QOclayton gene. These cells were evaluated for alpha1AT mRNA expression, protein synthesis and secretion. Although the QOclayton gene expresses a similar amount of alpha1AT mRNA as compared with the normal alpha1AT gene, no QOclayton protein is secreted. Protein trafficking and double-label immunofluorescence demonstrate that the QOclayton protein is retained in the rough endoplasmic reticulum or pre-Golgi compartment and is degraded (t1/2 = 6.5 h). Since QOmattawa, QObolton, and QOsaarbruecken have similar termination sites in the alpha1AT mRNA, they may share a similar intracellular fate.

Animals↗

Hepatocytes corrected by gene therapy are selected in vivo in a murine model of hereditary tyrosinaemia type I.

Current strategies for hepatic gene therapy are either quantitatively inefficient or suffer from lack of permanent gene expression. We have utilized an animal model of hereditary tyrosinaemia type I (HT1), a recessive liver disease caused by deficiency of fumarylacetoacetate hydrolase (FAH), to determine whether in vivo selection of corrected hepatocytes could improve the efficiency of liver gene transfer. As few as 1,000 transplanted wild-type hepatocytes were able to repopulate mutant liver, demonstrating their strong competitive growth advantage. Mutant hepatocytes corrected in situ by retroviral gene transfer were also positively selected. In mutant animals treated by multiple retrovirus injections >90% of hepatocytes became FAH positive and liver function was restored to normal. Our results demonstrate that in vivo selection is a useful strategy for hepatic gene therapy and may lead to effective treatment of human HT1 by retroviral gene transfer.

Amino Acid Metabolism, Inborn Errors↗

Heterozygosity for an exon 12 splicing mutation and a W234G missense mutation in an American child with chronic tyrosinemia type 1.

Hereditary tyrosinemia type 1, an autosomal recessive disorder caused by deficiency of fumarylace-toacetate hydrolase (FAH), manifests in either an acute or a chronic form. We used reverse transcription and the polymerase chain reaction to amplify the FAH cDNA of a 12-year-old American boy with chronic tyrosinemia type 1. The patient is a compound heterozygote for mutations in the FAH gene. One allele contains a missense mutation in codon 234 changing a tryptophan to a glycine; this allele was of maternal origin. Mutagenesis and transfection into COS cells demonstrated that the W234G mutation abolishes FAH activity. The patient's paternally derived allele is a splicing mutation in the +5 position of intron 12, causing either insertion of a 105 bp fragment due to a cryptic splice site, or skipping of exon 12, or skipping of both exons 12 and 13. The chronic phenotype of tyrosinemia type 1 in this patient may be due to some residual, correct splicing by the allele with the splicing mutation.

Amino Acid Metabolism, Inborn Errors↗

Is rotavirus a population of reassortants?

Rotaviruses appear to exist as heterogeneous populations of reassortants and related variants. This phenomenon is consistent with the quasispecies concept of RNA viruses, and suggests that gene reassortment is a crucial evolutionary mechanism for this segmented virus. It also explains puzzling epidemiological findings and controversial results of vaccine-efficacy studies.

Animals↗

Abnormal synthesis of dolichol-linked oligosaccharides in carbohydrate-deficient glycoprotein syndrome.

Carbohydrate-deficient glycoprotein syndrome (CDGS) is a rare metabolic disorder presenting in infancy with severe neurologic involvement and variable multisystemic abnormalities. Diagnosis relies upon the detection of abnormal serum glycoprotein isoforms on isoelectric focusing (IEF) gels. Carbohydrate structural analyses were performed on the N-linked oligosaccharides of serum alpha 1-antitrypsin (alpha-1AT) from two Danish children with classical type I CDGS. Following preparative gel electrophoresis of alpha-1AT isoforms, oligosaccharide charge and monosaccharide composition analyses revealed increased glycosylation heterogeneity in CDGS compared with normal alpha-1AT. CDGS alpha-1AT isoforms bore N-glycans co-migrating with monosialylated standards, while normal alpha-1AT oligosaccharides co-migrated with both mono- and disialylated standards. While the monosaccharide contents of normal alpha-1AT isoforms were relatively uniform, those of CDGS alpha-1AT isoforms varied widely, and many were relatively mannose enriched. The mannose-rich oligosaccharides of CDGS alpha-1AT were not typical oligomannose structures since they were not released by endo-beta-N-acetylglucosaminidase H (endo H) digestion. Metabolic labelling of CDGS fibroblasts with [3H]mannose showed lower than normal intracellular total mannose, free mannose and phosphorylated mannose species, as well as diminished [3H]mannose incorporation into dolichol-linked and protein-linked oligosaccharides. In addition, the glycans liberated from CDGS dolichol-linked oligosaccharides were significantly truncated compared with those from normal fibroblasts. These data suggest that our type I CDGS patients produce abnormal N-linked oligosaccharides due to impaired biosynthesis of dolichol-oligosaccharide precursors.

Congenital Disorders of Glycosylation↗

Clinical features and molecular characteristics of alpha 1-antitrypsin deficiency.

Alpha-1-antitrypsin deficiency is a common, underrecognized disorder manifested by emphysema in adults and liver disease in children. Early diagnosis and subsequent prevention of lung inflammation due to cigarette smoking, infection, and airborne irritants form the most rational approach to slow the progression of the lung destruction associated with alpha 1AT deficiency. Currently, liver transplantation is the only therapy available to patients with severe liver disease due to alpha 1AT deficiency. Less commonly, many inflammatory and/or immune-mediated diseases have been described in association with alpha 1AT deficiency. These observations are probably related to the role that alpha 1AT plays in the immune response both as a target for modulation by cytokines and as a modulator of the immune response. At present, therapy for the emphysema associated with alpha 1AT is limited to weekly augmentation therapy with recombinant alpha 1AT. Future therapeutic modalities include aerosol alpha 1AT, secretory leukocyte proteinase inhibitor, low molecular weight inhibitors of neutrophil elastase, and gene transfer via viral vector.

Base Sequence↗