Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “gene expression variability”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

A SAGE (serial analysis of gene expression) view of breast tumor progression.

To identify molecular alterations involved in the initiation and progression of breast carcinomas, we analyzed the global gene expression profiles of normal mammary epithelial cells and in situ, invasive, and metastatic breast carcinomas using serial analysis of gene expression (SAGE). We identified sets of genes expressed only or most abundantly in a specific stage of breast tumorigenesis or in a certain subtype of tumors through the pair-wise comparison and by hierarchical clustering analysis of these eight SAGE libraries (two/stage). On the basis of these comparisons, we made the following observations: Normal mammary epithelial cells showed the most distinct and least variable gene expression profiles. Many of the genes highly expressed in normal mammary epithelium and lost in carcinomas encoded secreted proteins, cytokines, and chemokines, implicating abnormal paracrine and autocrine signaling in the initiation of breast tumorigenesis. Very few genes were universally up-regulated in all tumors regardless of their stage and histological grade, indicating a high degree of diversity at the molecular level that likely reflects the clinical heterogeneity characteristic of breast carcinomas. Tumors of different histology type and stage had very distinct gene expression patterns. No genes seemed to be specific for metastatic or for in situ carcinomas. We found that the most dramatic and consistent phenotypic change occurred at the normal-to-in situ carcinoma transition. This observation, combined with the fact that many of the genes involved encode secreted, cell-nonautonomous factors, implies that the normal epithelium-to-in situ carcinoma transition may be the most promising target for cancer prevention and treatment.

Adult↗

Recreational music-making modulates the human stress response: a preliminary individualized gene expression strategy.

BACKGROUND: A central component of the complex human biological stress response is the modulation of the neuro-endocrine-immune system with its intricate feedback loops that support homeostatic regulation. Well-documented marked gene expression variability among human and animal subjects coupled with sample collection timing and delayed effects, as well as a host of molecular detection challenges renders the quest for deciphering the human biological stress response challenging from many perspectives. MATERIAL/METHODS: A novel Recreational Music-Making (RMM) program was used in combination with a new strategy for peripheral blood gene expression analysis to assess individualized genomic stress induction signatures. The expression of 45 immune response-related genes was determined using a multiplex preamplification step prior to conventional quantitative Real Time Polymerase Chain Reaction (qRT-PCR) mRNA analysis to characterize the multidimensional biological impact of a 2-phase controlled stress induction/amelioration experimental protocol in 32 randomly assigned individuals. RESULTS: In subjects performing the RMM activity following a 1-hour stress induction protocol, 19 out of 45 markers demonstrated reversal with significant (P = 0.05) Pearson correlations in contrast to 6 out of 45 markers in the resting control group and 0 out of 45 in the ongoing stressor group. CONCLUSIONS: The resultant amelioration of stress-induced genomic expression supports the underlying premise that RMM warrants additional consideration as a rational choice within our armamentarium of stress reduction strategies. Modulation of individualized genomic stress induction signatures in peripheral blood presents a new opportunity for elucidating the dynamics of the human stress response.

Adolescent↗

Assessment of a systematic expression profiling approach in ENU-induced mouse mutant lines.

Comparative genomewide expression profiling is a powerful tool in the effort to annotate the mouse genome with biological function. The systematic analysis of RNA expression data of mouse lines from the Munich ENU mutagenesis screen might support the understanding of the molecular biology of such mutants and provide new insights into mammalian gene function. In a direct comparison of DNA microarray experiments of individual versus pooled RNA samples of organs from ENU-induced mouse mutants, we provide evidence that individual RNA samples may outperform pools in some aspects. Genes with high biological variability in their expression levels (noisy genes) are identified as false positives in pooled samples. Evidence suggests that highly stringent housing conditions and standardized procedures for the isolation of organs significantly reduce biological variability in gene expression profiling experiments. Data on wild-type individuals demonstrate the positive effect of controlling variables such as social status, food intake before organ sampling, and stress with regard to reproducibility of gene expression patterns. Analyses of several organs from various ENU-induced mutant lines in general show low numbers of differentially expressed genes. We demonstrate the feasibility to detect transcriptionally affected organs employing RNA expression profiling as a tool for molecular phenotyping.

Animals↗

Transcriptional noise and cellular heterogeneity in mammalian macrophages.

Transcriptional noise is known to play a crucial role in heterogeneity in bacteria and yeast. Mammalian macrophages are known to exhibit cell-to-cell variation in their responses to pathogens, but the source of this heterogeneity is not known. We have developed a detailed stochastic model of gene expression that takes into account scaling effects due to cell size and genome complexity. We report the results of applying this model to simulating gene expression variability in mammalian macrophages, demonstrating a possible molecular basis for heterogeneity in macrophage signalling responses. We note that the nature of predicted transcriptional noise in macrophages is different from that in yeast and bacteria. Some molecular interactions in yeast and bacteria are thought to have evolved to minimize the effects of the high-frequency noise observed in these species. Transcriptional noise in macrophages results in slow changes to gene expression levels and would not require the type of spike-filtering circuits observed in yeast and bacteria.

Animals↗

The structure of human lupus anti-DNA antibodies.

B-cell hyperactivity and production of pathogenic autoantibodies are the main immunological events in the pathogenesis of the human autoimmune disease systemic lupus erythematosus. One approach to studying the pathogenesis of this disease and to understanding how the autoantibody response is initiated and sustained has been to analyze the variable genes expressed by antibodies that have the hallmarks of the disease-causing subset of pathogenic autoantibodies. Such studies have provided important clues. Quantitation of this repertoire revealed the presence of a specific expansion of IgG clonotypes that impart reactivity with disease-related autoantigens. The sequences of the genes encoding autoantibodies derived from these patients and expressing nephritogenic idiotopes (present in immune complexes and renal eluates of subjects with active disease) show features of molecular diversification with a high rate of replacement/silent mutations and clustering of the mutations in the hypervariable regions. These characteristics imply that a pure polyclonal B-cell activation process cannot be the only mechanism responsible for autoantibody production. More likely, an antigen drive plays a role in generation of pathogenic autoantibodies. Based on additional studies of their light chain variable region genes, we have offered a novel genetically based model whereby B cells secreting pathogenic lupus autoantibodies are blocked in their capacity to turn off their autoreactivity and to acquire a new specificity, a mechanism called receptor editing. Studies of the molecular events involved in this mechanism and of the clonal fates of B cells in vivo will be important for future research.

Amino Acids↗

Individual variation of adipose gene expression and identification of covariated genes by cDNA microarrays.

Gene expression profiling through the application of microarrays provides comprehensive assessment of gene expression levels in a given tissue or cell population, as well as information on changes of gene expression in altered physiological or pathological situations. Microarrays are particularly suited to study interactions in the regulation of large numbers of different genes, since their expression is analyzed simultaneously. For improved understanding of the physiology of adipose tissue, and consequently obesity and diabetes, identification of covariability in gene expression was attempted by analysis of the individual variability of gene expression in subcutaneous white and brown fat of the Siberian dwarf hamster using microarrays containing approximately 300 cDNA fragments of adipose genes. No sex-dependant variability in gene expression could be found, and overall individual variability was rather low, with more than 80% of clones showing a coefficient of variation lower than 30%. Uncoupling protein 1 (UCP1) displayed a high variability of gene expression in brown fat, which was negatively correlated with the gene expression of complement factor B (FactB), implying a possible functional relationship.

Adipocytes↗

Human lung project: evaluating variance of gene expression in the human lung.

Nondiseased tissue is an important reference for microarray studies of pulmonary disease. We obtained 23 single lungs from multiorgan donors at time of procurement. Donors varied in age, sex, smoking history, and ethnicity. Lungs were dissected into upper and lower lobe peripheral sections for RNA extraction. Microarray analysis was performed using Affymetrix Hu-133 Plus 2.0 arrays. We observed that the relative variability of gene expression increased rapidly from technical (lowest), to regional, to population (highest). In addition, age and sex have measurable effects on gene expression. Gene expression variability is heterogeneously distributed among biologic categories. We conclude that gene expression variability is greater between individuals than within individuals and that population variability is the most important factor in the study design of microarray experiments of the human lung. Classes of genes with high population variability are biologically important and provide a novel perspective into lung physiology and pathobiology. Our study represents the first comprehensive analysis of nondiseased lung tissue. The generation of this robust dataset has important implications for the design and implementation of future comparative expression analysis with pulmonary disease states.

Adult↗

Gene expression profile of papillary thyroid cancer: sources of variability and diagnostic implications.

The study looked for an optimal set of genes differentiating between papillary thyroid cancer (PTC) and normal thyroid tissue and assessed the sources of variability in gene expression profiles. The analysis was done by oligonucleotide microarrays (GeneChip HG-U133A) in 50 tissue samples taken intraoperatively from 33 patients (23 PTC patients and 10 patients with other thyroid disease). In the initial group of 16 PTC and 16 normal samples, we assessed the sources of variability in the gene expression profile by singular value decomposition which specified three major patterns of variability. The first and the most distinct mode grouped transcripts differentiating between tumor and normal tissues. Two consecutive modes contained a large proportion of immunity-related genes. To generate a multigene classifier for tumor-normal difference, we used support vector machines-based technique (recursive feature replacement). It included the following 19 genes: DPP4, GJB3, ST14, SERPINA1, LRP4, MET, EVA1, SPUVE, LGALS3, HBB, MKRN2, MRC2, IGSF1, KIAA0830, RXRG, P4HA2, CDH3, IL13RA1, and MTMR4, and correctly discriminated 17 of 18 additional PTC/normal thyroid samples and all 16 samples published in a previous microarray study. Selected novel genes (LRP4, EVA1, TMPRSS4, QPCT, and SLC34A2) were confirmed by Q-PCR. Our results prove that the gene expression signal of PTC is easily detectable even when cancer cells do not prevail over tumor stroma. We indicate and separate the confounding variability related to the immune response. Finally, we propose a potent molecular classifier able to discriminate between PTC and nonmalignant thyroid in more than 90% of investigated samples.

Adolescent↗

Phase and antigenic variation in bacteria.

Phase and antigenic variation result in a heterogenic phenotype of a clonal bacterial population, in which individual cells either express the phase-variable protein(s) or not, or express one of multiple antigenic forms of the protein, respectively. This form of regulation has been identified mainly, but by no means exclusively, for a wide variety of surface structures in animal pathogens and is implicated as a virulence strategy. This review provides an overview of the many bacterial proteins and structures that are under the control of phase or antigenic variation. The context is mainly within the role of the proteins and variation for pathogenesis, which reflects the main body of literature. The occurrence of phase variation in expression of genes not readily recognizable as virulence factors is highlighted as well, to illustrate that our current knowledge is incomplete. From recent genome sequence analysis, it has become clear that phase variation may be more widespread than is currently recognized, and a brief discussion is included to show how genome sequence analysis can provide novel information, as well as its limitations. The current state of knowledge of the molecular mechanisms leading to phase variation and antigenic variation are reviewed, and the way in which these mechanisms form part of the general regulatory network of the cell is addressed. Arguments both for and against a role of phase and antigenic variation in immune evasion are presented and put into new perspective by distinguishing between a role in bacterial persistence in a host and a role in facilitating evasion of cross-immunity. Finally, examples are presented to illustrate that phase-variable gene expression should be taken into account in the development of diagnostic assays and in the interpretation of experimental results and epidemiological studies.

Amino Acid Sequence↗

Analysis of concerted expression of angiogenic growth factors in acute myeloid leukemia: expression of angiopoietin-2 represents an independent prognostic factor for overall survival.

PURPOSE: Bone marrow neoangiogenesis plays an important pathogenetic and possible prognostic role in acute myeloid leukemia (AML). Members of the vascular endothelial growth factor (VEGF) and angiopoietin family represent the most specific inducers of angiogenesis secreted by AML blasts. We therefore correlated expression of angiogenic factors with clinical variables. PATIENTS AND METHODS: We investigated the expression of VEGF-A, VEGF-C, angiopoietin-1 (Ang1), angiopoietin-2 (Ang2), and the receptor Tie2 by quantitative polymerase chain reaction in a cohort of 90 patients younger than 61 years with de novo AML entered into the German AML Süddeutsche Hämoblastose Gruppe Hannover 95 trial. Uni- and multivariate analyses were performed using clinical and gene expression variables. RESULTS: Univariate analysis of overall survival indicated the following variables as prognostic factors: good response on a day-15 bone marrow examination after initiation of induction chemotherapy, karyotype, and high Ang2 expression. In multivariate analysis, only bad response and log Ang2 expression remained of statistical significance, with a hazard ratio of 3.51 (95% CI, 1.91 to 6.47) and 0.75 (95% CI, 0.61 to 0.91), respectively. Subgroup analysis suggested that the prognostic impact of Ang2 expression was especially evident in cohorts with low VEGF-C and Ang1 mRNA levels. CONCLUSION: These results show that expression of Ang2 represents an independent prognostic factor in AML. Additional research into interactions of angiogenic cytokines in the pathogenesis of bone marrow angiogenesis in AML is warranted.

Acute Disease↗

Gene expression profiling detects gene amplification and differentiates tumor types in breast cancer.

Global gene expression analysis using microarrays has been used to characterize the molecular profile of tumors. Gene expression variability at the mRNA level can be caused by a number of different events, including novel signaling, downstream activation of transcription enhancers or silencers, somatic mutation, and genetic amplification or deletion. Genomic amplifications are commonly observed in cancer and often include known oncogenes. The tyrosine kinase-type cell surface receptor, ERBB2, is an oncogene located on chromosome 17q21.1 that is amplified in 10-40% of breast tumors. We report for the first time that phenylethanolamine N-methyltransferase (PNMT), proteasome subunit, beta type 3 (PSMB3), ribosomal protein L19 (RPL19), and nuclear receptor subfamily 1, group D, member 1 (NR1D1) are coexpressed with ERBB2 in 34 breast cancer biopsies and also mapped within the same chromosomal location as the ERBB2 gene. Consistent with previous reports, we also observed that the steroidogenic acute regulatory protein-related gene, MLN64, and growth factor receptor bound protein 7 were coexpressed with ERBB2. Coexpression and colocalization of PNMT and MLN64 with ERBB2 suggested that the amplification of ERBB2 includes the chromosomal region harboring these genes. This hypothesis was validated in a subset of 12 biopsies. Gene amplification of ERBB2, PNMT, and MLN64 significantly correlated with increased mRNA gene expression (P < 0.05). These results suggest that gene expression profiling of breast biopsies may become a valuable method for adequately characterizing and choosing treatment modality for patients with breast cancer.

Breast Neoplasms↗

Liver regeneration: methods for monitoring and their applications.

Liver regeneration is an essential component of the reparative process following liver injury and surgical resection. It can be assessed by different tissue-based tests such as liver weights, mitotic counts, DNA contents and synthesis rates, immunohistochemical staining of nuclear antigens, gene expressions and certain protein levels or various serum-based tests that largely consist of specific enzyme determinations or documentation of certain proliferation markers. Although the simplest tissue-based test of liver regeneration is measurement of liver weights, these determinations are influenced by the extent of deposition of various materials not directly related to regeneration, such as lipids, glycogen and blood volumes. Because mitosis constitutes a very short segment of the cell cycle, mitotic counts are infrequently observed by light microscopy. Thymidine and BrdU incorporation into DNA are the reference tools for studying DNA synthesis, but their use requires pre-injection with radioactive isotopes or nucleotides which render them impractical for human studies. Flow cytometry is an accurate and objective method of monitoring hepatic regenerative activity but requires sophisticated equipment that is not generally available in many laboratories. Immunohistochemical staining for nuclear antigens (Ki-67, proliferating cell nuclear antigen [PCNA], DNA polymerase alpha and nucleolar organizer region [NOR] proteins) are acceptable and commonly used methods of monitoring regenerative activity but are subject to inter- and intra-observer variability. Gene expression rates such as Histone-3 mRNA abundance are hampered by the relatively low rates of gene transcription and the need for recombinant DNA technology. Protein and enzyme levels in liver tissues, such as putrescine, ornithine decarboxylase and thymidine kinase, are not precise and are confounded by the nutritional status of the host. While PCNA protein levels measured by immunoblot hold promise as a simple, accurate and reproducible marker of liver regeneration, additional studies are required to determine if this is a valid marker of regenerative activity in various models of hepatic injury and in humans. Of the serum-based determinations: thymidine kinase, ornithine decarboxylase, fibronectin, alpha fetoprotein, and early pregnancy factor offer practical and non-invasive tools to monitor liver regeneration, but the sensitivity and specificity of these tests have yet to be determined. In conclusion, many tissue and serum-based methods have been employed in clinical and experimental studies to assess liver regeneration; however, a gold standard has yet to be identified. Because of the disadvantages inherent in each method, and until a new, more accurate marker is identified, clinicians and scientists should incorporate a minimum of two independent markers in studies of liver regeneration.

Animals↗

Autosomal dominant neuromuscular disease with cylindrical spirals.

Cylindrical spirals (CS) have been reported in muscle biopsies from five individual cases, as well as in two belonging to one family where there was another affected member, clinically associated with cramps, pain, stiffness and/or weakness. Here we studied muscle biopsies of a 70-yr-old mother and her 52-yr-old son, the latter with an associated neuropathy, both with late clinical onset in whose family at least 10 other members, spanning five generations, were diversely affected by muscular weakness, gait disorders, motor impairment and/or scoliosis, featuring an autosomal dominant trait with variable expression. CS as the main pathological findings were observed by light microscopy mostly in type 2 fibres, consisting of subsarcolemmal or intermyofibrillar granular and/or rod-like clusters, bluish with haematoxylin, bright red with Gomori's modified trichrome, non- or lightly reactive with PAS, faintly coloured with NADH-TR, non-reactive with SDH or ATPase, strongly stained with non-specific esterase and myoadenylate deaminase. Ultrastructurally, CS appeared as concentrically wrapped lamellae 1-2 microns in diameter. On occasion CS merged into tubular vesicular structures strongly resembling tubular aggregates (TA). Dilation of terminal cisternae (TC) in their proximity supports an origin from the sarcoplasmic reticulum (SR). Variable gene expression possibly explains both the highly diverse clinical compromise and time of onset.

Adult↗

Heparan sulfate (HS)/heparan sulfate proteoglycan (HSPG) and bikunin are up-regulated during calcium oxalate nephrolithiasis in rat kidney.

We reported that expression of both HSPG and of bikunin are increased in calcium oxalate (CaOx) nephrolithic rat kidneys (lida et al., J. Am. Soc. Nephrol. 1999, Urol. Res. 1997). However, these findings were obtained from separate experiments. The present study evaluates whether levels of HSPG and bikunin expression differ in the rat kidney during calcium oxalate nephrolithiasis. Twenty-four male Wistar rats weighing 200-250 g were assigned to one of four groups (n = 6 each group) and administered with 0.5% ethylene glycol daily and 0.5 microgram of 1 alpha-OH-D3 every other day to induce CaOx nephrolithiasis. Animals were sacrificed 1 or 2 weeks later and both kidneys were excised. The cortex was separated from the medulla and papillary tips in the right kidney, then stored in liquid nitrogen for quantitative competitive-reverse transcription-polymerase chain reaction (QC-RT-PCR). The left kidney was fixed in 10% buffered formalin for histochemical studies. We assessed the variable gene expression of both HSPG and bikunin by QC-RT-PCR. Immunohistochemical analyses of left kidney tissue samples determined the localization of HSPG and bikunin. Normal rats serving as controls (n = 6 each) were also sacrificed and processed in the same manner as the experimental groups. QC-RT-PCR confirmed that HSPG and bikunin mRNA expression is significantly increased in nephrolithic kidneys (p < 0.05; Mann-Whitney test), and that medulla and papillary tips tended to express more mRNA of both. Immunohistochemical studies revealed that the production of HS and bikunin was increased in both the distal and proximal tubules of nephrolithic kidneys. These findings suggest that the increased expression of both HSPG and bikunin play an important role during calcium oxalate stone formation. In addition, this phenomenon might be associated with the progression of urothelial damage.

Animals↗

Maintenance of foreign gene expression and independent chromosome fragments in adult transgenic rainbow trout and their offspring.

Transgenic rainbow trout (RT) were generated in earlier experiments by an in vivo modification of the chromosome-mediated gene transfer technique. This involved fertilizing albino RT eggs with gamma-irradiated brook (speckled) trout (ST) sperm and then heat shocking the eggs to induce second polar body retention. Striped pigment patterns were stable in six mosaic individuals between the ages of 7 and 14 months. We estimated the total ST DNA contribution in adult transgenic fish using DNA dot blot analyses. An average of 7% ST DNA was obtained in analyses of 11 transgenic individuals. Nine of 55 transgenic individuals examined expressed a ST-specific isozyme in adulthood; some were mosaic for foreign gene expression. Variable numbers of autonomous chromosome fragments were maintained in 10 adult transgenic individuals examined. Five transgenic RT were backcrossed to albino RT. Chromosome fragments were inherited by 29 of 31 backcross embryos examined. Additional active nucleolar organizer regions (NORs) were present on some fragments and may also have been integrated into some host chromosomes. This method may have numerous applications for basic and applied genetic research in fish.

Animals↗

The Wagner-Stickler syndrome complex.

The Wagner's vitreoretinal degeneration is a condition characterized by myopia, cataract, optically empty vitreous cavity and retinal breaks leading to retinal detachments with poor surgical prognosis. Several extraocular manifestations were reported to be associated with these eye findings and various syndromes were delineated describing sensorineural deafness, orofacial anomalies and skeletal dysplasias. There is enough evidence to suggest that this condition results from a phenotypic variability of genic origin, transmitted as an irregular autosomal dominant trait. In the absence of knowledge about the primary gene defect, the problems in nosology emphasize the difficulty in distinguishing genetic heterogeneity from variable gene expression. In view of the great deal of similarity between all these syndromes with vitreoretinal degeneration it is suggested that all these entities represent the extremes of the same disease spectrum forming parts of a continuum.

Abnormalities, Multiple↗

Pathogenic and non-pathogenic T lymphocytes specific for the encephalitogenic epitope of myelin basic protein: functional characteristics and vaccination properties.

Activated CD4+ T lymphocytes specific for myelin basic protein (MBP) can cause experimental autoimmune encephalomyelitis (EAE) upon their inoculation into syngeneic recipients. In Lewis rats, most of the pathogenic T cell clones that develop following immunization with MBP are reactive against the 72-84 amino acid sequence of MBP, the major encephalitogenic region for Lewis rats. In this study, some MBP-specific T cell clones were found to be non-pathogenic, in spite of their strong reactivity against the encephalitogenic epitope. One of these non-pathogenic clones, designated Znp, and an encephalitogenic clone, Z1a-p, were derived from Z1a encephalitogenic line cells. These subclones were compared for epitope specificity, T cell receptor variable gene expression and for various functional activities, in order to delineate properties crucial for pathogenicity. The Z1a-p and Znp cells expressed comparable levels of the T cell receptor genes and shared strong reactivity against the 72-84 epitope of MBP. The pathogenic Z1a-p cells displayed MBP-specific cytolytic activity in vitro, provided an in-vivo 'help' for elicitation of MBP-specific antibodies, mediated a delayed type hypersensitivity (DTH) response to MBP, caused EAE and vaccinated against the disease, thus demonstrating that a single CD4+ T cell clone is capable of eliciting various functions. The non-pathogenic Znp cells could also carry out most of these various functions, but failed to mediate a DTH response to MBP in normal animals. However, when inoculated into sublethally (650 R) irradiated syngeneic recipients, the Znp cells became highly pathogenic and mediated DTH response to MBP. Local irradiation of the recipient facilitated a DTH response to MBP in the irradiated ear, indicating that Znp cells are equipped with the effector mechanisms required for pathogenicity, and that their failure to cause disease may be accounted for by their inability to migrate into extravascular target tissue. Similar data were obtained with an independently isolated non-pathogenic clone, LB-3, specific for the encephalitogenic epitope of MBP. The ability of these non-pathogenic cells to vaccinate against EAE mediated by pathogenic cells raises the possibility that such non-pathogenic cells may play a role in triggering downregulation of pathogenic T cells.

Animals↗

Deciphering Campylobacter jejuni cell surface interactions from the genome sequence.

The completion of the Campylobacter jejuni genome sequence is a landmark in Campylobacter research. Discoveries directly arising from these data include the identification of a capsular polysaccharide, extensive capacity for phase variable gene expression and lipo-oligosaccharide structural phase variation. The recent identification of a unique system of general protein glycosylation in C. jejuni, a C. jejuni protein that is translocated into eukaryotic cells, and plasmid-encoded components of a putative type IV secretion system are likely to be significant in terms of the host-pathogen interaction.

Antigenic Variation↗