Coinfection with influenza virus and non-typeable Haemophilus influenzae aggregates inflammatory lung injury and alters gut microbiota in COPD mice

Background

Acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is associated with high mortality rates. Viral and bacterial coinfection is the primary cause of AECOPD. How coinfection with these microbes influences host inflammatory response and the gut microbiota composition is not entirely understood.

Methods

We developed a mouse model of AECOPD by cigarette smoke exposure and sequential infection with influenza H1N1 virus and non-typeable Haemophilus influenzae (NTHi). Viral and bacterial titer was determined using MDCK cells and chocolate agar plates, respectively. The levels of cytokines, adhesion molecules, and inflammatory cells in the lungs were measured using Bio-Plex and flow cytometry assays. Gut microbiota was analyzed using 16S rRNA gene sequencing. Correlations between cytokines and gut microbiota were determined using Spearman’s rank correlation coefficient test.

Results

Coinfection with H1N1 and NTHi resulted in more severe lung injury, higher mortality, declined lung function in COPD mice. H1N1 enhanced NTHi growth in the lungs, but NTHi had no effect on H1N1. In addition, coinfection increased the levels of cytokines and adhesion molecules, as well as immune cells including total and M1 macrophages, neutrophils, monocytes, NK cells, and CD4 + T cells. In contrast, alveolar macrophages were depleted. Furthermore, coinfection caused a decline in the diversity of gut bacteria. Muribaculaceae, Lactobacillus, Akkermansia, Lachnospiraceae, and Rikenella were further found to be negatively correlated with cytokine levels, whereas Bacteroides was positively correlated.

Conclusion

Coinfection with H1N1 and NTHi causes a deterioration in COPD mice due to increased lung inflammation, which is correlated with dysbiosis of the gut microbiota.

Identifying and Exploring the Candidate Susceptibility Genes of Cirrhosis Using the Multi-Tissue Transcriptome-Wide Association Study

Objective: We identify and explore the candidate susceptibility genes for cirrhosis and their underlying biological mechanism.

Methods: We downloaded the genome-wide association studies summary data of 901 cirrhosis cases and 451,363 controls and integrated them with reference models of five potential tissues from the Genotype-Tissue Expression (GTEx) Project, including whole blood, liver, pancreas, spleen, and thyroid, to identify genes whose expression is predicted to be associated with cirrhosis. Then, we downloaded gene expression data of individuals with hepatocellular carcinoma from TCGA database to conduct differential expression analysis to validate these identified genes and explored their possible role in driving cirrhosis via functional enrichment and gene set enrichment analysis (GSEA).

Results: We identified 10 significant genes (SKIV2L, JPH4, UQCC2, RP11-91I8.3, MAU2, ERAP1, PUS3, ZNF677, ARHGAP40, and SHANK3) associated with cirrhosis at a Bonferroni-corrected threshold of p < 0.01, among which two (SKIV2L and JPH4) were identified in the liver and five (SKIV2L, JPH4, MAU2, SHANK3, and UQCC2) were validated by differential expression analysis at an FDR-corrected threshold of p < 0.01. The enrichment analysis showed that the degradation process of RNA, which is enriched by 58 genes, is significantly under-enriched in liver cancer tissues (p = 0.0268).

Conclusion: We have identified several candidate genes for cirrhosis in multiple tissues and performed differential genetic analysis using the liver cancer database to verify the significant genes. We found that the genes SKIV2L and JPH4 identified in the liver are of particular concern. Finally, through enrichment analysis, we speculate that the process of mRNA transcription and RNA degradation may play a role in cirrhosis.

Unusual matrine-adenine hybrids isolated from Sophora davidii and their inhibitory effects on human cytomegalovirus

A phytochemical investigation on the flowers of Sophora davidii resulted in the isolation of three unusual matrine-adenine hybrids, sophovicines A-C, together with biogenetically related analogue sophocarpine. Their structures and absolute configurations were determined by NMR analysis, single-crystal X-ray diffraction, and electronic circular dichroism (ECD) data. Since sophovicines represent the first example of matrine-adenine hybrids, a putative biosynthetic pathway toward sophovicines A-C was proposed. In addition, computational molecular modeling suggested that compounds sophovicines B and C may have potent activities against human cytomegalovirus (HCMV). So, the inhibit effects of isolates on HCMV were evaluated. The results show that sophovicines B and C can inhibit HCMV replication effectively with IC₅₀ values of 7.12 and 7.32 μM, respectively.

Rapid and Simultaneous Detection of Five, Viable, Foodborne Pathogenic Bacteria by Photoinduced PMAxx-Coupled Multiplex PCR in Fresh Juice

Escherichia coli, Staphylococcus aureus, Shigella, Pseudomonas aeruginosa, and Klebsiella pneumoniae are common foodborne pathogens. In this study, the light-induced PMAxx-coupled multiplex PCR (PMAxx-mPCR) was established to detect the aforementioned five foodborne pathogens in fresh juice at the same time. Moreover, PMAxx pretreatment could effectively distinguish live bacteria from dead bacteria. The optimized PMAxx pretreatment conditions were incubation with a final concentration of 10 μmol/L PMAxx for 10 min and then photolysis for 8 min. After PMAxx pretreatment, the difference in Ct values with or without PMAxx was determined by quantitative real-time PCR. The results showed a significant difference in Ct value before and after PMAxx treatment. Finally, the bacteria-contaminated fresh juice samples treated with PMAxx dye were detected by mPCR. The detection limit of PMAxx-mPCR was 10² colony-forming units (CFU)/mL for E. coli, Shigella, P. aeruginosa, and K. pneumoniae and 10³ CFU/mL for S. aureus. Compared with mPCR detection of samples without PMAxx treatment, the proposed method solved the false-positive problem due to dead bacteria. Hence, an accurate and efficient method for the simultaneous detection of five types of pathogenic bacteria was established. This method could be applied to analytical procedures for ensuring food safety.

Malaria: elimination tale from Yunnan Province of China and new challenges for reintroduction

Background

Eradication of infectious disease is the sanctified public health and sustainable development goal around the world.

Main body

Three antimalarial barriers were developed to control imported malarial cases, and an effective surveillance strategy known as the “1–3–7 approach” was developed to eliminate malaria from the Chinese population. From 2011 to 2019, 5254 confirmed malaria cases were reported and treated in Yunnan Province, China. Among them, 4566 cases were imported from other countries, and 688 cases were indigenous from 2011 to 2016. Since 2017, no new local malarial case has been reported in China. Thus, malaria has been completely eliminated in Yunnan Province. However, malaria is detected in overseas travellers on a regular basis, such as visitors from neighbouring Myanmar.

Conclusion

Hence, the strategies should be further strengthened to maintain a robust public health infrastructure for disease surveillance and vector control programs in border areas. Such programs should be supported technically and financially by the government to avert the possibility of a malarial resurgence in Yunnan Province.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-021-00866-9.

Polymorphisms rs763110 in FASL is linked to hepatitis C virus infection among high-risk populations

BACKGROUND

The Fas cell surface death receptor (FAS) and Fas ligand (FASL) can participate in the apoptosis of immune cells and target cells infected with a virus through the FAS-FASL signalling pathway. The decoy receptor 3 (DCR3) can competitively inhibit the binding of FAS to FASL. Our aim is to investigate the effect of single nucleotide polymorphisms (SNPs) in FAS, FASL and DCR3 on hepatitis C virus (HCV) infection.

METHODS

Four SNPs (rs763110 in FASL, rs1324551 and rs2234767 in FAS and rs2257440 in DCR3) were genotyped in 1495 controls free of HCV, 522 individuals with spontaneous HCV clearance and 732 patients with hepatitis C virus infection. The RegulomeDB database and RNAfold web servers were used to explore potential biological functions of SNPs.

RESULTS

FASL rs763110 was associated with susceptibility to HCV infection, and not to CHC. The odds ratio (95% confidence interval) of HCV infection in high-risk populations carrying FASL rs763110-TT was 1.82 (1.36-2.51, P < 0.001) compared to that of CC genotypes and 1.93 (1.43-2.60, P < 0.001) higher than that of CC + CT genotypes. Based on computer simulation, FASL rs763110-T may affect the transcription of mRNA by affecting the binding of a transcription factor, leading to structural changes in mRNA.

CONCLUSION

The genetic variant in FASL is linked with HCV infection, but not to spontaneous HCV clearance.

Loop-Mediated Isothermal Amplification Assay for Rapid Detection of Hypothetical Protein Gene in Escherichia Coli Clinical Isolates

BACKGROUND

Escherichia coli is the most common pathogenic bacteria that frequently causes life-threatening opportunistic human infections, diarrhea, and septicemia in immunocompromised hosts.

METHODS

This study aimed to establish a loop-mediated isothermal amplification (LAMP) method for the rapid and sensitive detection of a hypothetical protein from an E. coli-specific gene (GenBank ID: 13702648). The gene was obtained through local and online BLAST, and specific primers were designed for this gene. Reaction conditions were optimized at 65ºC for 30 minutes and 80ºC for 2 minutes, whereas the reaction system contained 5.2 mM Mg2+, 8 U of Bst 2.0 DNA polymerase, 1.4 mM deoxyribonucleotide, and 0.2 and 1.6 µM of the outer and inner primers, respectively. The LAMP method was evaluated using 240 strains of E. coli and 150 strains of non-E. coli.

RESULTS

Positive reactions were observed on all 240 strains of E. coli while all non-E. coli strains were negative. Plasmids with the specific gene and mice blood with E. coli were used for sensitivity analysis. The detection limit of LAMP was 100 bacterium/reaction.

CONCLUSIONS

Results showed that the LAMP targeted to the hypothetical protein (GenBank ID: 13702648) is a fast, specific, sensitive, inexpensive, and suitable method for the detection of E. coli.

Infectivity of Zika virus on primary cells support tree shrew as animal model

Zika virus (ZIKV) is a mosquito-borne flavivirus that caused the public health emergency. Recently, we have proved a novel small animal tree shrew was susceptive to ZIKV infection and presented the most common rash symptoms as ZIKV patients. Here we further cultured the primary cells from different tissues of this animal to determine the tissue tropism of ZIKV infection in vitro. The results showed that the primary cells from tree shrew kidney, lung, liver, skin and aorta were permissive to ZIKV infection and could support viral replication by the detection of viral specific RNA intra- and extra-cells. In comparing, the skin fibroblast and vascular endothelial cells were highly permissive to ZIKV infection with high releasing of active virus particles in supernatants proved by its infectivity in established neonatal mouse model. The expressions of ZIKV envelop and nonstructural protein-1, and the effects and strong immune response of primary tree shrew cells were also detected followed by ZIKV infection. These findings provide powerful in vitro cell-level evidence to support tree shrew as animal model of ZIKV infection and may help to explain the rash manifestations in vivo.

Genetic variants in IFIH1 and DDX58 influence hepatitis C virus clearance in Chinese Han population

AIMS

To investigate the association between two RIG-I-like receptor gene polymorphisms and hepatitis C virus (HCV) infection in Chinese Han population.

METHODS

The current study genotyped two selected SNPs (IFIH1 rs3747517 and DDX58 rs9695310) using TaqMan allelic discrimination assay to assess their association with the susceptibility and clinical outcome of HCV infection among 3065 participants (1545 non-HCV infection individuals, 568 spontaneous HCV clearance cases, and 952 persistent infection patients).

RESULTS

IFIH1 rs3747517 (dominant model: Adjusted odds ratio [OR] = 1.34, 95% confidence interval [CI] = 1.07-1.68; P = 0.009) and DDX58 rs9695310 (dominant model: Adjusted OR = 1.43, 95% CI = 1.15-1.78; P = 0.001) were associated with chronic hepatitis C (CHC). And the risk of CHC increased when people were carrying more unfavorable rs3747517-GA/AA and rs9695310-GC/CC genotypes from zero to two with the chronic rates of 56.72%, 59.38%, and 69.01%, respectively (Ptrend  < 0.001).

CONCLUSION

Genetic variations at IFIH1 rs3747517 and DDX58 rs9695310 were independent predictors of chronic hepatitis C in Chinese Han population.

Establishment of loop-mediated isothermal amplification for rapid detection of Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of the three most pathogenic bacteria that frequently cause life-threatening opportunistic human infections, pneumonia, and lower respiratory tract infections in immunocompromised hosts, particularly in the burns ward. The present study aimed to establish a loop-mediated isothermal amplification (LAMP) method for the rapid and sensitive detection of P. aeruginosa-specific gene hypothetical protein (GenBank ID: 882161). The gene was obtained through local and online BLAST, and specific primers were designed for this gene. Reaction conditions were optimized at 65°C for 30 min and 80°C for 2 min, whereas the reaction system contained 5.2 mM Mg²⁺, 8 U Bst 2.0 DNA polymerase, 1.4 mM deoxyribonucleotide and 0.2 and 1.6 µM of the outer and inner primers, respectively. The LAMP method was evaluated using 150 P. aeruginosa and 170 non-P. aeruginosa strains. Positive reactions were observed on 150 P. aeruginosa strains, whereas all non-P. aeruginosa strains exhibited negative results. Plasmids with the specific gene and mouse blood with P. aeruginosa were used for sensitivity assay. The detection limit of LAMP was 1 bacterium/reaction. Results indicated that the LAMP method targeted to hypothetical protein is a fast, specific, sensitive, inexpensive and suitable method for detection of P. aeruginosa.

Vitamin D binding protein polymorphisms influence susceptibility to hepatitis C virus infection in a high-risk Chinese population

Vitamin D binding protein (VDBP) plays an important role in the immune modulation and pathogenesis of hepatitis C viral (HCV) infection by influencing serum vitamin D levels. The present study aims to evaluate the association of VDBP genetic polymorphisms with susceptibility to and chronicity of HCV infection in a high-risk Chinese population. Seven genetic variants in the VDBP gene were genotyped in a case-control study of 886 patients with HCV persistent infection, 539 subjects with spontaneous clearance, and 1081 uninfected controls. Logistic regression analysis was used to assess the effects of these variants on HCV infection outcomes. The results showed that two variants rs7041-G and rs3733359-T alleles were significantly associated with increased susceptibility of HCV infection, and the combined effect of the two unfavorable alleles was related to an elevated risk of HCV infection in a locus-dosage manner (P_trend = 8.16 × 10^-4). Interaction analysis manifested that rs7041-GT/GG and rs3733359-CT/TT jointly increased risk of HCV infection. Moreover, haplotype analysis suggested that compared with the most frequent TC haplotype, the haplotype carrying GT indicated a risk effect of HCV infection [odds ratio (OR) = 1.464]. However, no significant associations were observed for the other five variants. These findings implied that VDBP rs7041-G and rs3733359-T variants may contribute to increased susceptibility to HCV infection in a high-risk Chinese population.

Anterograde monosynaptic transneuronal tracers derived from herpes simplex virus 1 strain H129

Background

Herpes simplex virus type 1 strain 129 (H129) has represented a promising anterograde neuronal circuit tracing tool, which complements the existing retrograde tracers. However, the current H129 derived tracers are multisynaptic, neither bright enough to label the details of neurons nor capable of determining direct projection targets as monosynaptic tracer.

Methods

Based on the bacterial artificial chromosome of H129, we have generated a serial of recombinant viruses for neuronal circuit tracing. Among them, H129-G4 was obtained by inserting binary tandemly connected GFP cassettes into the H129 genome, and H129-ΔTK-tdT was obtained by deleting the thymidine kinase (TK) gene and adding tdTomato coding gene to the H129 genome. Then the obtained viral tracers were tested in vitro and in vivo for the tracing capacity.

Results

H129-G4 is capable of transmitting through multiple synapses, labeling the neurons by green florescent protein, and visualizing the morphological details of the labeled neurons. H129-ΔTK-tdT neither replicates nor spreads in neurons alone, but transmits to and labels the postsynaptic neurons with tdTomato in the presence of complementary expressed TK from a helper virus. H129-ΔTK-tdT is also capable to map the direct projectome of the specific neuron type in the given brain regions in Cre transgenic mice. In the tested brain regions where circuits are well known, the H129-ΔTK-tdT tracing patterns are consistent with the previous results.

Conclusions

With the assistance of the helper virus complimentarily expressing TK, H129-ΔTK-tdT replicates in the initially infected neuron, transmits anterogradely through one synapse, and labeled the postsynaptic neurons with tdTomato. The H129-ΔTK-tdT anterograde monosynaptic tracing system offers a useful tool for mapping the direct output in neuronal circuitry. H129-G4 is an anterograde multisynaptic tracer with a labeling signal strong enough to display the details of neuron morphology.

Electronic supplementary material

The online version of this article (doi:10.1186/s13024-017-0179-7) contains supplementary material, which is available to authorized users.

Translocation of microbes and changes of immunocytes in the gut of rapid- and slow-progressor Chinese rhesus macaques infected with SIVmac239

Human/simian immunodeficiency virus (HIV/SIV) infection can cause severe depletion of CD4(+) T cells in both plasma and mucosa; it also results in damage to the gut mucosa barrier, which makes the condition more conducive to microbial translocation. In this study, we used SIV-infected Chinese rhesus macaques to quantify the extent of microbial translocation and the function of immune cells in the entire gastrointestinal tract and to compare their differences between rapid and slow progressors. The results showed that in the slow progressors, microbial products translocated considerably and deeply into the lamina propria of the gut; the tissue macrophages had no significant differences compared with the rapid progressors, but there was a slightly higher percentage of mucosal CD8(+) T cells and a large amount of extracellular microbial products in the lamina propria of the intestinal mucosa of the slow progressors. The data suggested that although microbial translocation increased markedly, the mucosal macrophages and CD8(+) T cells were insufficient to clear the infiltrated microbes in the slow progressors. Also, therapies aimed at suppressing the translocation of microbial products in the mucosa could help to delay the progression of SIV disease.

Targeted next-generation sequencing of candidate genes reveals novel mutations in patients with dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a major cause of sudden cardiac death and heart failure, and it is characterized by genetic and clinical heterogeneity, even for some patients with a very poor clinical prognosis; in the majority of cases, DCM necessitates a heart transplant. Genetic mutations have long been considered to be associated with this disease. At present, mutations in over 50 genes related to DCM have been documented. This study was carried out to elucidate the characteristics of gene mutations in patients with DCM. The candidate genes that may cause DCM include MYBPC3, MYH6, MYH7, LMNA, TNNT2, TNNI3, MYPN, MYL3, TPM1, SCN5A, DES, ACTC1 and RBM20. Using next-generation sequencing (NGS) and subsequent mutation confirmation with traditional capillary Sanger sequencing analysis, possible causative non-synonymous mutations were identified in ~57% (12/21) of patients with DCM. As a result, 7 novel mutations (MYPN, p.E630K; TNNT2, p.G180A; MYH6, p.R1047C; TNNC1, p.D3V; DES, p.R386H; MYBPC3, p.C1124F; and MYL3, p.D126G), 3 variants of uncertain significance (RBM20, p.R1182H; MYH6, p.T1253M; and VCL, p.M209L), and 2 known mutations (MYH7, p.A26V and MYBPC3, p.R160W) were revealed to be associated with DCM. The mutations were most frequently found in the sarcomere (MYH6, MYBPC3, MYH7, TNNC1, TNNT2 and MYL3) and cytoskeletal (MYPN, DES and VCL) genes. As genetic testing is a useful tool in the clinical management of disease, testing for pathogenic mutations is beneficial to the treatment of patients with DCM and may assist in predicting disease risk for their family members before the onset of symptoms.

[The function and application of the IL28B gene in HCV infection and treatment]

Hepatitis C virus (HCV) is the etiological factor for Hepatitis C, which is one of the most important pathogenic factors of chronic liver diseases, cirrhosis and even hepatocellular carcinoma. HCV infection brings great threat to human health. Host genetic background could impact HCV infection, viral clearance, and treatment. Recently, some genome-wide association studies (GWAS) of HCV patients were performed. The results showed that single nucleotide polymorphisms (SNPs) of the IL28B gene, which encodes protein IFN-lambda3, are associated with viral clearance and treatment effectiveness of HCV patients who were cured by PEG-IFNalpha combined with ribavirin (RBV). IFN-lambda3 interacts with its acceptor, a heterodimer (IFN-lambdaR1 x IL-10R2), and upregulates the IFN-stimulated gene factors (ISGF). IFN-lambda3 plays roles in antiviral, antitumor, and immunoloregulation, and thus it might become a potential drug for Hepatitis C treatment. However, the mechanism of the IL28B gene in HCV infection and treatment is unclear, and further studies are needed to reveal the veils and provide theoretical basis for developing a new antiviral drug in clinic.

[Isolation and identification of Tupaia orthoreovirus]

Pathogenic viruses can harm acutely the life and health of laboratory tree shrews acutely; however, few papers exist regarding natural pathogenic virus infection in this species. Six fecal samples obtained from dead tree shrews were collected. The fecal supernatant infected Vero cell line resulted in cytopathic effects (CPE) after 72 h. The CPE included granulating, shrinking, rounding, seining and falling off. Electron microscopy showed the isolation was spherical, double-layered capsid, and about 75 nm in diameter. The purified isolation genome was 10 segments in a typical 3:3:4 arrangements, as shown by polyacrylamide gel electrophoresis (PAGE). The isolation was confirmed by RT-PCR assays targeting the conserved region of the L1 gene, sequence analysis and reconstruction of a phylogenetic tree. The isolation was a Tupaia Orthoreovirus (TRV), belonging to Mammalian Orthoreovirus (MRV). The obtained strain had the closest phylogenetic relationship to the MRV strain T3/Bat/Germany/342/08. As a zoonotic virus, the novel TRV strain was first isolated from wild tree shrews, which is significant for promoting tree shrew standardization and providing scientific data for preventing zoonotic tree shrew-to-human transmission.

Compounds from Arnebia euchroma and their related anti-HCV and antibacterial activities

Three new hydroquinone terpenoids with benzogeijerene skeletons, euchroquinols A-C (1- 3), and a new monoterpenylbenzenoid, 9,17-epoxyarnebinol (4), along with five known compounds were isolated from the stem bark of ARNEBIA EUCHROMA. Shikonin (6) exhibited potent anti-HCV activity with a selective index of 43.56, and compounds 1, 6, and des-O-methyllasiodiplodin (7) showed anti-Staphylococcus aureus activity with MICs of 0.5, 0.125, and 0.125 mg/mL, respectively.

[Cloning of full-length coding sequence of tree shrew CD3E and prediction of its molecular characteristics]

The use of tree shrews (Tupaia belangeri) in human disease studies demands essential research tools, in particular cellular markers and their monoclonal antibodies for immunological studies. Here we cloned the full-length cDNAs encoding CD3E from total RNA of the spleen, liver and peripheral blood of tree shrews and analyzed their structural characteristics in comparison with other mammals by Discovery Studio software. The results showed that the open reading frame sequence of tree shrew CD3E was 582 bp, encoding 194 amino acids. The overall structure of tree shrew CD3E protein was similar to its counterparts of other mammals, intracellular and transmembrane domain highly conserved. However, detailed analysis revealed two potential glycosylation sites and different surface charges in the extracellular domain. Availability of the entire open-reading-frame and related sequence information would therefore facilitate the preparation of monoclonal antibodies against tree shrew CD3 and further studies for its function.

A novel plasmid pIJB1 possessing a putative 2,4-dichlorophenoxyacetate degradative transposon Tn5530 in Burkholderia cepacia strain 2a

A 102-kb plasmid, pIJB1, was isolated from Burkholderia cepacia strain 2a, which is able to use 2,4-dichlorophenoxyacetate (2,4-D) as a sole carbon source, and a physical map of the plasmid has been established. It was observed that spontaneous loss of a 37-kb fragment of the plasmid after growth in nonselective medium occurred, generating a plasmid of diminished size, pIJB2. The deletion event is concomitant with the loss of the 2,4-D dissimilatory phenotype, indicating that at least some of the 2,4-D degradative genes are on the missing fragment. The missing fragment is flanked by two identical 4.3-kb insertion sequences (IS) and shows a typical composite transposon structure of 41-kb in size, designated Tn5530. The mutant plasmid pIJB2 possesses a single copy of the IS element.

Identification and sequencing of a novel insertion sequence, IS1471, in Burkholderia cepacia strain 2a

A novel insertion sequence (IS), IS1471, has been identified which is inserted into IS element IS1071 possessed by plasmid pIJB1 in Burkholderia cepacia strain 2a. Nucleotide sequencing has revealed that IS1471 is 1112 bp in length and is flanked by 22/21-bp imperfect inverted repeats with a 3-bp duplication of the target sequence IS1471 contains a single open reading frame encoding a putative polypeptide of 345 amino acids with molecular mass of 39406 Da. Searches of DNA and protein sequence databases did not result in the detection of any homologous IS elements, suggesting that IS1471 is novel and may not belong to any known IS groups.