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PubMed2026

Screening Equine Skin and Mucous Membranes for Carriage of Coagulase-Positive Staphylococci.

BACKGROUND: Commensal populations of coagulase-positive Staphylococcus spp. (CoPS) in healthy horses are not well-defined. OBJECTIVE: To determine the point prevalence, anatomical distribution, antimicrobial susceptibility and genomic characteristics of CoPS in healthy horses. ANIMALS: One-hundred and fifty privately owned, systemically healthy horses from seven facilities were enrolled in this study. MATERIALS AND METHODS: Horses were sampled from the nares, buccal mucosa and three skin sites. Isolates were identified using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, and antimicrobial susceptibility testing was performed by gradient diffusion. Whole-genome sequencing with multilocus sequence typing (MLST) characterised Staphylococcus aureus lineages. In silico PCR differentiated Group A and Group B Staphylococcus delphini. Sampling site sensitivity was calculated using a multisite composite reference. Mixed-effects logistic regression evaluated associations between demographic factors and carriage. RESULTS: Carriage of any staphylococcal species occurred in 111 of 150 (74%) horses: S. aureus 28 of 150 horses (18.7%) and S. delphini 23 of 150 horses (15.3%). Increasing age was associated with decreased odds of CoPS isolation (odds ratio 0.92/year; 95% confidence interval 0.86-0.98). The nares were the most sensitive single sampling site, whereas multisite sampling improved detection. Meticillin-resistance was absent in all CoPS isolates, and S. delphini isolates were fully susceptible to all antimicrobials tested. MLST revealed multiple S. aureus sequence types, some of which were shared across multiple horses at some boarding facilities. Both groups of S. delphini lineage were identified, although many isolates were nontypable. CONCLUSIONS AND CLINICAL RELEVANCE: Healthy horses harbour S. aureus and S. delphini, with minimal antimicrobial resistance. Shared S. aureus sequence types within facilities suggest possible lateral transmission.

Animals↗

PubMed2006

Identification of four novel HLA-A alleles from an East African population by high-resolution sequence-based typing.

We report here four novel human leukocyte antigen (HLA)-A alleles identified among an East African population during sequence-based HLA-A typing. The novel alleles were confirmed by sequencing two separate polymerase chain reaction products and by molecular cloning and sequencing multiple clones. The new allele A*9202 is identical to A*0202 at exon 2 and exon 3 except for a single nucleotide difference at codon 43 (CGG-->CAG), resulting in a coding change from Arginine to Glutamine. The second new allele has a synonymous change at codon 139 (GCA-->GCG), that differentiates it from A*680101. The new allele has been named by the World Health Organization nomenclature committee as A*680105. The novel allele A*2630 is identical to A*2603 at exon 2 and exon 3 except for a nonsynonymous change at codon 90 (GAC-->GCC), changed from Aspartic acid to Alanine. The fourth new allele is identical to A*290201 except for a single nucleotide difference at codon 138 (ATG-->GTG), resulting in a coding change from Methionine to Valine. The new allele has been named by the World Health Organization nomenclature committee as A*2915. Identification of these novel HLA-A alleles reflects the genetic diversity of this East African population.

Africa, Eastern↗

PubMed2005

HLA genes in Portugal inferred from sequence-based typing: in the crossroad between Europe and Africa.

The human leukocyte antigen-A (HLA-A), -B and -DRB1 polymorphism was examined in the Portuguese population, discriminating between North, Centre and South inhabitants. All data were obtained at high-resolution level, using sequence-based typing. The most frequent allele at each locus was A* 020101 (26%), B* 440301 and B* 510101 (12% each) and DRB1* 070101 (15%). The predominant three-locus haplotype was A*020101-B*440301-DRB1*070101 (3.1%), highly frequent in North Portugal (5.4%), lower in Centre (2%) and absent in the South. The present study demonstrates that the Portuguese population has been genetically influenced by Europeans and North Africans, via several historic immigrations. North Portugal seems to concentrate, probably due to the pressure of Arab expansion, an ancient genetic pool originated from several North Africans and Europeans, influences throughout millenniums. South Portugal shows a North African genetic influence, probably of recent origin by means of Berbers accompanying Arab expansion. We found that Centre Portugal is the distribution limit of some alleles and haplotypes that characterize the North or the South of the country. Despite North, Centre and South Portugal not being significantly different in allele frequencies, this study shows that HLA allele and haplotype frequencies are not homogeneous in the country. North and South Portugal show more similarity to North Africans in opposition to Centre which appears closer to Europeans.

Africa↗

PubMed2006

[The genetic polymorphism of HLA-DQA1 and HLA-DQB1 genes of Chinese Han population in Jiangsu area is studied by PCR-sequence-based typing].

OBJECTIVE: To investigate the polymorphism of HLA-DQA1 and DQB1 genes of Han population in Jiangsu of China. METHODS: The alleles and haplotypes frequencies of HLA-DQA1 and DQB1 genes in 100 unrelated healthy individuals were analyzed by using polymerase chain reaction-sequence-based typing (PCR-SBT). RESULTS: Among the 7 DQA1 alleles detected, the most common allele was DQA1*0301/02/03 with a frequency of 29.5%, which was followed by DQA1*0501, DQA1*0102 and DQA1*0201 with frequencies of 18.5%, 17.0% and 12.5%, respectively. Of the 13 DQB1 alleles detected, DQB1*0201/02 allele (21.5%) was the most frequent allele, followed by DQB1*0301/09 (14.5%), DQB1*0303 (13.5%) and DQB1*0603 (11.5%). The most common DQA1 vs DQB1 haplotype was DQA1*0301/02/03 vs DQB1*0303 with a frequency of 12.5%, which was followed by the DQA1*0201-DQB1*0201/02 (10.5%),DQA1*0501-DQB1*0201/02 (9.5%) and DQA1*0501-DQB1*0301/09 (7.0%). CONCLUSION: The distribution of HLA-DQ alleles and haplotypes in Jiangsu Han population shares some genetic characteristics with other population in northern of China, but has its own characteristics. The data will provide useful information for anthropology, organ transplantation and disease association studies.

Adult↗

PubMed2026

Mycoplasma and Bartonella in cats from the tropical tourist Gili Islands, Indonesia.

Bartonella spp. and haemotropic Mycoplasma spp. are important vector-borne bacteria of veterinary and zoonotic relevance, yet information on their circulation in Indonesian island ecosystems remains limited. We investigated their occurrence and molecular diversity in 117 domestic and free-roaming cats from the Gili Islands, Indonesia, using full-length 16S rRNA nanopore metagenomics followed by targeted PCR, sequencing, phylogenetic analysis and multilocus sequence typing (MLST). Bartonella DNA was detected in 18/117 (15.4%) cats and haemotropic Mycoplasma DNA in 40/117 (34.2%). Sequence analysis identified Bartonella henselae as the predominant species together with Bartonella clarridgeiae. MLST of B. henselae revealed three sequence types (ST1, ST16 and ST42), with ST1, a lineage reported in both feline and human isolates, predominating. Comparison with the PubMLST database showed significant geographical differences in the distribution of ST1 and ST42, supporting regional variation in the circulation of B. henselae lineages. Haemoplasma characterization identified Candidatus Mycoplasma haemominutum, Mycoplasma haemofelis, Candidatus Mycoplasma turicensis and a Mycoplasma feliminutum-like organism, comprising ten distinct sequence variants. Haemoplasma positivity was significantly associated with age, with adults showing higher positivity than younger animals (P < 0.001), whereas Bartonella infection was not associated with age, sex or island of origin. The detection of zoonotically relevant B. henselae lineages and the genetic diversity of feline haemoplasmas provide evidence of the circulation of vector-borne bacteria among cats in this tropical island ecosystem. These findings provide the first molecular epidemiological baseline for this region and contribute to understanding the circulation and genetic diversity of feline vector-borne pathogens in Southeast Asia.

Animals↗

PubMed2003

Sequence-based typing identifies a novel HLA-DPB1 allele, DPB1*9601.

In this report we describe the identification of a novel HLA-DPB1 allele, DPB1*9601, found in a Caucasian individual sample named ucla#356. The new allele was detected in the DNA of ucla#356 during routine HLA sequence-based typing (SBT) of samples participating in the UCLA International HLA DNA Exchange (number 55) for HLA DNA Proficiency Testing. DPB1*9601 was identical to DPB1*3901 except for a single nucleotide substitution 'G'-->'C' in previously constant position 277 (position 177, respectively, counting only exon 2). This nucleotide change causes an amino acid substitution from aspartic acid in DPB1*3901 to histidine at codon 64 in the novel allele. This new allele has been submitted to the EMBL database and has been assigned the accession number AJ514871. The WHO Nomenclature Committee has officially assigned the name DPB1*9601.

Base Sequence↗

PubMed2006

[Surveillance on pathogens of meningococcal meningitis in Beijing, 2005].

OBJECTIVE: To study the pathogens of meningococcal meningitis (MM) in Beijing, 2005. METHODS: Blood and cerebrospinal fluid specimens from MM patients were detected by polymerase chain reaction. Bacterial strains were analyzed by pulsed-field gel electrophoresis and multilocus sequence typing. RESULTS: 7 of the blood and 5 of cerebrospinal fluid specimens showed positive results. 105 of the Neisseria meningitides strains were isolated from the specimens of patients, close contacts and healthy carriers. Serogroup A and C Neisseria meningitides strains shared the same patterns of pulsed-fieldgel electrophoresis, respectively. The sequence type of serogroup A Neisseria meningitides belonged to ST7 while the sequence type of serogroup C Neisseria meningitides belonged to ST4821. CONCLUSION: Patients suffered from meningococcal meningitis were caused by serogroup A (ST7) and C (ST4821) Neisseria meningitides in Beijing, 2005.

China↗

PubMed2001

Sequencing based typing for HLA-C. Identification of three new alleles: Cw0307, Cw0502 and Cw*0504.

HLA-C has been described as a transplantation locus in the unrelated bone marrow transplantation setting, and noticeably the number of mismatches between HLA-A,-B,-DRB1 compatible pairs is considerably high. Sequencing based typing (SBT) is an accurate and efficient methodology utilised in the HLA class I and II allele level of resolution. SBT for HLA-C locus was applied on a sample of 40 HLA-A,B,DRB1,DRB3/4/5,DQB1-compatible bone marrow recipient-donor pairs, and 3 new HLA-C alleles have been found. Cw*0307, well defined by serology as Cw3, showed two amino acid changes at the NK motif 77-80 regarding all described Cw*03 alleles, N77K80 instead of S77N80. Two new Cw*05 alleles were described, Cw*0502 properly typed by serology, and Cw*0504 that behaves as a short antigen. Cw*0502 differed from Cw*0501 by only one nucleotide at exon 3, that generated an amino acid replacement at codon 177, K to E. Cw*0504 differs from Cw*0501 by two clustered amino acid positions (114 and 116) placed at the peptide binding site. The rate of new HLA-C alleles found in this small series evidences a high grade of hidden HLA-C diversity in the Spanish population, particularly in the well-defined serologic specificities.

Alleles↗

PubMed1984

The wild-type nucleotide sequence of the rpoBC-attenuator region of Escherichia coli DNA and its implications for the nature of the rifd18 mutation.

To investigate the possibility that the unusual dominant rifampicin-resistance characteristic of the rifd18 allele of E. coli rpoB is due to a secondary, regulatory mutation, we have determined the nucleotide sequence of a 1.1 Kbp wild-type DNA fragment, including the transcriptional attenuator and translational start-site of rpoB. We have also re-investigated the previously published sequences of this region in lambda rifd18 and lambda rifd47 DNA. Our results indicate that all three sequences are identical, and reveal some errors in the published data. We discuss the basis of dominance of rifd18.

Alleles↗

PubMed2005

MICA polymorphism in a population from north Morocco, Metalsa Berbers, using sequence-based typing.

The MICA gene encodes a family of nonclassical major histocompatibility complex class I molecules. Data on MICA polymorphism in different populations are still limited. In the present study, MICA allele frequencies (af) were assessed in 82 unrelated healthy individuals from a Moroccan Berber population named Metalsa (ME) by means of sequence-based typing of exons 2, 3, 4, and 5. In consideration of the linkage disequilibrium existing between MICA and human leukocyte antigen (HLA) class I alleles, MICA/HLA-B, MICA/HLA-Cw, and MICA/HLA-A haplotype frequencies (hf) were estimated. A wide allelic distribution including 16 different MICA alleles was found in ME. The most common MICA alleles were MICA*00801 (af = 0.268), *004 (0.232), *00902 (0.140), *00901 (0.085), and *00901 (0.073). The most common MICA/HLA-B haplotypes were MICA*004-B*4403 and MICA*009-B*50 (hf = 0.113 for both these haplotypes). Some known MICA and HLA-B associations were confirmed in this population. Noteworthy was the high frequency of MICA*009 (af = 0.226); the high frequency of B*50 found in ME (af = 0.114) permitted us to evidence the associations of MICA*00902 with B*5001 (hf = 0.068) or *5002 (hf = 0.045), whereas MICA*00901 was mainly associated with B*5101 (hf = 0.038), which corresponds to the previously described association MICA*009/A6-HLA-B*51. This study extends the previous knowledge on MICA polymorphism to a North African white population and may have implications for disease associations and transplantation.

Adolescent↗

PubMed2006

A successful, diverse disease-associated lineage of nontypeable pneumococci that has lost the capsular biosynthesis locus.

Streptococcus pneumoniae strains which fail to produce a polysaccharide capsule are commonly isolated from carriage and disease contexts. Here we use a multilocus approach to distinguish genuine nontypeable pneumococci from closely related nontypeable streptococcal isolates in a data set of 121 untypeable pneumococci from nasopharyngeal swabs and middle ear fluid of Finnish children and demonstrate that 70 of these belong to a pneumococcal lineage which has lost its capsular locus. Strains of this relatively old lineage include sequence types 344, 448, and 449. Comparison with the multilocus sequence typing database shows that strains of this lineage have spread intercontinentally and have been isolated from carriage, mucosal, and invasive disease. Furthermore we note a particular association of this nontypeable lineage with outbreaks of conjunctivitis. The diversification and geographic spread of this lineage suggest that loss of capsule is not inconsistent with long-term persistence and raise questions about the capsule's role in pneumococcal transmission.

Bacterial Typing Techniques↗

PubMed2003

Sequence-based typing of Legionella pneumophila serogroup 1 offers the potential for true portability in legionellosis outbreak investigation.

Seven gene loci of Legionella pneumophila serogroup 1 were analyzed as potential epidemiological typing markers to aid in the investigation of legionella outbreaks. The genes chosen included four likely to be selectively neutral (acn, groES, groEL, and recA) and three likely to be under selective pressure (flaA, mompS, and proA). Oligonucleotide primers were designed to amplify 279- to 763-bp fragments from each gene. Initial sequence analysis of the seven loci from 10 well-characterized isolates of L. pneumophila serogroup 1 gave excellent reproducibility (R) and epidemiological concordance (E) values (R = 1.00; E = 1.00). The three loci showing greatest discrimination and nucleotide variation, flaA, mompS, and proA, were chosen for further study. Indices of discrimination (D) were calculated using a panel of 79 unrelated isolates. Single loci gave D values ranging from 0.767 to 0.857, and a combination of all three loci resulted in a D value of 0.924. When all three loci were combined with monoclonal antibody subgrouping, the D value was 0.971. Sequence-based typing of L. pneumophila serogroup 1 using only three loci is epidemiologically concordant and highly discriminatory and has the potential to become the new "gold standard" for the epidemiological typing of L. pneumophila.

Bacterial Proteins↗

PubMed2004

Separate control of Rep and Cap expression using mutant and wild-type loxP sequences and improved packaging system for adeno-associated virus vector production.

Adeno-associated virus (AAV) vectors are a practical choice for gene transfer, and demand for them is increasing. To cope with the necessity in the near future, we have developed a number of approaches to establish packaging cell lines for the production of AAV vectors. In our previous study, a highly regulated expression of large Rep proteins was obtained by using the Cre-loxP switching system. Therefore, in the present study, to regulate Cap expression as well, we developed an inducible expression system for both Rep and Cap proteins by using an additional set of mutant loxP sequences. The mutants possess two base alterations in the spacer region of loxP and recombine specifically with the same counterpart in the presence of Cre. By using two separate plasmids, one with mutant and the other with wild-type loxP sequences, the expression of two different proteins can be induced simultaneously by Cre recombinase. When the LacZ-encoding plasmid vector was used as a packaging model, a significant packaging titer of 2.1 x 1010 genome copies per 10-cm dish was obtained. These results indicate the importance of controlling Cap expression, in addition to Rep, to achieve an optimum production rate for AAV vectors.

Cell Line↗

PubMed2001

Sequence-based typing of HLA class I alleles in Alaskan Yupik Eskimo.

In comparison to South America, native North Americans tend to be less diverse in their repertoire of HLA class I alleles. Based upon this observation, we hypothesized that the Yupik Eskimo would exhibit a limited number of previously identified class I HLA alleles. To test this hypothesis, sequence-based typing was performed at the HLA-A, -B and -C loci for 99 Central Yupik individuals from southwestern Alaska. Two new class I alleles, A*2423 and Cw*0806, were identified. While A*2423 was observed in only one sample, Cw*0806 was present in 26 of the 99 individuals and all of the Cw*0806 samples contained B*4801. Allele Cw*0806 differs from Cw*0803 by a single nucleotide substitution such that Cw*0803 may be the progenitor of Cw*0806. Allele Cw*0803 was originally characterized as unique to South America, but detection of Cw*0803 in the Yupik indicates that Cw*0803 was a founding allele of the Americas. The presence of new alleles and previously unrecognized founding alleles in the Yupik population show that natives of North America are more diverse than previously envisioned.

Alaska↗

PubMed2005

Plasmodium vivax dihydrofolate reductase point mutations from the Indian subcontinent.

Mutations in Dihydrofolate Reductase (dhfr) gene of Plasmodium vivax are known to be associated with resistance to antifolate drugs. To analyze the extent of these mutations in P. vivax population in India, dhfr gene was isolated and sequenced for 121 P. vivax isolates originating from different geographical regions of Indian subcontinent. These sequences were compared with the gene sequence that represent wild type sequence (accession no. X98123). P. vivax dhfr (Pvdhfr) sequences showed limited polymorphism and about 70% isolates showed wild type dhfr sequence. A total of 36 mutations were found at 11 positions in 121 isolates. A majority of mutant isolates showed double mutations at residues 58 (S-->R) and 117 (S-->N), known to be associated with pyrimethamine resistance, but only 19% showed double mutations at residues 57 (F-->L) and 58 (S-->R). Pvdhfr alleles showing quadruple mutation (F57L, S58R, T61M and S117T) were found in two isolates. Three other mutations reported earlier at residue 13, 33 and 173 were not found in any of the Isolates. Six novel mutations at residues 38 (R-->G), 93 (S-->C), 109 (S-->H), 131 (R-->G), 159 (V-->A) and 188 (I-->V) were observed in seven isolates. Whether these novel mutations are linked to pyrimethamine resistance remains to be established.

Amino Acid Sequence↗

PubMed2002

Two new HLA Cw* alleles, Cw0105 and Cw1405, detected by sequence based typing.

During recent years, the view of the relative importance of the HLA Cw locus has undergone substantial change. From being an HLA locus with both limited polymorphism and biological significance there are now more than a hundred different alleles known and the biological importance of HLA Cw, both as a transplantation antigen and as a receptor for NK cells, is well established. Sequence based typing has been shown to be a powerful tool, especially for HLA Cw typing. Here we describe two new HLA Cw* alleles found during routine typing of potential bone marrow donors and hematological patients. The HLA Cw*0105 differs from Cw*0102 at positions 361 and 368 in exon 3 leading to a Trp to Arg and Cys to Ser substitution, respectively. HLA Cw*1405 differs from Cw*14021 by a single nucleotide substitution at position 368. This mutation results in an amino acid substitution of Phe for Tyr.

Alleles↗

PubMed2001

HLA-DPA1 and DPB1 polymorphism in four Pacific Islands populations determined by sequencing based typing.

Class II HLA-DP antigens are heterodimers comprised of alpha and beta chains coded by HLA-DPA1 and HLA-DPB1 genes. Both genes are polymorphic with substantial variation between different populations world wide. This work describes DPA1 and DPB1 polymorphism in four Pacific Island populations of Cook Islands, Samoa, Tokelau and Tonga, living in New Zealand. Using sequencing based typing four DPA1 alleles and twelve DPB1 alleles were observed in total among the four populations. There are two predominant DPA1 alleles DPA1*01031 and DPA1*02022 and three predominant DPB1 alleles DPB1*02012, DPB1*0401 and DPB1*0501. Fourteen DPA1-DPB1 haplotypes in total are present in these four populations with three predominant haplotypes: DPA1*02022-DPB1*0501, DPA1*01031-DPB1*02012, and DPA1*01031-DPB1*0401. Strong positive and negative disequilibrium was observed for individual DPA1-DPB1 haplotypes. Significant differences in DPA1 and DPB1 allele and haplotype frequencies were observed between Tokelauan and other three populations. Phylogenetic analysis of genetic distances between the four Pacific Island populations and other Asian Oceanian populations have shown that Cook Islanders, Samoans and Tongans are more closely related to Asian populations whereas Tokelauans cluster towards non-Austronesian populations of Papua New Guinea Highlanders and Australian Aborigines.

Algorithms↗

PubMed2002

Sequence-based typing techniques for rhesus macaque MhcMamu-DQB1 allow the identification of more than 35 alleles.

In the recent years, substantial progress has been made in the characterization of the rhesus macaque MHC region, which is more complex than in humans. To cope with the increasing knowledge, improved typing techniques for MHC genes are required. Including the DNA-sequences in this report, 39 rhesus macaque (Mamu)-DQB1 alleles, corresponding to 38 deduced protein sequences, are known. Here, we present a typing technique for Mamu-DQB1 alleles and the DNA-sequences of 9 novel DQB1 alleles. The technique consists of one or two rounds of screening followed by DNA-sequence determination. The first round represents a low-resolution screening sufficiently insensitive to identify novel alleles, which also allows sequencing of both alleles in most heterozygous individuals. The second round consists of a high-resolution screening. This is only necessary for animals in which one PCR-product was generated by the initial screening. The technique was validated by analyzing samples of more than 200 rhesus macaques of different origin, and DNA-sequence determination of more than 230 PCR-products.

Alleles↗