Abstract: Dengue virus (DENV) is the causative agent of Dengue Hemorrhagic Fever and Dengue Shock... more Abstract: Dengue virus (DENV) is the causative agent of Dengue Hemorrhagic Fever and Dengue Shock Syndrome, and continues to represent a major public health hazard. DENVs are antigenically classified in four serotypes and each serotype is further divided into respective genotypes. The association between DENV subtypes and the kind & severity of disease caused by them is known.
The data deluge in post-genomic era demands development of novel data mining tools. Existing mole... more The data deluge in post-genomic era demands development of novel data mining tools. Existing molecular phylogeny analyses (MPAs) developed for individual gene/protein sequences are alignment-based. However, the size of genomic data and uncertainties associated with alignments, necessitate development of alignment-free methods for MPA. Derivation of distances between sequences is an important step in both, alignment-dependant and alignment-free methods. Various alignment-free distance measures based on oligo-nucleotide frequencies, information content, compression techniques, etc. have been proposed. However, these distance measures do not account for relative order of components viz. nucleotides or amino acids. A new distance measure, based on the concept of 'return time distribution' (RTD) of k-mers is proposed, which accounts for the sequence composition and their relative orders. Statistical parameters of RTDs are used to derive a distance function. The resultant distance matrix is used for clustering and phylogeny using Neighbor-joining. Its performance for MPA and subtyping was evaluated using simulated data generated by block-bootstrap, receiver operating characteristics and leave-one-out cross validation methods. The proposed method was successfully applied for MPA of family Flaviviridae and subtyping of Dengue viruses. It is observed that method retains resolution for classification and subtyping of viruses at varying levels of sequence similarity and taxonomic hierarchy.
Bioinformatics, being multidisciplinary field, involves applications of various methods from alli... more Bioinformatics, being multidisciplinary field, involves applications of various methods from allied areas of Science for data mining using computational approaches. Clustering and molecular phylogeny is one of the key areas in Bioinformatics, which help in study of classification and evolution of organisms. Molecular phylogeny algorithms can be divided into distance based and character based methods. But most of these methods are dependent on pre-alignment of sequences and become computationally intensive with increase in size of data and hence demand alternative efficient approaches. `Inter arrival time distribution' (IATD) is a popular concept in the theory of stochastic system modeling but its potential in molecular data analysis has not been fully explored. The present study reports application of IATD in Bioinformatics for clustering and molecular phylogeny. The proposed method provides IATDs of nucleotides in genomic sequences. The distance function based on statistical parameters of IATDs is proposed and distance matrix thus obtained is used for the purpose of clustering and molecular phylogeny. The method is applied on a dataset of 3' non-coding region sequences (NCR) of Dengue virus type 3 (DENV-3), subtype III, reported in 2008. The phylogram thus obtained revealed the geographical distribution of DENV-3 isolates. Sri Lankan DENV-3 isolates were further observed to be clustered in two sub-clades corresponding to pre and post Dengue hemorrhagic fever emergence groups. These results are consistent with those reported earlier, which are obtained using pre-aligned sequence data as an input. These findings encourage applications of the IATD based method in molecular phylogenetic analysis in particular and data mining in general.
An account of bioinformatics education in India is presented along with future prospects. Establi... more An account of bioinformatics education in India is presented along with future prospects. Establishment of BTIS network by Department of Biotechnology (DBT), Government of India in the 1980s had been a systematic effort in the development of bioinformatics infrastructure in India to provide services to scientific community. Advances in the field of bioinformatics underpinned the need for well-trained professionals with skills in information technology and biotechnology. As a result, programmes for capacity building in terms of human resource development were initiated. Educational programmes gradually evolved from the organisation of short-term workshops to the institution of formal diploma/degree programmes. A case study of the Master's degree course offered at the Bioinformatics Centre, University of Pune is discussed. Currently, many universities and institutes are offering bioinformatics courses at different levels with variations in the course contents and degree of detailing. BioInformatics National Certification (BINC) examination initiated in 2005 by DBT provides a common yardstick to assess the knowledge and skill sets of students passing out of various institutions. The potential for broadening the scope of bioinformatics to transform it into a data intensive discovery discipline is discussed. This necessitates introduction of amendments in the existing curricula to accommodate the upcoming developments.
Mumps is an acute infectious disease caused by mumps virus, a member of the family Paramyxovirida... more Mumps is an acute infectious disease caused by mumps virus, a member of the family Paramyxoviridae. With the implementation of vaccination programs, mumps infection is under control. However, due to resurgence of mumps epidemics, there is a renewed interest in understanding the antigenic diversity of mumps virus. Hemagglutinin–neuraminidase (HN) is the major surface antigen and is known to elicit neutralizing antibodies. Mutational analysis of HN of wild-type and vaccine strains revealed that the hypervariable positions are distributed over the entire length with no detectable pattern. In the absence of experimentally derived 3D structure data, the structure of HN protein of mumps virus was predicted using homology modeling. Mutations mapped on the predicted structures were found to cluster on one of the surfaces. A predicted conformational epitope encompasses experimentally characterized epitopes suggesting that it is a major site for neutralization. These analyses provide rationale for strain specificity, antigenic diversity and varying efficacy of mumps vaccines.
Immunoinformatics provides tools for reverse vaccinology and encompasses development of knowledge... more Immunoinformatics provides tools for reverse vaccinology and encompasses development of knowledge bases and algorithms for prediction of epitopes. AgAbDb, a database archiving molecular interactions of antigen-antibody co-crystal structures, has been developed (http://202.41.70.51:8080/agabdb2/). Analyses of antibody-binding sites on proteins helped to fine-tune the parameters for prediction of sequential and conformational B-cell epitopes.
Abstract VirGen is a comprehensive viral genome resource that organizes the &... more Abstract VirGen is a comprehensive viral genome resource that organizes the 'sequence space'of viral genomes in a structured fashion. It has been developed with the objective of serving as an annotated and curated database comprising complete genome sequences of viruses, value‐added derived data and data mining tools. The current release (v1. 1) contains 559 complete genomes in addition to 287 putative genomes of viruses belonging to eight viral families for which the host range includes animals and plants. Viral genomes in ...
Polyclonal or monoclonal human IgM rheumatoid factors (RF) react with eight antigenic sites on th... more Polyclonal or monoclonal human IgM rheumatoid factors (RF) react with eight antigenic sites on the CH3 IgG domain, four sites on CH2 and two on human β2-microglobulin. All 14 of these RF-reactive epitopes are linear 7–11 amino acid peptides with different primary sequence. We questioned whether RF reactivity with such a variety of epitopes showing no obvious sequence homology might result from conformational similarities shared by various RF-reactive regions. Strong support for this concept was obtained using rabbit antisera as well as mouse mAbs to individual CH3, CH2 or β2m RF-reactive peptides. Major cross-reactivity was demonstrated between most of the 14 different CH3, CH2, or β2m RF-reactive peptides using individual anti-epitope antibodies. Molecular modelling studies of these peptides showed striking similarities in three-dimensional shape among many RF-reactive peptides. Main-chain atoms rather than side chains seemed to contribute most directly to conformational similarity. Molecular simulation studies on control peptides showed no conformational similarities with RF-reactive peptides. Our studies indicate that autoantibodies such as RF recognize main-chain conformations of reactive epitopes and react with a number of antigenic determinants of quite different primary sequence but similar main chain conformations.
Transformed B cells making monoclonal IgM-λ anti-PR3 antibody WGH1 from a patient with Wegener's ... more Transformed B cells making monoclonal IgM-λ anti-PR3 antibody WGH1 from a patient with Wegener's granulomatosis were used to prepare mRNA and synthesize cDNA. PCR primers for human μ and λ chains were then employed to amplify heavy- and light-chain V-regions followed by cloning into pCR2-1 vector and sequencing. Molecular modeling of VH regions employed knowledge-based homology modeling to obtain minimum energy conformation. The VH sequence was subgroup III with marked overall homology to VH1.9III. The VHCDR3 region of WGH1 was unique, consisting of 21 amino acid residues which included seven tyrosines as well as three negatively charged aspartic acid residues. The VL region was subgroup II with a negatively charged glutamic acid at position 100 in CDR3. Molecular modeling of VH revealed a major conformational difference in the shape of CDR3 compared with other antibodies for which three-dimensional structures have been determined. Monoclonal antibody WGH1 reacting with PR3 (a highly positively charged molecule) shows a unique reactive cassette within VHCDR3 with a number of negatively charged aspartic acid residues. WGH1 VHCDR3 contains a loop which shows a major projection not usually recorded in other previously studied antibody molecules.
ABSTRACT This paper presents an algorithm for multiple alignment of sequences of proteins and nuc... more ABSTRACT This paper presents an algorithm for multiple alignment of sequences of proteins and nucleic acids on loosely-coupled MIMD machines. An inherently parallel algorithm is devised and implemented on a transputer-based multiprocessor platform. The ...
Abstract: Dengue virus (DENV) is the causative agent of Dengue Hemorrhagic Fever and Dengue Shock... more Abstract: Dengue virus (DENV) is the causative agent of Dengue Hemorrhagic Fever and Dengue Shock Syndrome, and continues to represent a major public health hazard. DENVs are antigenically classified in four serotypes and each serotype is further divided into respective genotypes. The association between DENV subtypes and the kind & severity of disease caused by them is known.
The data deluge in post-genomic era demands development of novel data mining tools. Existing mole... more The data deluge in post-genomic era demands development of novel data mining tools. Existing molecular phylogeny analyses (MPAs) developed for individual gene/protein sequences are alignment-based. However, the size of genomic data and uncertainties associated with alignments, necessitate development of alignment-free methods for MPA. Derivation of distances between sequences is an important step in both, alignment-dependant and alignment-free methods. Various alignment-free distance measures based on oligo-nucleotide frequencies, information content, compression techniques, etc. have been proposed. However, these distance measures do not account for relative order of components viz. nucleotides or amino acids. A new distance measure, based on the concept of 'return time distribution' (RTD) of k-mers is proposed, which accounts for the sequence composition and their relative orders. Statistical parameters of RTDs are used to derive a distance function. The resultant distance matrix is used for clustering and phylogeny using Neighbor-joining. Its performance for MPA and subtyping was evaluated using simulated data generated by block-bootstrap, receiver operating characteristics and leave-one-out cross validation methods. The proposed method was successfully applied for MPA of family Flaviviridae and subtyping of Dengue viruses. It is observed that method retains resolution for classification and subtyping of viruses at varying levels of sequence similarity and taxonomic hierarchy.
Bioinformatics, being multidisciplinary field, involves applications of various methods from alli... more Bioinformatics, being multidisciplinary field, involves applications of various methods from allied areas of Science for data mining using computational approaches. Clustering and molecular phylogeny is one of the key areas in Bioinformatics, which help in study of classification and evolution of organisms. Molecular phylogeny algorithms can be divided into distance based and character based methods. But most of these methods are dependent on pre-alignment of sequences and become computationally intensive with increase in size of data and hence demand alternative efficient approaches. `Inter arrival time distribution' (IATD) is a popular concept in the theory of stochastic system modeling but its potential in molecular data analysis has not been fully explored. The present study reports application of IATD in Bioinformatics for clustering and molecular phylogeny. The proposed method provides IATDs of nucleotides in genomic sequences. The distance function based on statistical parameters of IATDs is proposed and distance matrix thus obtained is used for the purpose of clustering and molecular phylogeny. The method is applied on a dataset of 3' non-coding region sequences (NCR) of Dengue virus type 3 (DENV-3), subtype III, reported in 2008. The phylogram thus obtained revealed the geographical distribution of DENV-3 isolates. Sri Lankan DENV-3 isolates were further observed to be clustered in two sub-clades corresponding to pre and post Dengue hemorrhagic fever emergence groups. These results are consistent with those reported earlier, which are obtained using pre-aligned sequence data as an input. These findings encourage applications of the IATD based method in molecular phylogenetic analysis in particular and data mining in general.
An account of bioinformatics education in India is presented along with future prospects. Establi... more An account of bioinformatics education in India is presented along with future prospects. Establishment of BTIS network by Department of Biotechnology (DBT), Government of India in the 1980s had been a systematic effort in the development of bioinformatics infrastructure in India to provide services to scientific community. Advances in the field of bioinformatics underpinned the need for well-trained professionals with skills in information technology and biotechnology. As a result, programmes for capacity building in terms of human resource development were initiated. Educational programmes gradually evolved from the organisation of short-term workshops to the institution of formal diploma/degree programmes. A case study of the Master's degree course offered at the Bioinformatics Centre, University of Pune is discussed. Currently, many universities and institutes are offering bioinformatics courses at different levels with variations in the course contents and degree of detailing. BioInformatics National Certification (BINC) examination initiated in 2005 by DBT provides a common yardstick to assess the knowledge and skill sets of students passing out of various institutions. The potential for broadening the scope of bioinformatics to transform it into a data intensive discovery discipline is discussed. This necessitates introduction of amendments in the existing curricula to accommodate the upcoming developments.
Mumps is an acute infectious disease caused by mumps virus, a member of the family Paramyxovirida... more Mumps is an acute infectious disease caused by mumps virus, a member of the family Paramyxoviridae. With the implementation of vaccination programs, mumps infection is under control. However, due to resurgence of mumps epidemics, there is a renewed interest in understanding the antigenic diversity of mumps virus. Hemagglutinin–neuraminidase (HN) is the major surface antigen and is known to elicit neutralizing antibodies. Mutational analysis of HN of wild-type and vaccine strains revealed that the hypervariable positions are distributed over the entire length with no detectable pattern. In the absence of experimentally derived 3D structure data, the structure of HN protein of mumps virus was predicted using homology modeling. Mutations mapped on the predicted structures were found to cluster on one of the surfaces. A predicted conformational epitope encompasses experimentally characterized epitopes suggesting that it is a major site for neutralization. These analyses provide rationale for strain specificity, antigenic diversity and varying efficacy of mumps vaccines.
Immunoinformatics provides tools for reverse vaccinology and encompasses development of knowledge... more Immunoinformatics provides tools for reverse vaccinology and encompasses development of knowledge bases and algorithms for prediction of epitopes. AgAbDb, a database archiving molecular interactions of antigen-antibody co-crystal structures, has been developed (http://202.41.70.51:8080/agabdb2/). Analyses of antibody-binding sites on proteins helped to fine-tune the parameters for prediction of sequential and conformational B-cell epitopes.
Abstract VirGen is a comprehensive viral genome resource that organizes the &... more Abstract VirGen is a comprehensive viral genome resource that organizes the 'sequence space'of viral genomes in a structured fashion. It has been developed with the objective of serving as an annotated and curated database comprising complete genome sequences of viruses, value‐added derived data and data mining tools. The current release (v1. 1) contains 559 complete genomes in addition to 287 putative genomes of viruses belonging to eight viral families for which the host range includes animals and plants. Viral genomes in ...
Polyclonal or monoclonal human IgM rheumatoid factors (RF) react with eight antigenic sites on th... more Polyclonal or monoclonal human IgM rheumatoid factors (RF) react with eight antigenic sites on the CH3 IgG domain, four sites on CH2 and two on human β2-microglobulin. All 14 of these RF-reactive epitopes are linear 7–11 amino acid peptides with different primary sequence. We questioned whether RF reactivity with such a variety of epitopes showing no obvious sequence homology might result from conformational similarities shared by various RF-reactive regions. Strong support for this concept was obtained using rabbit antisera as well as mouse mAbs to individual CH3, CH2 or β2m RF-reactive peptides. Major cross-reactivity was demonstrated between most of the 14 different CH3, CH2, or β2m RF-reactive peptides using individual anti-epitope antibodies. Molecular modelling studies of these peptides showed striking similarities in three-dimensional shape among many RF-reactive peptides. Main-chain atoms rather than side chains seemed to contribute most directly to conformational similarity. Molecular simulation studies on control peptides showed no conformational similarities with RF-reactive peptides. Our studies indicate that autoantibodies such as RF recognize main-chain conformations of reactive epitopes and react with a number of antigenic determinants of quite different primary sequence but similar main chain conformations.
Transformed B cells making monoclonal IgM-λ anti-PR3 antibody WGH1 from a patient with Wegener's ... more Transformed B cells making monoclonal IgM-λ anti-PR3 antibody WGH1 from a patient with Wegener's granulomatosis were used to prepare mRNA and synthesize cDNA. PCR primers for human μ and λ chains were then employed to amplify heavy- and light-chain V-regions followed by cloning into pCR2-1 vector and sequencing. Molecular modeling of VH regions employed knowledge-based homology modeling to obtain minimum energy conformation. The VH sequence was subgroup III with marked overall homology to VH1.9III. The VHCDR3 region of WGH1 was unique, consisting of 21 amino acid residues which included seven tyrosines as well as three negatively charged aspartic acid residues. The VL region was subgroup II with a negatively charged glutamic acid at position 100 in CDR3. Molecular modeling of VH revealed a major conformational difference in the shape of CDR3 compared with other antibodies for which three-dimensional structures have been determined. Monoclonal antibody WGH1 reacting with PR3 (a highly positively charged molecule) shows a unique reactive cassette within VHCDR3 with a number of negatively charged aspartic acid residues. WGH1 VHCDR3 contains a loop which shows a major projection not usually recorded in other previously studied antibody molecules.
ABSTRACT This paper presents an algorithm for multiple alignment of sequences of proteins and nuc... more ABSTRACT This paper presents an algorithm for multiple alignment of sequences of proteins and nucleic acids on loosely-coupled MIMD machines. An inherently parallel algorithm is devised and implemented on a transputer-based multiprocessor platform. The ...
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Papers by Urmila Kulkarni-Kale