Unveiling potential repurposed drug candidates for Plasmodium falciparum through in silico evaluation: A synergy of structure-based approaches, structure prediction, and molecular dynamics simulations

The rise of drug resistance in Plasmodium falciparum, rendering current treatments ineffective, has hindered efforts to eliminate malaria. To address this issue, the study employed a combination of Systems Biology approach and a structure-based pharmacophore method to identify a target against P. falciparum. Through text mining, 448 genes were extracted, and it was discovered that plasmepsins, found in the Plasmodium genus, play a crucial role in the parasite's survival. The metabolic pathways of these proteins were determined using the PlasmoDB genomic database and recreated using CellDesigner 4.4.2. To identify a potent target, Plasmepsin V (PF13_0133) was selected and examined for protein-protein interactions (PPIs) using the STRING Database. Topological analysis and global-based methods identified PF13_0133 as having the highest centrality. Moreover, the static protein knockout PPIs demonstrated the essentiality of PF13_0133 in the modeled network. Due to the unavailability of the protein's crystal structure, it was modeled and subjected to a molecular dynamics simulation study. The structure-based pharmacophore modeling utilized the modeled PF13_0133 (PfPMV), generating 10 pharmacophore hypotheses with a library of active and inactive compounds against PfPMV. Through virtual screening, two potential candidates, hesperidin and rutin, were identified as potential drugs which may be repurposed as potential anti-malarial agents.

Expanding the therapeutic arsenal against cancer: a computational investigation of hybrid xanthone derivatives as selective Topoisomerase 2α ATPase inhibitors

The DNA topoisomerase II (topo II) enzyme plays an important role in the replication, recombination, and repair of DNA. Despite their widespread applications in cancer therapy, new, selective, and potent topo II inhibitors with better pharmaceutical profiles are needed to handle drug resistance and severe adverse effects. In this respect, an array of 36 new anticancer compounds was designed based on a Xanthone core tethered to multifunctional Pyridine-amines and Imidazole scaffold via alkyl chain linkers. An integrated in silico approach was used to understand the structural basis and mechanism of inhibition of the hybrid xanthone derivatives. In this study, we established an initial virtual screening workflow based on pharmacophore mapping, docking, and cancer target association to validate the target selection process. Next, a simulation-based docking was conducted along with pharmacokinetic analysis to filter out the five best compounds (7, 10, 25, 27, and 30) having binding energies within the range of -60.45 to -40.97 kcal/mol. The screened compounds were further subjected to molecular dynamics simulation for 200 ns followed by MM-GBSA and ligand properties analysis to assess the stability and binding affinity to hTOP2α. The top-ranking hits 3,7-bis(3-(2-aminopyridin-3-ylhydroxy)propoxy)-1-hydroxy-9H-xanthen-9-one (ligand 7) and 3,8-bis(3-(2-aminopyridin-3-ylhydroxy)propoxy)-1-hydroxy-9H-xanthen-9-one (ligand 25) were found to have no toxicity, optimum pharmacokinetic and, DFT properties and stable intermolecular interactions with the active site of hTopo IIα protein. In conclusion, further in vitro and in vivo experimental validation of the identified lead molecules is warranted for the discovery of new human Topoisomerase 2 alpha inhibitors.Communicated by Ramaswamy H. Sarma.

An Integrative Approach to Study the Inhibition of Providencia vermicola FabD Using C2-Quaternary Indolinones

Background

The present study investigates the potential bioactivity of twelve experimentally designed C-2 quaternary indolinones against Providencia spp., a bacterial group of the Enterobacteriaceae family known to cause urinary tract infections. The study aims to provide insights into the bioactive properties of the investigated compounds and their potential use in developing novel treatments against Providencia spp. The experimental design of indolinones, combined with their unique chemical structure, makes them attractive candidates for further investigation. The results of this research may contribute to the development of novel therapeutic agents to combat Providencia spp. infections.

Methods

The synthesized indolinones (moL1-moL12) are evaluated to identify any superior activity, particularly focusing on moL12, which possesses aza functionality. The antimicrobial activities of all twelve compounds are tested in triplicates against six different Gram-positive and Gram-negative organisms, including P. vermicola (P<0.05). Computational methods have been employed to assess the pharmacokinetic properties of the compounds.

Results

Among the synthesized indolinones, moL12 exhibits superior activity compared to the other compounds with similar skeleton but different functional moieties. All six strains tested, including P. vermicola, demonstrated sensitivity to moL12. Computational studies support the pharmacokinetic properties of moL12, indicating acceptable absorption, distribution, metabolism, excretion, and toxicity characteristics.

Conclusion

Utilizing the PPI approach, we have identified a promising target, FabD, in Gram-negative bacteria. Our analysis has shown that moL12 exhibits significant potential in binding with FabD, thereby, might inhibit cell wall formation, and display superior antimicrobial activity compared to other compounds. Consequently, moL12 may be a potential therapeutic agent that could be used to combat urinary tract infections caused by Providencia spp. The findings of this research hold significant promise for the development of new and effective treatments for bacterial infections.

Revelation of potential drug targets of luteolin in Plasmodium falciparum through multi-target molecular dynamics simulation studies

In-silico techniques offer a fast, accurate, reliable, and economical approach to studying the molecular interactions between compounds and proteins. In this study, our main aim is to use in-silico techniques as a rational approach for the prediction of the molecular drug targets for luteolin against Plasmodium falciparum. Multi-target molecular docking, 100 nanoseconds (ns) molecular dynamics (MD) simulations, and Molecular Mechanics-Generalized Born Surface Area (MM-GBSA) binding free energy calculations were carried out for luteolin against dihydrofolate reductase thymidylate synthase (PfDHFR-TS), dihydroorotate dehydrogenase (PfDHODH), and falcipain-2. The native ligands of each protein were used as a reference to evaluate the performance of luteolin. Luteolin outperformed the native ligands of all proteins at molecular docking and MD simulations studies. However, in the MM-GBSA calculations, luteolin outperformed the native ligand of only PfDHFR-TS but not PfDHODH and falcipain-2. Among the studied proteins, the in-silico approach predicted PfDHFR-TS as the most favorable drug target for luteolin.Communicated by Ramaswamy H. Sarma.

Target specific inhibition of West Nile virus envelope glycoprotein and methyltransferase using phytocompounds: an in silico strategy leveraging molecular docking and dynamics simulation

Mosquitoes are the primary vector for West Nile virus, a flavivirus. The virus's ability to infiltrate and establish itself in increasing numbers of nations has made it a persistent threat to public health worldwide. Despite the widespread occurrence of this potentially fatal disease, no effective treatment options are currently on the market. As a result, there is an immediate need for the research and development of novel pharmaceuticals. To begin, molecular docking was performed on two possible West Nile virus target proteins using a panel of twelve natural chemicals, including Apigenin, Resveratrol, Hesperetin, Fungisterol, Lucidone, Ganoderic acid, Curcumin, Kaempferol, Cholic acid, Chlorogenic acid, Pinocembrin, and Sanguinarine. West Nile virus methyltransferase (PDB ID: 2OY0) binding affinities varied from -7.4 to -8.3 kcal/mol, whereas West Nile virus envelope glycoprotein affinities ranged from -6.2 to -8.1 kcal/mol (PDB ID: 2I69). Second, substances with larger molecular weights are less likely to be unhappy with the Lipinski rule. Hence, additional research was carried out without regard to molecular weight. In addition, compounds 01, 02, 03, 05, 06, 07, 08, 09, 10 and 11 are more soluble in water than compound 04 is. Besides, based on maximum binding affinity, best three compounds (Apigenin, Curcumin, and Ganoderic Acid) has been carried out molecular dynamic simulation (MDs) at 100 ns to determine their stability. The MDs data is also reported that these mentioned molecules are highly stable. Finally, advanced principal component analysis (PCA), dynamics cross-correlation matrices (DCCM) analysis, binding free energy and dynamic cross correlation matrix (DCCM) theoretical study is also included to established mentioned phytochemical as a potential drug candidate. Research has indicated that the aforementioned natural substances may be an effective tool in the battle against the dangerous West Nile virus. This study aims to locate a bioactive natural component that might be used as a pharmaceutical.

Unsupervised machine learning, QSAR modelling and web tool development for streamlining the lead identification process of antimalarial flavonoids

Identification of lead compounds with the traditional laboratory approach is expensive and time-consuming. Nowadays, in silico techniques have emerged as a promising approach for lead identification. In this study, we aim to develop robust and predictive 2D-QSAR models to identify lead flavonoids by predicting the IC₅₀ against Plasmodium falciparum. We applied machine learning algorithms (Principal component analysis followed by K-means clustering) and Pearson correlation analysis to select 9 molecular descriptors (MDs) for model building. We selected and validated the three best QSAR models after execution of multiple linear regression (MLR) 100 times with different combinations of MDs. The developed models have fulfilled the five principles for QSAR models as specified by the Organization for Economic Co-operation and Development. The outcome of the study is a reliable and sustainable in silico method of IC₅₀ (Mean ± SD) prediction that will positively impact the antimalarial drug development process by reducing the money and time required to identify potential antimalarial lead compounds from the class of flavonoids. We also developed a web tool (JazQSAR, https://etflin.com/news/4) to offer an easily accessible platform for the developed QSAR models.

Nano-functionalization and evaluation of antimicrobial activity of Tinospora cordifolia against the TolB protein of Pseudomonas aeruginosa - An antibacterial and computational study

Introduction

Antibacterial drug resistance, brought on by the overuse of antibiotics, is one of the biggest threats to human health. It is crucial to consider cutting-edge strategies, such as herbal remedies, to control multidrug-resistant (MDR) bacteria.

Methods

This study evaluated the phytochemical, antioxidant and antibacterial properties of the various Tinospora cordifolia extracts. Functionalization of the isolated active compound was done using gold (Au) and silver (Ag) nanoparticles (NPs). Further, to understand the interaction of the isolated class, Cordifolisides, with its target, various in-silico methods were used.

Results and Discussion

The plant was reported from the Charaideo district of Assam, whose methanolic stem extract showed the maximum activity towards the nosocomial pathogen Pseudomonas aeruginosa. Consequently, the active compound was isolated and characterized as belonging to the class Cordifoliside using NMR. The AuNPs and AgNPs functionalized isolates showed enhanced antimicrobial activity against P. aeruginosa compared to the unfunctionalized isolate. The most reactive compound, Cordifoliside C was determined using Density Functional Theory (DFT) analysis, whose interactions with the TolB protein were studied using molecular docking methods, which revealed good binding interactions of Cordifoliside C with the TolB protein.

Conclusion

This study offers enormous potential for drug design and might be used as a pipeline to address the urgent problem of multidrug-resistance in bacteria. Graphical Abstract.

Towards designing of a potential new HIV-1 protease inhibitor using QSAR study in combination with Molecular docking and Molecular dynamics simulations

Human Immunodeficiency Virus type 1 protease (HIV-1 PR) is one of the most challenging targets of antiretroviral therapy used in the treatment of AIDS-infected people. The performance of protease inhibitors (PIs) is limited by the development of protease mutations that can promote resistance to the treatment. The current study was carried out using statistics and bioinformatics tools. A series of thirty-three compounds with known enzymatic inhibitory activities against HIV-1 protease was used in this paper to build a mathematical model relating the structure to the biological activity. These compounds were designed by software; their descriptors were computed using various tools, such as Gaussian, Chem3D, ChemSketch and MarvinSketch. Computational methods generated the best model based on its statistical parameters. The model's applicability domain (AD) was elaborated. Furthermore, one compound has been proposed as efficient against HIV-1 protease with comparable biological activity to the existing ones; this drug candidate was evaluated using ADMET properties and Lipinski's rule. Molecular Docking performed on Wild Type, and Mutant Type HIV-1 proteases allowed the investigation of the interaction types displayed between the proteases and the ligands, Darunavir (DRV) and the new drug (ND). Molecular dynamics simulation was also used in order to investigate the complexes' stability allowing a comparative study on the performance of both ligands (DRV & ND). Our study suggested that the new molecule showed comparable results to that of darunavir and maybe used for further experimental studies. Our study may also be used as pipeline to search and design new potential inhibitors of HIV-1 proteases.

Development of a rapid loop-mediated isothermal amplification (LAMP) assay for visual detection of porcine parvovirus (PPV) and its application

Porcine parvovirus (PPV) infection is one of the most important causes of reproductive failure in pigs impacting the piggery industry globally with huge economic losses. A cost-effective, simple, rapid, specific, and sensitive method is critical for monitoring PPV infection on pig farms. The main aim of the present study was to develop and evaluate a loop-mediated isothermal amplification (LAMP) assay for rapid visual detection of porcine parvovirus (PPV) in pigs. A set of six LAMP primers including two outer primers, two inner primers, and two loop primers were designed utilizing the conserved region of capsid protein VP2 gene sequences of PPV and was applied for detection of PPV from porcine samples. Time and temperature conditions for amplification of PPV genes were optimized to be 30 min at 63 °C. The developed assay was ten-fold more sensitive than conventional PCR with analytical sensitivity of 20 pg and 200 pg, respectively. This is the first report of detection of PPV by LAMP assay from India. The assay did not cross-react with porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV), or classical swine fever virus (CSFV). The LAMP assay was assembled into a LAMP assay kit of 20 reactions and was validated in different laboratories in India. The newly developed LAMP assay was proved to be a specific, sensitive, rapid, and simple method for visual detection of PPV which does not require even costly equipments for performing the test. It complements and extends previous methods for PPV detection and provides an alternative approach for detection of PPV.

Virulence associated gene profiling and antimicrobial resistance pattern of Streptococcus suis isolated from clinically healthy pigs from North East India

This study revealed the prevalence of Streptococcus suis in 20·39% clinically healthy pigs from North East India. All these isolates were screened for the presence of virulence- associated genes such as suilysin (sly), muramidase released protein (mrp), extracellular protein factor (epf) and arginine deiminase (arcA). Of these 62 isolates, 29 isolates carried mrp gene, 17 isolates carried sly gene, 57 isolates carried arcA gene, whereas all isolates were negative for epf gene. The most prevalent genotype was mrp^- sly^- epf^- arcA⁺ (45·16%) followed by genotypes mrp⁺ sly^- epf^- arcA⁺ (27·41%), mrp⁺ sly⁺ epf^- arcA⁺ (19·35%) and mrp^- sly⁺ epf^- arcA^- (8·06%). High frequency of resistance was observed for antimicrobials such as tetracycline (93·54%), clindamycin (91·93%), co-trimoxazole (88·70%) and erythromycin (85·48%). Antimicrobial resistance patterns of the S. suis isolates revealed 16 resistance groups (R1 to R16), where 93·54% isolates showed multi-drug resistance (≥3 antimicrobial agents). It has also been observed that 57 (91·93%) isolates were resistant to at least four antimicrobials. The most predominant resistance pattern observed was CD-COT-E-TE, which accounted for 38·70% of the isolates. The occurrence of relatively high levels of resistance of S. suis to some antimicrobials (e.g., macrolides, tetracyclines, and sulphonamides) as observed in this study may represent a human health concern. In addition, a relatively higher percentage of S. suis isolated from clinically healthy pigs indicates a carrier status with risk of dissemination to other pigs in the herd as well as to humans.

Development and application of a triplex-PCR assay for rapid detection of methicillin-resistant Staphylococcus aureus from pigs

A triplex-PCR assay was developed and evaluated for rapid detection of methicillin-resistant Staphylococcus aureus (MRSA) recovered from various biological samples of pig. Three sets of primers were designed to target mecA, 16S rRNA and nuc genes of MRSA. The specific amplification generated three bands on agarose gel, with sizes 280 bp for mecA, 654 bp for 16S rRNA and 481 bp for nuc, respectively. A potential advantage of the PCR assay is its sensitivity with a detection limit of 10²  CFU per ml of bacteria. In all, 79 MRSA isolates recovered from various samples of pigs were subjected to the amplification by the triplex-PCR assay and all the isolates yielded three bands corresponding to the three genes under this study. No false-positive amplification was observed, indicating the high specificity of the developed triplex-PCR assay. This assay will be a useful and powerful method for differentiation of MRSA from methicillin-sensitive S. aureus, coagulase-negative methicillin-resistant staphylococci and coagulase-negative methicillin-sensitive staphylococci.

Haemato-biochemical alterations and oxidative stress associated with naturally occurring porcine circovirus2 infection in pigs

Porcine circovirus2 (PCV2) infection in pigs is one of the major causes of economic loss to the farmers in terms of low production, slow growth and increase post-weaning mortality rate. The effect of PCV2 infection on haemogram, serum biochemical profile and oxidant/anti-oxidant status is not well established in pigs. In the present study, haemogram, serum biochemical profile and oxidant/anti-oxidant status were assessed in pigs confirmed positive for PCV2 infections as evidenced by commercially available enzyme-linked immunosorbent assay kit (n = 151) and polymerase chain reaction (PCR) (n = 42) among a total of 306 number of pigs included in the study. Non-infected healthy pigs (n = 6) served as healthy control. The total erythrocyte count (TEC), haemoglobin (Hb), packed cell volume (PCV), total leukocyte count (TLC), differential leukocyte count (DLC) and thrombocyte count were measured. The levels of total protein, albumin, globulin, total bilirubin, direct bilirubin, blood urea nitrogen (BUN), creatinine and glucose and enzymes viz. alanine transaminase (ALT), aspartate transaminase (AST), gamma-glutamyl transferase (GGT) and alkaline phosphatase (ALP) were measured. Oxidative stress indicators such as plasma malondialdehyde (MDA) and total anti-oxidant activity (TAOA) were measured using commercially available kits. The mean values of TLC, lymphocytes and thrombocyte count were significantly (P < 0.05) low in PCV2-infected pigs. The levels of globulin, AST, GGT, BUN and creatinine were significantly increased (P < 0.05) whereas levels of albumin and glucose significantly (P < 0.05) decreased in PCV2-infected pigs. The significant increase (P < 0.05) in MDA level and significant decrease (P < 0.05) in TAOA level were noticed in PCV2-infected animals as compared with healthy control. The present study supports immunosuppression, possible multiple organ damage and oxidative stress associated with naturally occurring PCV2 infection in pigs. Timely vaccination and managemental practices can reduce PCV2 infection in farms. In spite of many research studies, there is still paucity of detailed systemic study on haemato-biochemical alteration and oxidative stress associated with PCV2 infection.

The effect of temperature, composition and alcohols on the microstructures of catanionic mixtures of sodium dodecylsulfate and cetyltrimethylammonium bromide in water

The influence of mixing protocol, composition, temperature, ageing and added alcohols on the characteristics of the microstructures of sodium dodecylsulfate (SDS) + cetyltrimethylammonium bromide (CTAB) mixtures has been investigated in this paper. In this catanionic mixture (1 weight% total surfactant content) temperature induced microstructural transition occurs, which is (i) a micelle-to-vesicle transition (MVT) if α_SDS (mole fraction of SDS) = 0.7, 0.8 or 0.9 and (ii) a vesicle-to-micelle transition (VMT) if α_SDS = 0.1, 0.2 or 0.3. In the mixture of α_SDS = 0.7, specific conductivity and dynamic light scattering measurements also support the occurrence of MVT. Transition electron microscopy and small angle neutron scattering measurements were also made to assess the characteristics of the microstructures. Alcohols added to the mixture of α_SDS = 0.7 reduced the size of the vesicle, while only monohydric alcohols suppressed the temperature induced transition indicating that the number and location of -OH groups of the alcohols have a dramatic modulating influence on the structural transition occurring in catanionic mixtures. The influence of the alcohols is explained in terms of changes produced in the dielectric constant and hydrophobicity of the medium.

Protein-Ligand Docking Methodologies and Its Application in Drug Discovery

Molecular docking is a key tool in structural biology and computer-assisted drug design. Molecular docking is a method which predicts the preferred orientation of a ligand when bound in an active site to form a stable complex. It is the most common method used as a structure-based drug design. Here, the authors intend to discuss the various types of docking methods and their development and applications in modern drug discovery. The important basic theories such as sampling algorithm and scoring functions have been discussed briefly. The performances of the different available docking software have also been discussed. This chapter also includes some application examples of docking studies in modern drug discovery such as targeted drug delivery using carbon nanotubes, docking of nucleic acids to find the binding modes and a comparative study between high-throughput screening and structure-based virtual screening.

In silico approaches and proportional odds model towards identifying selective ADAM17 inhibitors from anti-inflammatory natural molecules

ADAM metallopeptidase domain 17 (ADAM17) is an attractive target for the development of new anti-inflammatory drugs. We aimed to identify selective inhibitors of ADAM17 against matrix metalloproteinase enzymes (MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-13, and MMP-16) which have substantial structural similarity. Target proteins were docked with 29 anti-inflammatory natural molecule ligands and a known selective inhibitor IK682. The ligands were screened based on Lipinski rules, interaction with the ADAM17 active site cavity, and then ranked using the proportional odds model multinomial logistic regression. Silymarin was the most selective inhibitor of ADAM17 exhibiting H-bonding with Glu 406, Gly 349, Glu 398, Asn 447, Tyr 433, and Lys 432. Molecular dynamics simulations were carried out for 10ns. The root mean square deviation (RMSD), root mean squared fluctuations (RMSF), radius of gyration (Rg), solvent accessible surface area (SASA), and H-bonding indicated the induced metastability. A comparison of the principal component analysis revealed that the silymarin complex also explored lesser region compared to IK682 complex. A control study on ADAM17 protein (2OI0) is included. These observations present silymarin (widely present in plants such as milk thistle (Silybum maianum), wild artichokes (Cynara cardunculus), turmeric (Curcuma longa) roots, coriander (Coriandrum sativum) seeds, etc.) as a promising natural template for development of ADAM17 selective drugs.

Si-Doped single-walled carbon nanotubes interacting with isoniazid-a density functional and molecular docking study

The interaction of antitubercular drug isoniazid (INH), with pristine and Si-doped (5,5) and (9,0) single-walled carbon nanotubes (SWNTs) have been reported.

Anti-tubercular drug development: computational strategies to identify potential compounds

InhA is an attractive target to combat tuberculosis (TB), which is targeted by many pro-drugs (isoniazid, etc.) and drugs such as triclosan. However, triclosan is less useful as an antitubercular drug due to its low bioavailability and therefore, in order to overcome this difficulty, many derivatives of triclosan were prepared. Here, we have combined various computational techniques to virtually screen out four potential triclosan derivatives. Molecular docking methods have been employed to screen out 32 out of 62 triclosan derivatives considering the mode of binding and the top re-rank scores. A comparative study on the chemical properties of triclosan and some of its derivatives has been performed using density functional theory (DFT) calculations. DFT based global reactivity descriptors (GRD), such as hardness, chemical potential, chemical softness, electrophilicity index, Fukui function, and local philicity calculated at the optimized geometries were used to investigate the usefulness of these descriptors for understanding the reactive nature and sites of the molecules. QSAR equations were built using these descriptors considering these 32 compounds. Four common compounds showing the best correlation and the best docking scores were considered for the ADMET property calculations and their dynamical movements have been studied using molecular dynamics simulations. Our results showed that these four compounds are chemically more active than triclosan and have the potential to inhibit the Mycobacterium tuberculosis enoyl acyl carrier protein reductase. This work shows that combination of different computational techniques may help to screen out potential drug candidates from a list of possible ones.

Development of a novel multiplex PCR assay for rapid detection of virulence associated genes of Pasteurella multocida from pigs

As the pathogenicity of Pasteurella multocida is associated with various virulence factors (VFs), the aim of the study was to develop a novel multiplex PCR (m-PCR) assay for the rapid detection of important virulence associated genes (VAGs) of P. multocida isolates from pigs. The target recognized VFs used in the study were diverse adhesins (ptfA and pfhA), toxins (toxA), siderophores (tonB and hgbA), sialidases (nanB, nanH) and outer membrane proteins (ompA, ompH, oma87 and plpB). The primers for the genes encoding these VFs were designed by primer3 software (http://bioinfo.ut.ee/primer3-0.4.0/) using gene sequences available in Genbank. The detection limit of the developed assay was 10(2)  CFU ml(-1) . The m-PCR did not produce any nonspecific amplification products when tested against Bordetella bronchiseptica which also commonly infects pigs. We applied m-PCR to the field samples, and the results obtained were the same as the single PCR results. The developed assay would be very useful for veterinary diagnostic laboratories and for others interested in the rapid virulence profiling of porcine P. multocida isolates circulating in the piggeries.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study reports the development and evaluation of a novel multiplex PCR assay for the rapid detection of 11 important VAGs of Pasteurella multocida isolates from pigs. Rapid and simultaneous detection of recognized VFs of the organism are essential to know the virulo-types of P. multocida isolates circulating in the piggeries. The developed novel assay will be very useful for the rapid detection of VAGs of P. multocida isolates from pigs.

Predominance of genotype 1.1 and emergence of genotype 2.2 classical swine fever viruses in north-eastern region of India

Classical swine fever (CSF) is a highly contagious and the most important disease of pigs worldwide.CSF is enzootic in pig herds in India and continues to cause huge economic losses to pig farmers. Nearly 40% of the total pig population of India is present in the north-eastern (NE) states where pig husbandry plays an important role in the socio-economic development. Pigs reared in the backyards are the only source of livelihood for a majority of poor tribal population in the region. Hardly any CSF vaccination is currently being undertaken in the unorganized pig farming in the NE region due to economic reasons and vaccine unavailability. A thorough understanding of the current epidemiological status of CSF is essential for the effective control of the disease in the NE region. Hence, we carried out molecular characterization of CSFV isolates from field outbreaks during 2011-2012 in the entire north-eastern region of India to establish the genetic groups of prevalent CSF viruses in the region. A total of 17 CSFV isolates obtained from different parts of the NE region were characterized by comparing the sequences of three partial genomic regions of the virus, that is 150 nt of 5' UTR, 190 nt of E2 and 409 nt of NS5B. Of the 17 CSFV isolates, 15 isolates belonged to 1.1 (88.2%) and two isolates (11.8%) belonged to 2.2 subgenogroup. The genogroup 2.2 CSFV were associated with outbreaks in Arunachal Pradesh that shares international borders with Bhutan, Myanmar and China. Genogroup 2.2 CSFV isolated in the present study shared high level of sequence similarity with 2.2 viruses form China, raising the possibility of virus incursion from this region. In summary, we found a continued predominance of 1.1 subgroup and an emergence of 2.2 subgroup CSFV in NE region of India.

Detection of heat-stable and heat-labile enterotoxin genes of Escherichia coli in diarrhoeic faecal samples of mithun (Bos frontalis) calves by polymerase chain reaction

AIMS

To find out the prevalence of different serogroups of Escherichia coli (E. coli) and to detect heat-stable (ST) and heat-labile (LT) enterotoxin genes of enterotoxigenic E. coli (ETEC) from the faeces of mithun calves with diarrhoea.

METHODS AND RESULTS

Faecal samples obtained from 65 diarrhoeic mithun calves of under 2 months of age were examined for E. coli using polymerase chain reaction (PCR). Fifty-four E. coli isolates were obtained from those samples, which belonged to 38 different serogroups. Out of 54 isolates tested by PCR, two isolates (3.70%) belonging to serogroups O26 and O55 were found to possess gene that code for ST enterotoxin and one isolate (1.85%) belonging to serogroup O125 was found to carry LT enterotoxin gene.

CONCLUSIONS

Escherichia coli isolates from diarrhoeic mithun calves were found to possess ST and LT enterotoxin genes, which are designated as ETEC, and these isolates can be detected through PCR using specific primers.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study reports the isolation of ETEC possessing ST and LT enterotoxin genes for the first time and ETEC could be a cause of diarrhoea in mithun calves leading to calf mortality.

Bluetongue infection rate in mithun (Bos frontalis) in the north-eastern upland region of India

Studies conducted on 106 mithun at the National Research Centre on Mithun and 66 free-ranging mithun in Nagaland, India, revealed an infection rate with bluetongue virus of 86%, using a commercially available competitive enzyme-linked immunosorbent assay. Animals were grouped according to their age: 36 of 1 to 2 years of age, 50 of 2 to 4 years of age and 86 aged 4 years and over. The highest infection rate (98%) was found in mithun > 4 years old and the lowest (58%) in those 1 to 2 years old. No statistically significant difference was observed between infection rates of males (89%) and females (85%). The infection rate was higher (95%) in free-ranging mithun than in mithun kept under a semi-intensive system (80%). This is the first report of serological evidence of antibodies to bluetongue virus in mithun. The possible role of vectors in the epidemiology of bluetongue virus infection in mithun is discussed briefly.

Seroprevalence of Toxoplasma gondii antibodies in free-ranging mithuns (Bos frontalis) from India

Studies conducted on free-ranging mithuns of Nagaland, India revealed that the overall seroprevalence of antibodies to Toxoplasma gondii in mithun was 42% (95% CI = 33-51) when detected by modified direct agglutination test. Highest (prevalence = 57%, 95% CI = 43-71) seroprevalence was found in mithuns above 3 years of age and the lowest (prevalence = 18%, 95% CI =4-32) in mithuns of 1-2 years old. No statistically significant difference was observed between male (prevalence = 40%, 95% CI = 26-54) and female (prevalence = 44%, 95% CI = 31-57) seroprevalences. The study also revealed that the maximum number (57%) of animals with the highest titre (1 : 3200) were above 3 years of age. This is the first serological survey for Toxoplasma gondii antibodies in free-ranging mithuns from India.

Serological evidence of Neospora caninum infection in mithun (Bos frontalis) from India

Studies conducted on mithuns maintained at National Research Centre on mithun, Indian Council of Agricultural Research (ICAR), Nagaland, India and mithuns found in free-ranging condition of Nagaland revealed that the overall prevalence of antibodies to Neospora caninum in mithun was 10% (95% CI=5-15) when detected by a commercially available competitive enzyme-linked immunosorbent assay test. Highest (prevalence rate=16, 95% CI=8-24) seroprevalence was found in mithuns above 3 years of age and lowest (prevalence rate=2, 95% CI=0-6) in mithuns of 2-12 months old. No statistically significant difference was observed between male (prevalence rate=7, 95% CI=0-14) and female (prevalence rate=12, 95% CI=6-18) seroprevalences. The seroprevalence was found to be higher (prevalence rate=20, 95% CI=9-31) in mithuns found in free-ranging condition in comparison to mithuns kept in semi-intensive system (prevalence rate=5, 95% CI=1-9). This is probably the first report on serological evidence of N. caninum infection in mithun. The possible role of sylvatic fauna in the epidemiology of N. caninum infection mithun is also discussed in brief.

Serological evidence of coronavirus infection in mithuns (Bos frontalis) from India

Studies conducted on mithuns at the National Research Centre on Mithun, and mithuns found in free-ranging conditions in Nagaland, India, revealed that the overall prevalence of antibodies to coronavirus was 80% (95% confidence interval [CI] 77-83) when detected by a commercially available enzyme-linked immunosorbent assay. The highest seroprevalence (92%; 95% CI 89-95) was found in mithuns above three years of age, and the lowest (53%; 95% CI 36-70) in mithuns of 7 to 12 months old (P = 0.00005). The study also revealed a higher degree of positivity (++++) in mithuns above three years old than in those below one year. No statistically significant difference in seroprevalence was observed between male (80%; 95% CI 75-85) and female mithuns (80%; 95% CI 76-84). The seroprevalence was found to be higher (92%; 95% CI 89-95) in mithuns reared in semi-intensive systems compared with those kept under free-ranging conditions (56%; 95% CI 49-63; P = 0.003). This is probably the first serological evidence of coronavirus infection in mithuns. The possible role of adults in the epidemiology of coronavirus infection in mithuns is also discussed.

Prevalence of Cryptosporidium parvum in mithuns (Bos frontalis) from India

Systematic examination of faecal samples from mithuns maintained at the National Research Centre on Mithun, Indian Council of Agricultural Research (ICAR), Nagaland, India and mithuns found in free-ranging condition of Nagaland, by using a commercially available enzyme-linked immunosorbent assay kit, revealed that the overall prevalence of Cryptosporidium parvum in mithun was 56% (95% CI=48-64). Highest (prevalence rate=81, 95% CI=67-95) prevalence was found in mithuns of 1-6 months of age and lowest (prevalence rate=42, 95% CI=31-53) in mithuns above 2 years of age. The prevalence was found to be higher (94%) in diarrhoeic animals in comparison to non-diarrhoeic group (51%). No statistically significant difference was observed between male (prevalence rate=61, 95% CI=48-74) and female (prevalence rate=53, 95% CI=43-63) prevalences. The prevalence was found to be higher (prevalence rate=64, 95% CI=55-73) in mithuns kept in semi-intensive system than mithuns found in free-ranging condition (prevalence rate=40, 95% CI=27-53). The risk factor that may play a pivotal role in the epidemiology of cryptosporidiosis in mithun is also discussed in brief. The zoonotic implication of the disease is also discussed. This is probably the first report on prevalence of Cryptosporidium parvum in mithun.

Seroprevalence of Toxoplasma gondii antibodies in captive mithuns (Bos frontalis) from India

One hundred and four mithuns from India were tested for serum antibodies to Toxoplasma gondii by modified direct agglutination test. The overall prevalence of T. gondii antibodies in mithun was 28% (95% CI=19-37). Highest (prevalence rate=46, 95% CI=30-62) seroprevalence of T. gondii antibodies was found in mithuns above 3 years of age and lowest (prevalence rate=14, 95% CI=1-27) in mithuns of 6 months-1 year old. No statistically significant difference was observed between male (prevalence rate=23, 95% CI=10-36) and female (prevalence rate=31, 95% CI=20-42) seroprevalences (P=0.53). Significant difference was observed in the seroprevalence of T. gondii antibodies in mithuns of different strains with the highest (48%) seroprevalence recorded in Arunachal and lowest (14%) in Mizoram strain. The seroprevalence was higher in farm located at lower altitude (305 m a.s.l.) than the farm located at higher altitude (2134 m a.s.l.). This is the first serologic survey for T. gondii antibodies performed on mithuns from India.

Seroprevalence of brucellosis in mithuns (Bos frontalis) in India

Studies conducted on the seroprevalence of brucellosis in 98 mithuns maintained at the National Research Centre on Mithun, Nagaland, India revealed that the number of animals found positive for brucellosis in avidin-biotin enzyme-linked-immunosorbent assay, standard tube-agglutination test and Rose-Bengal plate test were 34, 20 and 11%, respectively. Highest prevalence of brucellosis was observed in the Mizoram mithun strain. The relative sensitivity and specificity of the standard tube-agglutination test were 61 and 100%, respectively; the corresponding values of the Rose-Bengal plate test were 33 and 100%, respectively.

Seroprevalence of infectious bovine rhinotracheitis in mithun (Bos frontalis) in India

A preliminary study on the seroprevalence of infectious bovine rhinotracheitis (IBR) in different strains of mithun maintained atthe National Research Centre on Mithun, Nagaland, India, revealed that the overall prevalence of IBR in these mithun was 19%. This paper examines the results of that preliminary study. To the knowledge of the authors, this is the first report on the seroprevalence of IBR in mithun in India. The highest prevalence of IBR was observed in mithun found in Arunachal Pradesh (38.46%), followed by those found in Mizoram (18.18%) and Nagaland (15.15%). None of the animals from Manipur were found to test positive for antibodies against IBR. The sex of the animal had no influence on IBR prevalence. The prevalence was found to be highest (27.03%) in mithun above three years of age and lowest (7.69%) in mithun aged between six months and one year. The prevalence of IBR was found to be 88.9% in breeding mithun bulls. In this paper, the authors briefly discuss the possible roles of feral fauna and domestic livestock in the transmission of this disease to mithun and vice versa. Various measures that may help in the prevention and control of IBR in mithun are also surveyed. However, it should be emphasised that this study is a preliminary one, and the authors are currently engaged in further research.