Role of narL gene in the pathogenesis of Salmonella Typhimurium

Salmonella Typhimurium (STM) is a facultative anaerobe and one of the causative agents of nontyphoidal salmonellosis (NTS). Its anaerobic metabolism is enabled under the hypoxic environment that is encountered inside macrophages and the gut lumen of the host. In both of these niches, free radicals and oxidative intermediates are released by neutrophils as an inflammatory response. These chemical species further undergo reactions to produce nitrate, which is preferably taken up by STM as an electron acceptor in the absence of oxygen. NarL, the response regulator of the two-component regulatory system NarX/L, and a transcription factor, gets activated under anaerobic nitrate-rich conditions and upregulates the nitrate reduction during anaerobic respiration of STM. To understand the role of NarL in the pathogenesis of STM, we generated a narL-knockout (STM:ΔnarL) as well as a narL-complemented strain of STM. Anaerobically, the mutant displayed no growth defect but a significant attenuation in the swimming (26%) and swarming (61%) motility, and biofilm-forming ability (73%) in vitro, while these morphotypes got rescued upon genetic complementation. We also observed a downregulation in the expression of genes associated with nitrate reduction (narG) and biofilm formation (csgA and csgD) in anaerobically grown STM:ΔnarL. As compared with wild STM, narL mutant exhibited a threefold reduction in the intracellular replication in both intestinal epithelial cells (INT- 407) and monocyte-derived macrophages of poultry origin. Further, in vivo competitive assay in the liver and spleen of the murine model showed a competitive index of 0.48 ± 0.58 and 0.403668 ± 0.32, respectively, for STM:ΔnarL.

Pathomorphology, immunohistochemical, and molecular detection of an atypical porcine dermatitis and nephropathy syndrome (PDNS) due to PCV-2d-2 in naturally affected grower pigs of India

Porcine circovirus type 2 (PCV-2) is of great economic significance to porcine industry worldwide. PCV-2 variants and genotypes, alternating world over, are the etiological agent of several clinical syndromes such as porcine dermatitis and nephropathy syndrome (PDNS), post-weaning multi-systemic wasting syndrome (PMWS) and others in pigs. This study is reporting an atypical manifestation of PDNS in twelve grower pigs, 3- to - 4.5 months age and either sex, died of the disease, with predominant lesions of nephropathy and no obvious clinical lesions in skin. Necropsy examination of pigs showed lesions of petechial -to- ecchymotic hemorrhages in the kidneys and in the right auricular musculature of the hearts. Microscopic lesions in H & E sections of the kidneys showed acute glomerulonephritis, interstitial nephritis, and vasculitis, but the skin morphology and architecture remained unaltered in contrast to the pathognomonic lesions of PDNS described in the literature. Other syndromic associations of PDNS in these cases included-perimyocarditis, interstitial pneumonia, depleted lymphoid tissues, tonsillitis, enteritis, and meningo-encephalitis. The lesional sites in duplicate paraffin tissue sections of kidneys, heart, lungs, spleen, lymph nodes, intestine, and brain demonstrated PCV-2 antigen in the cytoplasm of cells as highlighted by the intense immunolabeling on IHC staining. The PCV-2 positive organs reconfirmed by PCR, targeting ORF2 gene, which yielded 481bp size of products. The sequencing results of 481bp products on phylogenetic analysis showed 94% similarity with that of PCV-2 sequences in the database that grouped into PCV2d-2 genotype. The present report confirms, probably for the first time, the atypical PDNS cases due to PCV2d-2 genotype in naturally affected grower pigs of India.

Green Synthesis, Characterization and Antimicrobial Activity of Copper Oxide Nanomaterial Derived from Momordica charantia

Background

In the emerging field of nanotechnology, copper oxide (CuO) nanomaterials are considered to be one of the most important transition metal oxides owing to its fascinating properties. Its synthesis from green chemistry principles is gaining importance as next-generation antibiotics due to its simplicity, eco-friendliness, and cost-effectiveness. In the present study, CuO nanorods (CuO NRs) were synthesized from the aqueous fruit extract of Momordica charantia and characterized using different analytical techniques. Further, the biomedical therapeutic potential was evaluated against multi-drug resistant microbial strains.

Materials and Methods

To synthesize CuO NRs, 0.1M of CuSO₄.5H₂O solution was added to aqueous extract of Momordica charantia in a 1:3 (v/v) ratio (pH=11) and heated at 50°C followed by washing and drying. The synthesized CuO NRs were subjected to characterization using different analytical techniques such as UV visible spectroscopy, zeta sizer equipped with zeta potential, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). Further, the application as a biomedical therapeutic potential was evaluated in vitro using well diffusion method against eleven multidrug-resistant clinical bacterial strains, a fungus- Trichophyton rubrum and in ovo against the R₂B virus using haemagglutination (HA) test.

Results

Characterization was preliminarily done by the spectral study that confirms the absorbance band at 245nm. FTIR analysis at 628 cm⁻¹ peak identified copper oxide vibration. SEM analysis revealed agglomerated particle clusters. However, with TEM clear nanorods of average diameter of 61.48 ± 2 nm were observed. EDAX confirmed CuO formation while XRD showed a typical monoclinic structure with 6 nm crystallite size. Biological screening of CuO NRs showed significant results against both in vitro and in ovo methods. Significant inhibitory activity (p<0.0001) was noted against most of the resistant human pathogenic strains including both Gram-positive and Gram-negative bacteria. The highest efficacy was observed against Bacillus cereus with a 31.66 mm zone of inhibition. Besides, the therapeutic potential of CuO NRs against Corynebacterium xerosis, Streptococcus viridians and R₂B strain of Newcastle disease is reported for the first time.

Conclusion

Based on the present results, it could be expected that green synthesized CuO NRs would find potential applications in the field of nanomedicine.

Comparing the efficiency of different Escherichia coli strains in producing recombinant capsid protein of porcine circovirus type 2

The present study was aimed at comparing different E. coli strains in expressing the capsid protein of Porcine Circovirus 2 (PCV2). Full length capsid protein could be expressed only in Rosetta-gami 2 (DE3) pLysS strain using pET32b (+) vector. This confirmed that only those strains which possess tRNAs for rare codons can express the full length capsid protein. Purification of full length capsid protein could not be achieved even after several attempts using native and denaturing conditions. Subsequently, an attempt was made for expression of N-terminal truncated capsid protein using the same expression system. Truncated capsid protein was successfully expressed, purified and characterized by western blotting. The truncated capsid protein was also shown to be efficacious in testing serum samples using an optimized indirect ELISA, wherein a diagnostic sensitivity of 88.89% and specificity of 90.82% was obtained as compared to commercially available GreenSpring® porcine circovirus (PCV2) ELISA test kit. Thus, the expressed truncated capsid protein appears to be a promising diagnostic agent for PCV2. The comparative analysis suggests that cluster of arginine residues at N-terminal of capsid protein not only affects its expression in some E. coli strains but also its purification by Ni-NTA chromatography, when expressed as a histidine tagged fusion protein.

Signature of genome wide gene expression in classical swine fever virus infected macrophages and PBMCs of indigenous vis-a-vis crossbred pigs

The genetic basis of differential host immune response vis-à-vis transcriptome profile was explored in PBMCs of indigenous (Ghurrah) and crossbred pigs after classical swine fever vaccination and in monocyte derived macrophages (MDMs) challenged with virulent classical swine fever (CSF) virus. The humoral immune response (E2 antibody) was higher (74.87%) in crossbred than indigenous pigs (58.20%) at 21st days post vaccination (21dpv). The rate of reduction of ratio of CD4⁺/CD8⁺ was higher in crossbred pigs than indigenous pigs at 7th days post vaccination (7dpv). The immune genes IFIT1, IFIT5, RELA, NFKB2, TNF and LAT2 were up regulated at 7dpv in RNA seq data set and was in concordance during qRT-PCR validation. The Laminin Subunit Beta 1 (LAMB1) was significantly (p ≤ 0.05) down-regulated in MDMs of indigenous pigs and consequently a significantly (p ≤ 0.01) higher copy number of virulent CSF virus was evidenced in macrophages of crossbred pigs than indigenous pigs. Activation of LXR:RXR pathway at 60 h post infection (60hpi) in MDMs of indigenous versus crossbred pigs inhibited nuclear translocation of NF-κB, resulted into transrepression of proinflammatory genes. But it helped in maintenance of HDL level by lowering down cholesterol/LDL level in MDMs of indigenous pigs. The key immune genes (TLR2, TLR4, IL10, IL8, CD86, CD54, CASP1) of TREM1 signaling pathway were upregulated at 7dpv in PBMCs but those genes were downregulated at 60hpi in MDMs indigenous pigs. Using qRT-PCR, the validation of differentially expressed, immunologically important genes (LAMB1, OAS1, TLR 4, TLR8 and CD86) in MDMs revealed that expression of these genes were in concordance with RNA-seq data.

Expression of Kisspeptin and its receptor in the hypothalamus of cyclic and acyclic buffalo (Bubalus bubalis)

Kisspeptin (Kiss1), neurokinin-B (NKB) and dynorphin (Dyn) neurons regulate the surge and pulsatile centres of gonadotropin releasing hormone (GnRH) in the hypothalamus and are modulated by the ovarian steroids. Accordingly, we studied the temporospatial expression of Kiss1, its receptor and other genes that regulate GnRH in the preoptic area (POA) and arcuate (ARC) regions of hypothalamus at different phases of bubaline estrous cycle. Brain of buffalo (n = 32) was collected immediately after exsanguination and categorized into early luteal (EL), mid luteal (ML), follicular (FL) stages and acyclic (n = 8/group). Total RNA was extracted from the POA and ARC of each stage and real time PCR amplification of Kiss1, Kiss1r, NKB, NKB receptor (NKBR), Dyn, Dyn receptor (OPRK1), GnRH1, ERα, PR, LEPR and GHSR was done using GAPDH as endogenous control and acyclic stage as calibrator group. Further, immunolocalization of Kiss1 and Kiss1r was done on the hypothalamus. In the POA, significant up-regulation of Kiss1 and NKB with a concomitant down-regulation of Dyn transcripts was recorded at FL stage. There was, however, down-regulation of Kiss1 and Kiss1r during the EL perhaps due to the loss of estradiol as a consequence of ovulation. On the other hand, in the ARC, there was a significant up-regulation of Kiss1 and Dyn at FL and ML, while NKB transcript was consistently down-regulated at any stage of estrous cycle. In the POA, expression of ERα was not modulated; however, PR was down-regulated in the EL. In the ARC, the ERα expression was significantly up-regulated in the EL, whereas, PR was moderately expressed irrespective of the stage of estrous cycle. The immunolocalization study revealed the presence of Kiss1 and Kiss1r in the POA and ARC in the cyclic buffalo with relative abundance at FL. The transcriptional profile of the genes suggests that there is estrous cycle stage specific expression of Kiss1, Kiss1r and other GnRH regulating genes in the POA and ARC regions of hypothalamus in the buffalo. Up-regulation of Kiss1r in the POA during ML and ARC during EL indicates the involvement of kisspeptinergic system in the regulation of low LH pulse frequencies during the early and mid luteal phases in the cyclic buffalo.

Genome-wide integrated analysis of miRNA and mRNA expression profiles to identify differentially expressed miR-22-5p and miR-27b-5p in response to classical swine fever vaccine virus

The present study was conducted to identify the differentially expressed miRNAs (DE miRNAs) in the peripheral blood mononuclear cells of crossbred pigs in response to CSF vaccination on 7 and 21 days of post vaccination as compared to unvaccinated control (0 dpv). Simultaneously, set of miRNA was predicted using mRNA seq data at same time point. The proportion of CD4^-CD8⁺ and CD4⁺CD8⁺ increased after vaccination, and the mean percentage inhibition was 86.89% at 21 dpv. It was observed that 22 miRNAs were commonly expressed on both the time points. Out of predicted DE miRNAs, it was found that 40 and 35 DE miRNAs were common, obtained from miRNA seq analysis and predicted using mRNA seq data on 7 dpv versus 0 dpv and 21 dpv versus 0 dpv respectively. Two DE miRNAs, ssc-miR-22-5p and ssc-miR-27b-5p, were selected based on their log₂ fold change and functions of their target genes in immune process/pathway of viral infections. The validations of DE miRNAs using qRT-PCR were in concordance with miRNA seq analysis. Two set of target genes, CD40 and SWAP70 (target gene of ssc-miR-22-5p) and TLR4 and Lyn (target gene of ssc-miR-27b-5p), were validated and were in concordance with results of RNA seq analysis at a particular time point (except TLR4). The first report of genome-wide identification of differentially expressed miRNA in response to live attenuated vaccine virus of classical swine fever revealed miR-22-5p and miR-27b-5p were differentially expressed at 7 dpv and 21 dpv.

Serological profiling of rabies antibodies by enzyme-linked immunosorbent assay and its comparative analysis with rapid fluorescent focus inhibition test in mouse model

Aim:

In this study, we have used enzyme-linked immunosorbent assay (ELISA) as an alternative test to replace the cumbersome rapid fluorescent focus inhibition test (RFFIT) to ascertain the immune status of immunized mice against rabies virus.

Materials and Methods:

Rabies is a devastating disease worldwide caused by rabies virus. Proper usage of pre- or post-exposure rabies vaccine can prevent the disease transmission. In this study, mice were immunized with Vero cell-adapted inactivated rabies vaccine. RFFIT was used as a test to determine the serum neutralizing titers in infected/vaccinated mice. Seroprofiling of mice sera was done in vitro by ELISA.

Results:

Twenty-one days post-immunization, both ELISA and RFFIT assays indicated similar antibody levels in mice sera that were immunized with Vero cell-adapted inactivated rabies vaccine. Both the tests were correlated, and the linearity was verified by the regression line (R²=0.979).

Conclusion:

In this study, we profiled the serological status of Vero cell-adapted inactivated rabies vaccine through ELISA in mice model that correlated well with the OIE gold standard test RFFIT.

Endometrial transcripts of proinflammatory cytokine and enzymes in prostaglandin synthesis are upregulated in the bitches with atrophic pyometra

Inflammatory markers of endometrial origin are valuable in order to differentiate the pyometra from cystic endometrial hyperplasia in the bitch. In the present study, we hypothesized that histological categorization would distinguish the differential regulation of the proinflammatory genes in the endometrium of bitches with pyometra. Ovariohysterectomy was done on bitches with confirmatory diagnosis of pyometra (n = 18). Using endometrium to myometrium ratio of 0.79 as threshold, the uteri (n = 8/group) were categorized into hyperplastic pyometra (HP) and atrophic pyometra (AP). Two samples were excluded as the diagnosis was inconclusive. In parallel, endometrial tissue was collected for total RNA extraction to study the differential expression of TLR4, IL-6, IL-8, COX-2 and PGFS through real time PCR. Diestrus uterus of non-pyometra bitches (n = 6) served as control. The mean fold change (2^-ΔΔCt) for the target genes was determined using β-actin as endogenous control and non-pyometra uterus as calibrator group. Except TLR4, other inflammatory genes were upregulated significantly by 1.82 to 3.74 times in the AP as compared to HP with maximum upregulation of COX-2 and PGFS. Further, correlation matrix with Spearman's rho revealed that IL-8 had strong positive correlation with COX-2 and PGFS in the AP group (P < 0.05). It is concluded that histological grading of pyometra into HP and AP revealed differential regulation of inflammatory cytokines and enzymes in the PG synthetic pathway in the canine endometrium that has diagnostic potential under clinical settings.

Determination of immune status in dogs against CPV-2 by recombinant protein based latex agglutination test

Canine parvoviral enteritis is a highly contagious viral illness caused by canine parvovirus-2 (CPV-2) which affects puppies of mainly 6-20 weeks of age. Vaccination is pivotal in preventing and controlling CPV-2 infection. Determination of antibody status is a critical determinant for successful vaccination. The hemagglutination inhibition (HI) test is 'gold standard' test for quantification of antibodies specific to CPV-2, although the execution of this test is not feasible under field conditions. The present study was undertaken to develop a point of care testing to determine immune status prior to CPV-2 vaccination or to detect seroconversion in immunized dogs by latex agglutination test (LAT) using recombinant antigen. Truncated portion of VP2 protein (tVP2) of CPV-2 was selected on the basis of antigenic indices, overexpressed the recombinant protein in E. coli system and was subsequently used in development of LAT. A total of 59 serum samples obtained from vaccinated (n = 54) and healthy unvaccinated (n = 5) dogs were tested. The positivity was observed in 85% (46/54) of these dogs with varying agglutination pattern. The overall sensitivity and specificity of latex agglutination test in comparison to HI test was recorded as 90% and 88% respectively with an agreement value of 90% (CI = 95%).

Biological and molecular characterization of classical swine fever challenge virus from India

Aim:

The aim of this study was biological and molecular characterization of classical swine fever (CSF) challenge virus from India.

Materials and Methods:

CSF challenge virus maintained at Division of Biological standardization was experimentally infected to two seronegative piglets. The biological characterization was done by clinical sign and symptoms along with postmortem findings. For molecular characterization 5’-nontranslated region, E2 and NS5B regions were amplified by reverse transcription polymerase chain reaction and sequenced. The sequences were compared with that of reference strains and the local field isolates to establish a phylogenetic relation.

Results:

The virus produced symptoms of acute disease in the piglets with typical post-mortem lesions. Phylogenetic analysis of the three regions showed that the current Indian CSF Challenge virus is having maximum similarity with the BresciaX strain (USA) and Madhya Pradesh isolate (India) and is belonging to subgroup 1.2 under Group 1.

Conclusion:

Based on biological and molecular characterization of CSF challenge virus from India is described as a highly virulent virus belonging to subgroup 1.2 under Group 1 along with some field isolates from India and Brescia strain.