K.G. Tirumurugaan

Differential expression of toll-like receptor mRNA in selected tissues of goat (Capra hircus)

Pattern recognition receptors (PRRs) expressed by various immune cells and tissues have been shown to play a pivotal role in the recognition of pathogens by the host. The present study was carried out to identify toll-like receptors (TLRs) 1-10 mRNA in goat peripheral blood mononuclear cells (PBMCs) and selected tissues including jejunum, lung, lymph node, skin, spleen and uterus using reverse transcriptase polymerase chain reaction (RT-PCR). Our results confirm earlier reports regarding the evolutionarily conserved nature of these receptors as successful amplification of the goat TLR mRNAs could be obtained with bovine TLR mRNA-specific primers. The partial sequences of the purified TLR PCR amplicons had 93.8-99.7% nucleotide identity with sheep TLR cDNA sequences available in the GenBank. Semi-quantification of the expression levels of the TLR mRNAs was done using densitometric analysis of band intensities. All the TLR mRNAs (1-10) were expressed in high amounts in the lymph node while spleen showed lower expression of TLR 6 and 10 mRNAs. PBMC and lung expressed all TLR mRNAs in high amounts except TLR 10 mRNA. In uterus and jejunum, lower expression of TLR 3, 4 and 10 mRNAs was seen. Skin had the lowest repertoire of TLR mRNA expression with lower or no expression of TLR 2, 3, 4, 8, 9 and 10 mRNAs. Another interesting observation was that tissues such as uterus, lung and skin that exhibited lower levels of TLR 2 had higher levels of TLR 6 mRNAs.

Genotypic and pathotypic characterization of Newcastle disease viruses from India.

Newcastle disease virus (NDV) is an avian paramyxovirus that causes significant economic losses to the poultry industry in most parts of the world. The susceptibility of a wide variety of avian species coupled with synanthropic bird reservoirs has contributed to the vast genomic diversity of this virus as well as diagnostic failures. Since the first panzootic in 1926, Newcastle disease (ND) became enzootic in India with recurrent outbreaks in multiple avian species. The genetic characteristics of circulating strains in India, however, are largely unknown. To understand the nature of NDV genotypes in India, we characterized two representative strains isolated 13 years apart from a chicken and a pigeon by complete genome sequence analysis and pathotyping. The viruses were characterized as velogenic by pathogenicity indices devised to distinguish these strains. The genome length was 15,186 nucleotides (nt) and consisted of six non-overlapping genes, with conserved and complementary 3′ leader and 5′ trailer regions, conserved gene starts, gene stops, and intergenic sequences similar to those in avian paramyxovirus 1 (APMV-1) strains. Matrix gene sequence analysis grouped the pigeon isolate with APMV-1 strains. Phylogeny based on the fusion (F), and hemagglutinin (HN) genes and complete genome sequence grouped these viruses into genotype IV. Genotype IV strains are considered to have “died out” after the first panzootic (1926–1960) of ND. But, our results suggest that there is persistence of genotype IV strains in India.

Regulation of CD38 expression in human airway smooth muscle cells: role of class I phosphatidylinositol 3 kinases.

The ADP-ribosyl cyclase activity of CD38 generates cyclic ADP-ribose, a Ca(2+)-mobilizing agent. In human airway smooth muscle (HASM) cells, TNF-α mediates CD38 expression through mitogen-activated protein kinases and NF-κB and AP-1. The phosphatidylinositol-3 kinase/Akt (PI3K/Akt) pathway is involved in TNF-α signaling and contributes to airway hyperresponsiveness and airway remodeling. We hypothesized that PI3Ks mediate CD38 expression and are involved in the differential induction of CD38 by TNF-α in asthmatic HASM cells. HASM cells were treated with pan-PI3K inhibitors (LY294002 or wortmannin) or class I-selective (GDC0941) or isoform-selective PI3K inhibitors (p110α-PIK-75 and p110β-TGX-221) with or without TNF-α. HASM cells were transfected with a catalytically active form of PI3K or phosphatase and tensin homolog (PTEN) or nontargeting or p110 isoform-targeting siRNAs before TNF-α exposure. CD38 expression and activation of Akt, NF-κB, and AP-1 were determined. LY294002 and wortmannin inhibited TNF-α-induced Akt activation, whereas only LY294002 inhibited CD38 expression. P110 expression caused Akt activation and basal and TNF-α-induced CD38 expression, whereas PTEN expression attenuated Akt activation and CD38 expression. Expression levels of p110 isoforms α, β, and δ were comparable in nonasthmatic and asthmatic HASM cells. Silencing of p110α or -δ, but not p110β, resulted in comparable attenuation of TNF-α-induced CD38 expression in asthmatic and nonasthmatic cells. NF-κB and AP-1 activation were unaltered by the PI3K inhibitors. In HASM cells, regulation of CD38 expression occurs by specific class I PI3K isoforms, independent of NF-κB or AP-1 activation, and PI3K signaling may not be involved in the differential elevation of CD38 in asthmatic HASM cells.

Toll-Like Receptor Responses to Peste des petits ruminants Virus in Goats and Water Buffalo

Ovine rinderpest or goat plague is an economically important and contagious viral disease of sheep and goats, caused by the Peste des petits ruminants virus (PPRV). Differences in susceptibility to goat plague among different breeds and water buffalo exist. The host innate immune system discriminates between pathogen associated molecular patterns and self antigens through surveillance receptors known as Toll like receptors (TLR). We investigated the role of TLR and cytokines in differential susceptibility of goat breeds and water buffalo to PPRV. We examined the replication of PPRV in peripheral blood mononuclear cells (PBMC) of Indian domestic goats and water buffalo and demonstrated that the levels of TLR3 and TLR7 and downstream signalling molecules correlation with susceptibility vs resistance. Naturally susceptible goat breeds, Barbari and Tellichery, had dampened innate immune responses to PPRV and increased viral loads with lower basal expression levels of TLR 3/7. Upon stimulation of PBMC with synthetic TLR3 and TLR7 agonists or PPRV, the levels of proinflammatory cytokines were found to be significantly higher while immunosuppressive interleukin (IL) 10 levels were lower in PPRV resistant Kanni and Salem Black breeds and water buffalo at transcriptional level, correlating with reduced viralloads in infected PBMC. Water buffalo produced higher levels of interferon (IFN) α in comparison with goats at transcriptional and translational levels. Pre-treatment of Vero cells with human IFNα resulted in reduction of PPRV replication, confirming the role of IFNα in limiting PPRV replication. Treatment with IRS66, a TLR7 antagonist, resulted in the reduction of IFNα levels, with increased PPRV replication confirming the role of TLR7. Single nucleotide polymorphism analysis of TLR7 of these goat breeds did not show any marked nucleotide differences that might account for susceptibility vs resistance to PPRV. Analyzing other host genetic factors might provide further insights on susceptibility to PPRV and genetic polymorphisms in the host.

Expression profile of toll-like receptor 2 mRNA in selected tissues of shark (Chiloscyllium sp.)

Sharks are a species of delight for immunologists from the evolutionary perspective since it is considered as the first species to have evolved the adaptive immune responses in addition to the innate immune system. One of the components of the highly conserved innate immune system is the toll-like receptors (TLR) which has a conserved overall protein structure throughout deuterostome evolution. There is no report that demonstrates the expression of these receptors in sharks. In this study we successfully amplified a 270 bp amplicon using a degenerate primer design strategy that corresponded to the Toll/IL-1 receptor (TIR) domain of TLR2 (GenBank ID: JF792813). BLAST analysis revealed a maximum nucleotide identity of 87% and 76% with the TLR2 of higher mammals and teleost fishes respectively. Domain prediction revealed a TIR structure between 1 and 87 amino acids that had a maximum identity of 58% and 76% with TLR2 - TIR protein of teleost fishes and higher mammals respectively. Phylogenetic analysis revealed a closer clustering of the shark TIR sequence with those from human, cattle, goat, sheep and chicken than with other fish species. Basal expression levels of the TLR2-TIR mRNA were found to be significantly higher in kidneys followed by fins, spleen and intestinal spiral valve (ISV). In tissues such as spleen and kidney the expression of the TLR2-TIR mRNA could be localized to lymphoid and macrophages like cells and tubular epithelial cells respectively. In-vivo exposure of sharks to peptidoglycan (TLR 2 ligand) resulted in 9 folds higher expression of TLR2-TIR mRNA in gills followed by 5 folds in the fins. However, when inoculated with a TLR ligand pool, the expression levels significantly increased to 12 fold in skin followed by epigonal, kidneys and ISV. These findings not only support the presence of the TLRs in sharks but also their induction upon exposure to specific ligands. Further studies are needed to identify their numbers, their ligand specificity and downstream cytokine responses.

Analysis of the Fusion Protein Cleavage Site of Newcastle disease virus Isolates from India Reveals Preliminary Evidence for the Existence of II, VI and VII Genotypes

Newcastle disease virus (NDV) has been a threat to poultry industry in most of the developing countries with a wide variety of avian species being susceptible, coupled with the presence of mobile wild bird reservoirs contributing not only to the vast genomic diversity of this virus but also to the diagnostic failures. NDV of multiple genotypes (I–XI) is known to be prevalent and reported worldwide. However, there is a paucity of information on the circulating genotypes of NDV in India. This study utilized the fusion protein cleavage site (FPCS) sequence to determine the different genotypes of NDV circulating in India. Our results indicate that majority of NDV isolates from southern states of India namely, Tamil Nadu, Kerala and Karnataka were found to belong to genotype II. However, some of the strains from Tamil Nadu and most from Uttar Pradesh belong to genotype groups VI and VII. Interestingly, three isolates recovered from Tamil Nadu grouped with genotype IV viruses (namely Herts/33) which had not been hitherto reported to GenBank since 1989. This preliminary information points to the existence of multiple genotypes and also the need for efficacy studies with vaccines incorporating multiple genotypes in controlling virulent NDV (vNDV) outbreaks in India.

Comparative analysis of innate immune response following in vitro stimulation of sheep and goat peripheral blood mononuclear cells with bluetongue virus - serotype 23.

Bluetongue is an infectious disease caused by bluetongue virus (BTV), which affects sheep, goat, cattle and certain wild ruminants. However severe clinical signs are usually seen with significant mortality in sheep than cattle and goat. To date, comparative studies on innate immune responses of sheep and goat infected with BTV is lacking. In this study, we compared the innate immune response of sheep and goat by infecting the peripheral blood mononuclear cells (PBMCs) with BTV serotype 23. In our study, we observed that sheep PBMCs supports higher virus replication than goat PBMCs. To delineate the role of innate immune response in differential viral replication observed in this study, we examined TLR3 (Receptor for dsRNA virus) mRNA expression and cytokine profiles (IL-1β, Il-6, IL-8, Il-10, IL-12p40, TNF-α, IFN-γ and IFN-α) following Poly I:C (TLR3 ligand) stimulation and BTV 23 infection. In our present study, sheep PBMCs had significantly higher TLR3 mRNA levels, TLR3 specific ligand (Poly I:C) stimulation resulted in increased levels of IFN-γ at transcriptional and translational levels along with IL-8 and IL-10 at transcriptional levels. Whereas, the levels of TNF-α was higher in goat PBMCs at transcriptional levels. BTV infected sheep PBMCs expressed significantly higher levels of IFN-γ at transcriptional and translational levels along with IL-6, IL-8 and IL-10 at transcriptional levels. Whereas the expression levels of TNF-α and IFN-α at transcriptional and translational levels were significantly high in goat PBMCs. To examine the potential factor for consistent increase in the expression of TNF-α, we sequenced the promoter region of TNF-α and identified a total of five single nucleotide polymorphisms (SNP) and one indel in goat TNF-α promoter region. Luciferase assay for transcriptional activity of the promoter showed that goat TNF-α has significantly enhanced transcriptional activity in comparison with sheep TNF-α promoter. Altogether, our data suggests that the expression levels of TNF-α and IFN-α and/or IL-10 plays crucial role in replication of BTV 23.

Complete Genome Sequence of a Newcastle Disease Virus from a Coturnix coturnix japonica (Japanese Quail) Covey in India.

ABSTRACT The genome of a Newcastle disease virus isolated from a Japanese quail in 2003 is reported here. The genome is 15,192 nucleotides (nt) long, as found in the recent genotypes, and grouped as genotype VIIb, with a 6-nt insertion. This is the first report on the sequence of a genotype VII Newcastle disease virus (NDV) from India.

Transcript profiling of pattern recognition receptors in a semi domesticated breed of buffalo, Toda, of India

The primary objective of this study was to assess the expression profile and levels of toll-like receptor (TLR) mRNAs in the spleen, lung, mediastinal lymph node (MLN), jejunum, rectum, skin and peripheral blood mononuclear cells (PBMC) of Toda and Murrah buffalos. Spleen and PBMC had increased expression of TLR mRNAs 2, 4, 5, 6, 8, 9 and 10; lung had increased expression of TLR mRNAs 2, 4, 5, 6 and 8, MLN TLR mRNA 6, 9, 10 and decrease in TLR 3 and 7 mRNAs in skin. No significant differences were observed in the expression levels of any of the TLR mRNA in jejunum and rectum. Toda buffaloes showed significantly higher expression levels of TLR 9 mRNA in MLN, TLR mRNAs 1, 5, 6, 9 and 10 in skin and TLR mRNAs 2, 4, 7 and 9 in PBMC than Murrah buffaloes living in the vicinity. Toda and Murrah buffaloes were inoculated with TLR5 (flagellin) and TLR9 (CpG ODN) ligands in vivo and expression levels of the respective TLRs analyzed 12h later. Following CpG inoculation, Toda buffaloes had significantly higher levels of TLR 9 mRNA expression but not in Murrah. However, flagellin induction did not increase TLR 5 mRNA expression in both these breeds. Histological sections of the skin were made and infiltrating cell clusters were graded and quantified. Following CpG inoculation, Toda buffaloes showed higher numbers of infiltrating grade 1 and grade 3 cell clusters while Murrah showed lower numbers of infiltrating grade 1 cells as compared to mock-inoculated skin sections. Flagellin treatment revealed no significant differences in infiltrating cell clusters in both the breeds. The results have shown differential expression of TLR mRNAs in various tissues between two divergent buffalo breeds with the highest difference in TLR expression profile seen in the skin, the largest portal of entry of pathogens, of Toda.

Comparative in vitro toll-like receptor ligand induced cytokine profiles of Toda and Murrah buffaloes—Identification of tumour necrosis factor alpha promoter polymorphism

The objective of this study was to assess cytokine production upon activation of pattern recognition receptors responsible for sensing bacterial and viral pathogen associated molecular patterns in two genetically diverse buffalo breeds, Toda and Murrah. A very limited molecular-epidemiological analysis showed a higher prevalence of Anaplasma and Theileria in Murrah than Toda buffaloes. Toda buffalo peripheral blood mononuclear cells (PBMC) produced significantly higher levels of IFN γ and/or TNF α mRNAs in response to peptidoglycan, poly I:C, lipopolysaccharide, imiquimod and CpG. Flagellin stimulation did not result in any significant differences in the expression levels of the cytokines tested between these breeds. The levels of ligand induced IFN γ and TNF α mRNA and proteins also correlated except when induced with CpG. The proximal promoter region of TNF α across these two breeds were also sequenced to detect SNPs and promoter assay performed to determine their role in altering the transcriptional activity. Two polymorphisms were identified at -737 (T/A) and -1092 (G/T) positions in Toda buffalo TNF α promoter and promoter assay revealed higher transcription activity in Toda buffalos than in Murrah. This suggests that disease tolerance of these buffalo breeds could be due to the differences in their cytokine transcription levels in response to the respective PAMPs that may be at least in part determined by polymorphisms in the cytokine promoter regions.