Purification and Characterization of the Lecithin-Dependent Thermolabile Hemolysin Vhe1 from the Vibrio sp. Strain MA3 Associated with Mass Mortality of Pearl Oyster (Pinctada fucata).

In a previous study, we isolated a Vibrio sp. strain MA3 and its virulence factor, a hemolysin encoded by vhe1. This strain is associated with mass mortalities of the pearl oyster Pinctada fucata. In the present study, the vhe1 gene from strain MA3 was cloned and its encoded product was purified and characterized. Our results show that the vhe1 gene encodes a protein of 417 amino acids with an estimated molecular mass of 47.2 kDa and a pI of 5.14. The deduced protein, Vhe1, was found to contain the conserved amino acid sequence (GDSL motif) of the hydrolase/esterase superfamily and five conserved blocks characteristic of SGNH hydrolases. A BLAST homology search indicated that Vhe1 belongs the lecithin-dependent hemolysin/thermolabile hemolysin (LDH/TLH) family. In activity analyses, the optimal temperature for both the hemolytic and phospholipase activities of Vhe1 was 50 °C. Vhe1 hemolytic activity and phospholipase activity were highest at pH 8.5 and pH 8.0, respectively. However, both enzymatic activities sharply decreased at high temperature (> 50 °C) and pH < 7.0. Compared with previously reported hemolysins, Vhe1 appeared to be more thermal- and pH-labile. Both its hemolytic activity and phospholipase activity were significantly inhibited by CuCl2, CdCl2, ZnCl2, and NiCl2, and slightly inhibited by MnCl2 and CoCl2. Vhe1 showed higher phospholipase activity toward medium-chain fatty acids (C8-C12) than toward shorter- and longer-chain fatty acids. These results accumulate knowledge about the LDH/TLH of V. alginolyticus, which detailed characterization has not been reported, and contribute to solving of the mass mortality of pearl oyster.

Nacre extract from pearl oyster attenuates amyloid beta-induced memory impairment.

Shells are composed of two types of calcium carbonate polymorphs-the prismatic layer and the nacreous layer. Pearls, composed of the nacreous layer, have been used in Chinese medicine since ancient times. We have previously shown that extracts from the nacreous layer improves scopolamine-induced memory impairment. However, whether pearl ameliorates cognitive disorders induced by amyloid-ß 1-40 (Aß1-40) has not been elucidated. In this study, we investigated whether nacre extract improves memory impairment induced by intracerebroventricular injection of Aß1-40. Administration of nacre extract led to recovery from Aß1-40-induced impairments in object recognition, short-term memory, and spatial memory. Nacre extract reversed the increase in lipid peroxidation caused by Aß1-40 in the cerebral cortex by increasing the expression of catalase and superoxide dismutase. In addition, nacre extract recovered the expression and phosphorylation of cyclic AMP response element-binding protein (CREB), which decreased with Aß1-40 treatment, and increased the expression of brain-derived neurotrophic factor and neuropeptide Y, which are regulated by CREB. Nacre extract also suppressed acetylcholine esterase activity and Aß1-40-induced tau phosphorylation. Histochemical analysis of the hippocampus region showed that the nacre extract protected against Aß1-40-induced neuronal loss in the hippocampus. These results suggest that nacre extract protects against Aß1-40-induced neuronal cell death by suppressing oxidative stress and increasing the expression and phosphorylation of CREB.

Protective Effect of the Pearl Extract from Pinctada fucata martensii Dunker on UV-Induced Photoaging in Mice.

Although the effect of pearl powder has been recognized for more than a thousand years from healthcare to beauty care, there has yet to be an in-depth understanding of its anti-photoaging effect. In the present study, the protective effect of pearl extract (PE) on UV-induced photoaging in mice was evaluated. First, the amino acid analysis of PE was carried out. Then, different dosages of pearl extract gel (PEG) were applied topically on the shaved dorsal skins regions of mice before UV irradiation. Skin physiological and histological analysis, antioxidant enzymes and inflammatory factor test were used to evaluate the anti-photoaging effect of PEG. The results showed that PEG contained 14 amino acids, and could inhibit UV-irritated skin wrinkles, laxity, thickness, and dryness. Moreover, PEG upregulated the activities of CAT, GSH-Px, SOD and decreased MDA level, and suppressed the production of IL-1ß, IL-6, PGE2 , TNF-α, and COX-2 in UV-irradiated mice. The therapeutic effect in high dose PEG group was superior to those of positive control (Vitamin E). This study demonstrated the underlying mechanisms of PEG against UV-irritated photoaging. And PEG possesses a potential use in photoprotective medicines and cosmetics.

PU14, a Novel Matrix Protein, Participates in Pearl Oyster, Pinctada Fucata, Shell Formation.

Biomineralization is a widespread biological process, involved in the formation of shells, teeth, and bones. Shell matrix proteins have been widely studied for their importance during shell formation. In 2015, our group identified 72 unique shell matrix proteins in Pinctada fucata, among which PU14 is a matrix protein detected in the soluble fraction that solely exists in the prismatic layer. However, the function of PU14 is still unclear. In this study, the full-length cDNA sequence of PU14 was obtained and functional analyses of PU14 protein during shell formation were performed. The deduced protein has a molecular mass of 77.8 kDa and an isoelectric point of 11.34. The primary protein structure contains Gln-rich and random repeat units, which are typical characteristics of matrix protein and indicate its potential function during shell formation. In vivo and in vitro experiments indicated PU14 has prismatic layer functions during shell formation. The tissue expression patterns showed that PU14 was mainly expressed in the mantle tissue, which is consistent with prismatic layer formation. Notching experiments suggested that PU14 responded to repair and regenerate the injured shell. After inhibiting gene expression by injecting PU14-specific double-stranded RNA, the inner surface of the prismatic layer changed significantly and became rougher. Further, in vitro experiments showed that recombinant protein rPU14 impacted calcite crystal morphology. Taken together, characterization and functional analyses of a novel matrix protein, PU14, provide new insights about basic matrix proteins and their functions during shell formation.

Control of biofouling on pearl oysters Pinctada imbricata using wax and Chinese herbs.

Biofouling poses severe challenges to pearl oyster Pinctada imbricata culture in China, and controlling it is both labor- and capital-intensive. The antifouling properties of wax, and wax mixed with Chinese herbs, sprayed onto pearl oyster shell surfaces during peak biofouling seasons were evaluated. Pearl oysters coated with three wax treatments (plain wax, Chinaberry seed extract, Chinese honeylocust fruit extract) and a control (no treatment), were cultured in nets for up to 60 days. Mortality rate, fouling organism and pearl-oyster weights, and shell height are reported for individual oysters on each of six sampling dates. With the exception of oysters submerged for 12 days, all oysters were significantly affected by treatment type and submersion duration. Fouling weight increased more rapidly over time in the control-treatment oysters. Wax-based coatings deterred fouling-organism settlement on oysters for at least 2 months during the intensive fouling season, reducing mortality and not adversely effecting growth.

Purification and functional analysis of the shell matrix protein N66 from the shell of the pearl oyster Pteria sterna.

Mollusk biomineralization is a process controlled by a complex interplay of proteins, ions and external regulators. In spite of several studies, there is a lack of knowledge of who (molecules involved), how (mechanism) and why (evolution and adaptation) mollusk are designed as we know them. In this study, a shell matrix protein, N66, has been purified and characterized biochemically from the shell of Pteria sterna. Two protein bands with carbohydrates associated were separated with a molecular weight of ~60 and 64 kDa. It has carbonic anhydrase activity and it is able to form crystal polymorphs of calcium carbonate in vitro. The mRNA N66 was obtained from the mantle tissue of Pteria sterna and the deduced amino acid sequence contained a carbonic anhydrase (CA) domain and a Asn/Gly-rich domain (aa243-439). The CA domain contained three His residues acting as zinc ligands and the gate-keeper residues present in all α-CAs (Glu166-Thr525), being thus similar to the human isoform hCAVII. Also, to test whether the posttranslational modifications present on the native N66 affects the CA activity and its crystallization capability in vitro, a recombinant N66 was overexpressed in Escherichia coli and functionally characterized. Our results show that recombinant N66 has higher CA activity and produce larger size crystals in vitro than the native N66 protein, suggesting that intrinsic properties of the native N66, such as glycosylations and/or phosphorylations, might regulate its activity.

Nanoscaled pearl powder accelerates wound repair and regeneration in vitro and in vivo.

Pearl powder has been used to treat many diseases like palpitations, insomnia, and epilepsy for thousands of years in Chinese medicine. It has demonstrated antioxidant, antiaging, antiradiative, and tonic activities. Pearl powder contains multiple active proteins, which are nutritious for skin cells and might be advantageous for wound repair and regeneration. However, its healing effect in vivo was not reported yet. This study aims to investigate the effects and the underlying mechanism of the pearl powders with different particle sizes in wound treatment. Briefly, the pearl powder with different sizes was characterized for their particle sizes and morphology. The protein release profiles of these powders were also studied. The influence of the different size of pearl powder in the proliferation, migration of skin cells was evaluated. Then, with the rat skin excision model, the effect of pearl powder on wound repair and regeneration was investigated. It was demonstrated that, all the micro and nanosized pearl powders could both increase the proliferation and migration of skin cells and accelerate the wound closure, as well as significantly enhanced the biomechanic strength of the healed skins. Moreover, the pearl powder treatment could improve the formation and regular deposition of collagen, and enhance the skin angiogenesis. Among all these in vitro and in vivo investigations, nanoscale pearl powder expressed the highest efficiency for healing. The mechanism might be contributed to the increased release of active proteins, enhanced tissue attachment, and the increased cellular uptake for the nano powder at the topical site.

Nacre formation by epithelial cell cultures from mantle of the black-lip pearl oyster, Pinctada margaritifera.

Mantle tissue from the black-lip pearl oyster, Pinctada margaritifera, was cultured in vitro using sterilized seawater supplemented with 0.1% yeast extract as the culture medium. Granular and agranular epithelial cells, hyalinocytes, and fibroblast-like cells were observed in the initial stages of culture. Epithelial cells later formed pseudopodial cell networks containing clusters of granulated cells, which upon maturation released their colored granules. These granules induced formation of nacre crystal deposits on the bottom of the culture plate. Cultures comprised of only granulated epithelial cells were established through periodic sub-culturing of mantle cells and maintained for over 18 mo in a viable condition. Reverse transcriptase PCR of cultured cells demonstrated gene expression of the shell matrix protein, nacrein. To further evaluate the functional ability of cultured granulated epithelial cells, nuclear shell beads were incubated in culture medium containing these cells to induce nacre formation on the beads. Observation of the bead surface under a stereomicroscope at periodic intervals showed the gradual formation of blackish yellow colored nacre deposits. Examination of the bead surface by scanning electron microscopy and energy dispersive X-ray analysis at periodic intervals revealed a distinct brick and mortar formation characteristic of nacre, comprised of aragonite platelets and matrix proteins. Calcium, carbon, and oxygen were the major elements in all stages examined. Our study shows that mantle epithelial cells in culture retain the ability to secrete nacre and can therefore form the basis for future studies on the biomineralization process and its application in development of sustainable pearl culture.

fam20C participates in the shell formation in the pearl oyster, Pinctada fucata.

Kinase-family with sequence similarity 20, member C (Fam20C) is a protein kinase, which can phosphorylate biomineralization related proteins in vertebrate animals. However, the function of Fam20C in invertebrate animals especially the role in biomineralization is still unknown. Herein, we cloned the cDNA of fam20C from the pearl oyster, Pinctada fucata. It is showed that the expression of fam20C in the mantle edge was much higher than other tissues. In situ hybridization showed that fam20C was expressed mostly in the outer epithelial cells of the middle fold, indicating it may play important roles in the shell formation. Besides, fam20C expression increased greatly in the D-shape stage of pearl oyster development, when the shell was first formed. During the shell repair process, the expression level of fam20C increased 1.5 times at 6 h after shell notching. Knockdown of fam20C in vivo by RNA interference resulted in abnormally stacking of calcium carbonate crystals at the edges of nacre tablets, showing direct evidence that fam20C participates in the shell formation. This study provides an insight into the role of kinase protein in the shell formation in mollusk and broaden our understanding of biomineralization mechanism.

Efficacy of protein rich pearl powder on antioxidant status in a randomized placebo-controlled trial.

Pearl is one of the well-known traditional Chinese medicine (TCM) prescribed for treating various skin and bone related disorders due to its abundant proteins and mineral contents. The present investigation focused on antioxidation and life span prolonging effects from different extracts of pearl powder. During in vitro studies, various oxidative indices were evaluated, along with lifespan-prolonging effect were checked using wild-type Caenorhabditis elegans. For the clinical trial, 20 healthy middle-aged subjects were recruited and separated into 2 groups as experimental and placebo group, who received 3 g of pearl powder/d (n = 10) and 3 g of placebo/d (n = 10) for 8 weeks, respectively. During the initial, 2nd, 4th, 6th, 8th and 10th weeks the blood samples were collected for biochemical analysis. The protein extract of pearl powder recorded maximum (p < 0.05) antioxidant activity (20-68%) as well as efficiently prolonged the life span of C. elegans by 18.87%. Pearl powder supplemented subjects showed a substantial increase (p < 0.05) in total antioxidant capacity from 0.45 to 0.69 mM, total thiols from 0.23 to 0.29 mM, Glutathione content from 5.89 to 9.19 µM, enzymic antioxidant activity (SOD-1248 to 1308; Gpx-30 to 32; GR-2.4 to 2.9) as well as considerably suppressed the lipid peroxidation products from 4.95 to 3.27 µM. The outcome of both in-vitro and in-vivo antioxidant activity inferred that protein extract of pearl powder was a potent antioxidant and thereby prolonged the lifespan of C. elegans. Hence, pearl powder could be recommended for treating various age-related degenerative disorders.

[Pharmacological mechanism analysis of oligopeptide from Pinctada fucata based on in silico proteolysis and protein interaction network].

Pinctada fucata oligopeptide is one of key pharmaceutical effective constituents of P. fucata. It is significant to analyze its pharmacological effect and mechanism. This study aims to discover the potential oligopeptides from P. fucata and analyze the mechanism of P. fucata oligopeptide based on in silico technologies and protein interaction network(PIN). First, main protein sequences of P. fucata were collected, and oligopeptides were obtained using in silico gastrointestinal tract proteolysis. Then, key potential targets of P. fucata oligopeptides were obtained through pharmacophore screening. The protein-protein interaction(PPI) of targets was achieved and implemented to construct PIN and analyze the mechanism of P. fucata oligopeptides. P. fucata oligopeptide database was constructed based on in silico technologies, including 458 oligopeptides. Twelve modules were identified from PIN by a graph theoretic clustering algorithm Molecular Complex Detection(MCODE) and analyzed by Gene ontology(GO) enrichment. The results indicated that P. fucata oligopeptides have an effect in treating neurological diseases, such as Alzheimer's disease. In silico proteolysis could be used to analyze the protein sequences of traditional Chinese medicine(TCM). According to the combination of in silico proteolysis and PIN, the biological activity of oligopeptides could be interpreted rapidly based on the known TCM protein sequence. The study provides the methodology basis for rapidly and efficiently implementing the mechanism analysis of TCM oligopeptides.

Molecular cloning and characterisation of scavenger receptor class B in pearl oyster Pinctada fuctada martensii

Background: Molluscs can accumulate carotenoids in their body tissues by predominantly feeding on aquatic plant sources. Carotenoid transport and absorption are determined by the regulation of various proteins such as Scavenger receptor class B(SR-BI). We report the identification and characterisation of pearl oyster Pinctada fuctada martensii SR-BI (PmSR-BI). The correlation between total carotenoid content (TCC) and gene expression was also estimated. Results: The full-length cDNA of PmSR-BI was 1828 bp, including an open-reading frame encoding of 1518 bp with a pI value of 5.83. PmSR-BI protein contains a hydrophobic CD36 domain and four centrally clustered cysteine residues for the arrangement of disulphide bridges. The deduced amino acid sequence had an identity of 30% to 60% with the SR-B of other organisms. Reverse transcription polymerase chain reaction analysis showed that mRNA transcripts were expressed in multiple tissues of adult pearl oyster. A higher expression of PmSR-BI gene was observed in the hepatopancreas than in the adductor muscle, gill and mantle. The TCC and gene expression of PmSR-BI were significantly correlated (P b 0.05), with a correlation coefficient of 0.978. Conclusions: The results suggested that PmSR-BI is involved in the absorption of carotenoids in the pearl oyster P. fuctada martensii.

A Novel Matrix Protein, PfY2, Functions as a Crucial Macromolecule during Shell Formation.

Biomineralization, including shell formation, is dedicatedly regulated by matrix proteins. PfY2, a matrix protein detected in the ethylene diamine tetraacetic acid (EDTA)-soluble fraction from both prismatic layer and nacreous layer, was discovered by our group using microarray. It may play dual roles during biomineralization. However, the molecular mechanism is still unclear. In this research, we studied the function of PfY2 on crystallization in vivo and in vitro, revealing that it might be a negative regulator during shell formation. Notching experiment indicated that PfY2 was involved in shell repairing and regenerating process. Repression of PfY2 gene affected the structure of prismatic and nacreous layer simultaneously, confirming its dual roles in shell formation. Recombinant protein rPfY2 significantly suppressed CaCO3 precipitation rate, participated in the crystal nucleation process, changed the morphology of crystals and inhibited the transformation of amorphous calcium carbonate (ACC) to stable calcite or aragonite in vitro. Our results may provide new evidence on the biomineralization inhibition process.

The AP-1 transcription factor homolog Pf-AP-1 activates transcription of multiple biomineral proteins and potentially participates in Pinctada fucata biomineralization.

Activator protein-1 (AP-1) is an important bZIP transcription factor that regulates a series of physiological processes by specifically activating transcription of several genes, and one of its well-chartered functions in mammals is participating in bone mineralization. We isolated and cloned the complete cDNA of a Jun/AP-1 homolog from Pinctada fucata and called it Pf-AP-1. Pf-AP-1 had a highly conserved bZIP region and phosphorylation sites compared with those from mammals. A tissue distribution analysis showed that Pf-AP-1 was ubiquitously expressed in P. fucata and the mRNA level of Pf-AP-1 is extremely high in mantle. Pf-AP-1 expression was positively associated with multiple biomineral proteins in the mantle. The luciferase reporter assay in a mammalian cell line showed that Pf-AP-1 significantly up-regulates the transcriptional activity of the promoters of KRMP, Pearlin, and Prisilkin39. Inhibiting the activity of Pf-AP-1 depressed the expression of multiple matrix proteins. Pf-AP-1 showed a unique expression pattern during shell regeneration and pearl sac development, which was similar to the pattern observed for biomineral proteins. These results suggest that the Pf-AP-1 AP-1 homolog is an important transcription factor that regulates transcription of several biomineral proteins simultaneously and plays a role in P. fucata biomineralization, particularly during pearl and shell formation.

[Identication of pearl powder and conch powder from different origins by differential scanning calorimetry].

The paper is aimed to establish a methods for identication of pearl powder and conch powder from different origins. Hermetic aluminum pan was used to encapsulate samples. The optimal testing conditions were: heating rate 10 degrees C x min(-1), sample weight 3 mg and nitrogen gas flow rate 40 mL x min(-1). The enthalpy values of pearl powder and conch powder was obvious different. Identication of pearl powder and conch powder by DSC is a practical method for its accuracy, convenience and practificality.

Cloning and identification of a YY-1 homolog as a potential transcription factor from Pinctada fucata.

Biomineralization is an important and ubiquitous process in organisms. The shell formation of mollusks is a typical biomineral physical activity and is used as a canonical model in biomineralization research. Most recent studies focused on the identification of matrix proteins involved in shell formation; however, little is known about their transcriptional regulation mechanism, especially the transcription factors involved in shell formation. In this study, we identified a homolog of the YY-1 transcriptional factor from Pinctada fucata, named Pf-YY-1, and characterized its expression pattern and biological functions. Pf-YY-1 has a typical zinc finger motif highly similar to those in humans, mice, and other higher organisms, which indicated its DNA-binding capability and its function as a transcription factor. Pf-YY-1 is ubiquitously expressed in many tissues, but at a higher level in the mantle, which suggested a role in biomineralization. The expression pattern of Pf-YY-1 during pearl sac development was quite similar to, and was synchronized with, those of Prisilkin-39, ACCBP, and other genes involved in biomineralization, which also suggested its function in biomineralization.

Ultra-performance liquid chromatography of amino acids for the quality assessment of pearl powder.

Pearls have been widely used as a traditional medicine, in cosmetics, and as a health food supplement in China since ancient times. However, the identification and quality assessment of pearl powder have been challenging tasks because of the similar morphological features and chemical composition of its common adulterants, especially conch powders. In this study, ultra-performance liquid chromatography was combined with pre-column derivatization to rapidly quantify 14 amino acids in pearl powder and its analogues. Based upon the quantification results, a quality criterion of a total amino acid content of not less than 1.10% was proposed for pearl powder. Principal component analysis indicated that leucine and phenylalanine were the amino acids characteristic for distinguishing between pearls and nacres. The area ratio of leucine to phenylalanine was demonstrated to be an effective diagnostic marker to discriminate freshwater cultured pearls, natural seawater pearls, and nacres. The proposed method, involving both the qualitative and quantitative aspects, was subsequently applied to quality assessment of pearl powders purchased commercially in various parts of China; eight out of 18 batches were deemed authentic and unadulterated. In the future, this analytical process should play a significant role in standardizing and providing quality control to the pearl powder market.

Identification of ligament intra-crystalline peptide (LICP) from the hinge ligament of the bivalve, Pinctada fucata.

The hinge ligament of the bivalve is an important hard tissue that functions to open and close the shells. The ligament contains a fibrous structure consisting of aragonite crystals surrounded by dense organic matrices. Although many matrix proteins have been identified from various shell microstructures in previous works, ligament-specific matrix proteins have not yet been reported. In this study, in order to reveal the formation mechanism of the fibrous aragonite crystals in the ligament of Pinctada fucata, we identified a novel, small acidic peptide, named ligament intra-crystalline peptide (LICP), from the aragonite crystal of the ligament that had been pre-treated with sodium hypochlorite to remove the inter-crystalline organic matrices. LICP consists of 10 amino acid residues with N-terminal pyroglutamic acid. The result of cDNA cloning showed that the cDNA encodes another putative 10-residue peptide at the C-terminal end of LICP. LICP showed inhibitory activity on calcium carbonate precipitation, while the synthetic 10-residue peptide from the C-terminal sequence of proLICP did not. We also noted that the TEM and SEM observations of aragonite crystals formed by the in vitro crystallization experiment showed that LICP inhibited the growth of aragonite crystal to stop elongation in the c-axis direction. These results suggested that LICP has a role of regulating the formation of the aragonite crystals in the ligament.

Molecular characterization of tumor necrosis factor receptor-associated factor 6 (TRAF6) in pearl oyster Pinctada martensii.

Tumor necrosis factor receptor-associated factor 6 (TRAF6) is a key signaling adaptor molecule for tumor necrosis factor receptor superfamily and Toll-like receptor/interleukin-1 receptor family members. It signals the upstream receptors and is involved in a wide range of biological functions, such as immunity and bone metabolism. In this report, the TRAF6 gene from the pearl oyster Pinctada martensii (designated as PmTRAF6) was identified and characterized. The obtained full-length PmTRAF6 cDNA was 2273 bp, containing a 5'-untranslated region (UTR) of 297 bp, a 3'-UTR of 128 bp with a 42-bp poly (A) tail, and an open reading frame of 1848 bp that encoded 616-amino acid residues. The deduced protein sequence of PmTRAF6 contained a conserved TRAF family motif including a RING-type zinc finger, two TRAF-type zinc fingers, and a coiled-coil region followed by one meprin and TRAF homology domain. Multiple-sequence alignment indicated that TRAF6 was highly conserved among species, and PmTRAF6 showed 53% sequence identity to Azumapecten farreri and Mizuhopecten yessoensis. Furthermore, an amino acid sequence containing a low-complexity region was inserted in the TRAF6s from mollusk. Quantitative real-time polymerase chain reaction analysis demonstrated that PmTRAF6 was constitutively expressed in all tissues studied, with the most abundant mRNA expression in hepatopancreas and gill in P. martensii. After lipopolysaccharide stimulation, the expression of PmTRAF6 mRNA was dramatically upregulated. These results suggested that the obtained PmTRAF6 was a member of the TRAF6 family and perhaps involved in the innate immune response of pearl oyster.

Antigen specific immune enhancement of innate and acquired immunity by pearl in ashed form.

The present study evaluated mineral compound, pearl in ashed form [PAF], for its potential as oral immunomodulator. ICP-MS, atomic absorption spectroscopy, CHNS analysis and XRD analysis were used for characterization of PAF. Surface antigen markers (TLR-2/4 and CD-80/86) were studied by flow cytometry. At dose concentration of 25, 50, 100 and 500 µg/kg body wt., administrated orally for 10 days, TLR-2 expression on murine peritoneal macrophage increased while TLR-4 expression was reduced as compared to control. There was an increase in OVA and mitogen (Con-A) specific lymphocyte proliferation in OVA immunized mice. Also, level of both Th1 (IL-2/IFN-γ) and Th2 (IL-4/IL-10) cytokines, and level and titer of total IgG, IgG1, IgG2a and IgG2b of OVA immunized mice significantly increased. The level of Inflammatory cytokines (IL-1ß and TNF-α) did not increase significantly. Enhancement in T and B cell immune responses may be possibly due to significantly enhanced expression of CD-80 and CD-86 co-stimulatory signals as observed using flow cytometry. Also, enhanced phagocytic activity and DTH response exhibit stimulatory effect of PAF on innate and cell mediated immune response. Histopathological analysis of liver, kidney and spleen and analysis of other toxicity parameters, such as effect on body weight, lymphoid organ weight and cellularity, revealed PAF to exhibit no toxic effects. PAF seems to be a promising balanced Th1 and Th2 directing immunomodulator, possibly activating TLR2 through TIR domain-containing adaptor inducing interferon ß (TRIF)-dependent pathway that leads to T-cell activation and promotes effective immune responses and may find useful application clinically.