Chlamydia trachomatis plasmid-encoding Pgp3 protein induces secretion of distinct inflammatory signatures from HeLa cervical epithelial cells.

BACKGROUND: Genital Chlamydia trachomatis infection is the most common bacterial sexual transmitted disease that causes severe complications including pelvic inflammatory disease, ectopic pregnancy, and infertility in females. The Pgp3 protein encoded by C. trachomatis plasmid has been speculated to be an important player in chlamydial pathogenesis. However, the precise function of this protein is unknown and thus remains to be thoroughly investigated. METHODS: In this study, we synthesized Pgp3 protein for in vitro stimulation in the Hela cervical carcinoma cells. RESULTS AND CONCLUSION: We showed that Pgp3 induced prominent expression of host inflammatory cytokine genes including interleukin-6 (IL-6), IL-8, tumor necrosis factor alpha-induced protein 3 (TNFAIP3), and chemokine C-X-C motif ligand 1 (CXCL1), implying a possible role of Pgp3 in modulating the inflammatory reaction in the host.

Comparative expression of pro-inflammatory and apoptotic biosignatures in chronic HBV-infected patients with and without liver cirrhosis.

The interplay of immune mediators is paramount to optimal host anti-viral immune responses, especially against chronic hepatitis B virus (HBV) infection. Here, we investigated the dynamic changes in host immune responses in chronic HBV-infected individuals with and without liver cirrhosis by examining the signatures of apoptosis and plasma levels of pro-inflammatory cytokines, chemokines, and cytotoxic proteins. A total of 40 chronic HBV patients with and without liver cirrhosis were studied for plasma levels of immune mediators, and signatures of apoptosis in peripheral blood mononuclear cells (PBMCs). The intracellular concentrations of reactive oxygen species (ROS) in patients with chronic HBV with liver cirrhosis was relatively higher as compared to chronic HBV patients. The onset of apoptosis was sustained due to ongoing liver inflammation in concert with plasma TNF-α and IL-6 levels. Plasma VEGF was upregulated among chronic HBV patients with liver cirrhosis, whereas CCL2, CCL5 and granzyme B levels were down-regulated. High levels of ROS, IL-6 and TNF-α correlated with ongoing inflammation among chronic HBV patients with liver cirrhosis, which likely attributed to the expression of biosignatures of apoptosis and activation in immune cells.

Seroprevalence of Nipah Virus Infection in Peninsular Malaysia.

Nipah virus (NiV) outbreak occurred in Malaysia in 1998. The natural host reservoir for NiV is Pteropus bats, which are commonly found throughout Malaysia. Humans become infected when NiV spills over from the reservoir species. In this study, NiV serosurveillance in Peninsular Malaysia, particularly among the indigenous population, was performed. The collected samples were tested for presence of NiV antibodies using a comparative indirect enzyme-linked immunosorbent assay based on the recombinant NiV nucleocapsid (rNiV-N) protein. We found that 10.73% of the participants recruited in this study had antibodies against rNiV-N, suggesting possible exposure to NiV.

CD8+ T cells of chronic HCV-infected patients express multiple negative immune checkpoints following stimulation with HCV peptides.

Hepatitis C virus (HCV)-specific CD4+ and CD8+ T cells are key to successful viral clearance in HCV disease. Accumulation of exhausted HCV-specific T cells during chronic infection results in considerable loss of protective functional immune responses. The role of T-cell exhaustion in chronic HCV disease remains poorly understood. Here, we studied the frequency of HCV peptide-stimulated T cells expressing negative immune checkpoints (PD-1, CTLA-4, TRAIL, TIM-3 and BTLA) by flow cytometry, and measured the levels of Th1/Th2/Th17 cytokines secreted by T cells by a commercial Multi-Analyte ELISArray™ following in vitro stimulation of T cells using HCV peptides and phytohemagglutinin (PHA). HCV peptide-stimulated CD4+ and CD8+ T cells of chronic HCV (CHC) patients showed significant increase of CTLA-4. Furthermore, HCV peptide-stimulated CD4+ T cells of CHC patients also displayed relatively higher levels of PD-1 and TRAIL, whereas TIM-3 was up-regulated on HCV peptide-stimulated CD8+ T cells. Whereas the levels of IL-10 and TGF-ß1 were significantly increased, the levels of pro-inflammatory cytokines IL-2, TNF-α, IL-17A and IL-6 were markedly decreased in the T cell cultures of CHC patients. Chronic HCV infection results in functional exhaustion of CD4+ and CD8+ T cells likely contributing to viral persistence.

Temporal proteomic profiling of Chlamydia trachomatis-infected HeLa-229 human cervical epithelial cells.

Chlamydia trachomatis is the leading causative agent of bacterial sexually transmitted infections worldwide which can lead to female pelvic inflammatory disease and infertility. A greater understanding of host response during chlamydial infection is essential to design intervention technique to reduce the increasing incidence rate of genital chlamydial infection. In this study, we investigated proteome changes in epithelial cells during C. trachomatis infection by using an isobaric tags for relative and absolute quantitation (iTRAQ) labeling technique coupled with a liquid chromatography-tandem mass spectrometry (LC-MS(3) ) analysis. C. trachomatis (serovar D, MOI 1)-infected HeLa-229 human cervical carcinoma epithelial cells (at 2, 4 and 8 h) showed profound modifications of proteome profile which involved 606 host proteins. MGST1, SUGP2 and ATXN10 were among the top in the list of the differentially upregulated protein. Through pathway analysis, we suggested the involvement of eukaryotic initiation factor 2 (eIF2) and mammalian target of rapamycin (mTOR) in host cells upon C. trachomatis infection. Network analysis underscored the participation of DNA repair mechanism during C. trachomatis infection. In summary, intense modifications of proteome profile in C. trachomatis-infected HeLa-229 cells indicate complex host-pathogen interactions at early phase of chlamydial infection.

Oral vaccine of Lactococcus lactis harbouring pandemic H1N1 2009 haemagglutinin1 and nisP anchor fusion protein elevates anti-HA1 sIgA levels in mice.

OBJECTIVE: An oral lactococcal-based vaccine which haboured the haemagglutinin1 (HA1) antigen fused to nisP anchor protein for the purpose of surface displaying the HA1 antigen was developed against H1N1 virus. RESULTS: Recombinant L. lactis strains expressed HA1-nisP fusion proteins when induced with nisin, as confirmed through western blotting. However, immunofluorescense did not detect any surface-displayed proteins, suggesting that the protein was either unsuccessfully translocated or improperly displayed. Despite this, oral administration of recombinant L. lactis strains to BALB/c mice revealed that significant levels of anti-HA1 sIgA antibodies were detected in mice fecal suspension samples of mice group NZ9000 (pNZ:HN) when compared to the negative control NZ9000 (pNZ8048) group. CONCLUSION: Specific anti-HA1 sIgA antibodies were locally produced and live recombinant lactococcal vaccine was able to elicit humoral response of BALB/c mice despite unsuccessful surface display of the HA1 epitope.

Full genome SNP-based phylogenetic analysis reveals the origin and global spread of Brucella melitensis.

BACKGROUND: Brucellosis is an important zoonotic disease that affects both humans and animals. We sequenced the full genome and characterised the genetic diversity of two Brucella melitensis isolates from Malaysia and the Philippines. In addition, we performed a comparative whole-genome single nucleotide polymorphism (SNP) analysis of B. melitensis strains collected from around the world, to investigate the potential origin and the history of the global spread of B. melitensis. RESULTS: Single sequencing runs of each genome resulted in draft genome sequences of MY1483/09 and Phil1136/12, which covered 99.85% and 99.92% of the complete genome sequences, respectively. The B. melitensis genome sequences, and two B. abortus strains used as the outgroup strains, yielded a total of 13,728 SNP sites. Phylogenetic analysis using whole-genome SNPs and geographical distribution of the isolates revealed spatial clustering of the B. melitensis isolates into five genotypes, I, II, III, IV and V. The Mediterranean strains, identified as genotype I, occupied the basal node of the phylogenetic tree, suggesting that B. melitensis may have originated from the Mediterranean regions. All of the Asian B. melitensis strains clustered into genotype II with the SEA strains, including the two isolates sequenced in this study, forming a distinct clade denoted here as genotype IId. Genotypes III, IV and V of B. melitensis demonstrated a restricted geographical distribution, with genotype III representing the African lineage, genotype IV representing the European lineage and genotype V representing the American lineage. CONCLUSION: We showed that SNPs retrieved from the B. melitensis draft full genomes were sufficient to resolve the interspecies relationships between B. melitensis strains and to discriminate between the vaccine and endemic strains. Phylogeographic reconstruction of the history of B. melitensis global spread at a finer scale by using whole-genome SNP analyses supported the origin of all B. melitensis strains from the Mediterranean region. The possible global distribution of B. melitensis following the ancient trade routes was also consistent with whole-genome SNP phylogeny. The whole genome SNP phylogenetics analysis, hence is a powerful tool for intraspecies discrimination of closely related species.

T-cell receptor signaling induces proximal Runx1 transactivation via a calcineurin-NFAT pathway.

Runx1 transcription factor is a key player in the development and function of T cells. Runx1 transcripts consist of two closely related isoforms (proximal and distal Runx1) whose expressions are regulated by different promoters. Which Runx1 isoform is expressed appears to be tightly regulated. The regulatory mechanism for differential transcription is, however, not fully understood. In this study, we investigated the regulation of the proximal Runx1 promoter in T cells. We showed that proximal Runx1 was expressed at a low level in naïve T cells from C57BL/6 mice, but its expression was remarkably induced upon T-cell activation. In the promoter of proximal Runx1, a highly conserved region was identified which spans from -412 to the transcription start site and harbors a NFAT binding site. In a luciferase reporter assay, this region was found to be responsive to T-cell activation through Lck and calcineurin pathways. Mutagenesis studies and chromatin immunoprecipitation assay indicated that the NFAT site was essential for NFAT binding and transactivation of the proximal Runx1 promoter. Furthermore, TCR signaling-induced expression of proximal Runx1 was blocked by treatment of cells with cyclosporin A. Together, these results demonstrate that the calcineurin-NFAT pathway regulates proximal Runx1 transcription upon TCR stimulation.

A systematic review on Nipah virus: global molecular epidemiology and medical countermeasures development.

Nipah virus (NiV) is an emerging pathogen that causes encephalitis and a high mortality rate in infected subjects. This systematic review aimed to comprehensively analyze the global epidemiology and research advancements of NiV to identify the key knowledge gaps in the literature. Articles searched using literature databases, namely PubMed, Scopus, Web of Science, and Science Direct yielded 5,596 articles. After article screening, 97 articles were included in this systematic review, comprising 41 epidemiological studies and 56 research developments on NiV. The majority of the NiV epidemiological studies were conducted in Bangladesh, reflecting the country's significant burden of NiV outbreaks. The initial NiV outbreak was identified in Malaysia in 1998, with subsequent outbreaks reported in Bangladesh, India, and the Philippines. Transmission routes vary by country, primarily through pigs in Malaysia, consumption of date palm juice in Bangladesh, and human-to-human in India. However, the availability of NiV genome sequences remains limited, particularly from Malaysia and India. Mortality rates also vary according to the country, exceeding 70% in Bangladesh, India, and the Philippines, and less than 40% in Malaysia. Understanding these differences in mortality rate among countries is crucial for informing NiV epidemiology and enhancing outbreak prevention and management strategies. In terms of research developments, the majority of studies focused on vaccine development, followed by phylogenetic analysis and antiviral research. While many vaccines and antivirals have demonstrated complete protection in animal models, only two vaccines have progressed to clinical trials. Phylogenetic analyses have revealed distinct clades between NiV Malaysia, NiV Bangladesh, and NiV India, with proposals to classify NiV India as a separate strain from NiV Bangladesh. Taken together, comprehensive OneHealth approaches integrating disease surveillance and research are imperative for future NiV studies. Expanding the dataset of NiV genome sequences, particularly from Malaysia, Bangladesh, and India will be pivotal. These research efforts are essential for advancing our understanding of NiV pathogenicity and for developing robust diagnostic assays, vaccines and therapeutics necessary for effective preparedness and response to future NiV outbreaks.

Outbreak of human infection with Sarcocystis nesbitti, Malaysia, 2012.

An outbreak of fever associated with myalgia and myositis occurred in 2012 among 89 of 92 college students and teachers who visited Pangkor Island, Malaysia. The Sarcocystis nesbitti 18S rRNA gene and sarcocysts were obtained from muscle tissues of 2 students. Our findings indicate emergence of S. nesbitti infections in humans in Malaysia.

Anesthesia in patients with Brugada syndrome: two case reports.

BACKGROUND: Brugada syndrome is a rare disease. It causes sudden cardiac arrest, which is a serious life-threatening event. Sudden cardiac death mostly results from coronary artery disease. However, patients with Brugada syndrome show normal cardiac anatomy and no evidence of ischemia or electrolyte imbalance. Anesthesia in patients with Brugada syndrome is challenging due to its unpredictable nature, and is worth our attention. CASE PRESENTATION: We report two cases of Brugada syndrome during anesthesia. In case one, a 31-year-old Filipino laborer was scheduled for laparoscopic appendectomy. The patient denied any preexisting cardiac disease. The preoperative vital signs were stable, with mild fever of 37.9 °C. The operation was smooth. During the emergence period, the patient suffered from sudden onset of ventricular tachycardia. After resuscitation, the cardiac rhythm returned to normal. Later, he was confirmed to have a genetic trait of Brugada syndrome. In case two, a young Taiwanese patient with pre-diagnosed Brugada syndrome underwent an operation. The perioperative precautions were taken to prevent the occurrence of ventricular arrhythmia. The surgery was uneventful. CONCLUSIONS: Brugada syndrome, although rare, has the highest incidence in South East Asian healthy young males. It brings attention to possible fatal cardiac arrhythmia in this population. Careful preoperative evaluation and perioperative management can help reduce the harmful outcome of the disease and prevent any untoward events.

Chlamydia Infection Remodels Host Cell Mitochondria to Alter Energy Metabolism and Subvert Apoptosis.

Chlamydia infection represents an important cause for concern for public health worldwide. Chlamydial infection of the genital tract in females is mostly asymptomatic at the early stage, often manifesting as mucopurulent cervicitis, urethritis, and salpingitis at the later stage; it has been associated with female infertility, spontaneous abortion, ectopic pregnancy, and cervical cancer. As an obligate intracellular bacterium, Chlamydia depends heavily on host cells for nutrient acquisition, energy production, and cell propagation. The current review discusses various strategies utilized by Chlamydia in manipulating the cell metabolism to benefit bacterial propagation and survival through close interaction with the host cell mitochondrial and apoptotic pathway molecules.

Immunomodulatory proteins from hookworms reduce cardiac inflammation and modulate regulatory responses in a mouse model of chronic Trypanosoma cruzi infection.

Introduction: Hookworms are parasitic helminths that secrete a variety of proteins that induce anti-inflammatory immune responses, stimulating increased CD4 + Foxp3+ regulatory T cells and IL-10 production. Hookworm-derived recombinant proteins AIP-1 and AIP-2 have been shown to reduce inflammation in mouse models of inflammatory bowel disease and inflammatory airway disease by inducing CD4+Foxp3+ cells and IL-10 production. In contrast, chronic infection with the protozoal parasite Trypanosoma cruzi, the causative agent of Chagas disease, leads to chronic inflammation in tissues. Persistence of the parasites in tissues drives chronic low-grade inflammation, with increased infiltration of inflammatory cells into the heart, accompanied by increased production of inflammatory cytokines. There are no current antiparasitic drugs that effectively reduce or prevent chronic myocarditis caused by the onset of Chagas disease, thus new therapies are urgently needed. Therefore, the impact of AIP-1 and AIP-2 on myocarditis was investigated in a mouse model of chronic T. cruzi infection. Methods: Female BALB/c mice infected with bioluminescent T. cruzi H1 strain trypomastigotes for 70 days were treated once daily for 7 days with 1mg/kg AIP-1 or AIP-2 protein by intraperitoneal injection. Control mice were left untreated or treated once daily for 14 days with 25mg/kg aspirin in drinking water. At 84 days of infection, splenocytes, cardiac tissue and serum were collected for evaluation. Results: Treatment with both AIP-1 and AIP-2 proteins significantly reduced cardiac cellular infiltration, and reduced cardiac levels of IFNγ, IL-6 and IL-2. AIP-2 treatment reduced cardiac expression of COX-2. Further, while incubation with AIP-1 and AIP-2 proteins did not induce a significant upregulation of an immunoregulatory phenotype in dendritic cells (DC), there was a modest upregulation of CD11c +CD11b+MHCII+SIRPα+ expression, suggesting a regulatory phenotype. Ex-vivo stimulation of splenocytes from the treatment groups with AIP-1 loaded DC induced reduced levels of cytotoxic and pro-inflammatory T cells, stimulation with AIP-2 loaded DC specifically induced enhanced levels of CD4+CD25+Foxp3+ regulatory T cells among treatment groups. Discussion: All in vivo and in vitro results demonstrate that hookworm-derived AIP-1 and AIP-2 proteins reduce T. cruzi induced cardiac inflammation, possibly through multiple anti-inflammatory mechanisms.

The Immunobiology of Nipah Virus.

Nipah virus (NiV) is a highly lethal zoonotic paramyxovirus that emerged in Malaysia in 1998. It is a human pathogen capable of causing severe respiratory infection and encephalitis. The natural reservoir of NiV, Pteropus fruit bats, remains a continuous virus source for future outbreaks, although infection in the bats is largely asymptomatic. NiV provokes serious disease in various mammalian species. In the recent human NiV outbreaks in Bangladesh and India, both bats-to-human and human-to-human transmissions have been observed. NiV has been demonstrated to interfere with the innate immune response via interferon type I signaling, promoting viral dissemination and preventing antiviral response. Studies of humoral immunity in infected NiV patients and animal models have shown that NiV-specific antibodies were produced upon infection and were protective. Studies on cellular immunity response to NiV infection in human and animal models also found that the adaptive immune response, specifically CD4+ and CD8+ T cells, was stimulated upon NiV infection. The experimental vaccines and therapeutic strategies developed have provided insights into the immunological requirements for the development of successful medical countermeasures against NiV. This review summarizes the current understanding of NiV pathogenesis and innate and adaptive immune responses induced upon infection.

Isolation of Streptococcus cuniculi from corneal lesion in laboratory-raised mice.

Corneal lesions appearing as white mass beneath intact epithelium, with ocular discharge in one mouse, was observed in a batch of laboratory-raised BALB/c mice (n=9 of 56). The affected mice remained active, well-groomed and had normal appetite. Isolates recovered from swab cultures of the external and internal contents of the eye had partial 16S rRNA gene sequence of 99.1% similarity to Streptococcus cuniculi. No previous report of S. cuniculi infection in laboratory rodents has been presented. The isolate was susceptible to all antibiotics tested. We suggest S. cuniculi is an opportunistic bacteria in laboratory mice but are uncertain of its source. Our findings revealed that S. cuniculi is able to colonize laboratory mice and should be considered when mice present with eye lesion or ocular discharge.

Characterization of Nipah virus from naturally infected Pteropus vampyrus bats, Malaysia.

We isolated and characterized Nipah virus (NiV) from Pteropus vampyrus bats, the putative reservoir for the 1998 outbreak in Malaysia, and provide evidence of viral recrudescence. This isolate is monophyletic with previous NiVs in combined analysis, and the nucleocapsid gene phylogeny species.

Copro-molecular study of Entamoeba infection among the indigenous community in Malaysia: A first report on the species-specific prevalence of Entamoeba in dogs.

BACKGROUND: Entamoeba is a free-living protozoan parasitic species that infect a variety of hosts. In humans, Entamoeba histolytica is the causative agent of amoebiasis. Entamoeba species has also been reported in dogs. However, little is known about the molecular epidemiology and the specific species of this parasite in dogs globally, including Malaysia. As dogs are important companion animals for the indigenous community, and close contact with dogs is part of the natural living conditions for this community, this study aims to determine the prevalence and molecular epidemiology of Entamoeba species in human and dogs in Malaysia. METHOD: The presence of Entamoeba species was examined in 504 fresh fecal samples, collected randomly from 411 humans and 93 dogs using microscopy and polymerase chain reaction (PCR) amplifying 16 s ribosomal RNA (rRNA). Data was analyzed using appropriate statistical analysis. RESULTS: The microscopy data showed an overall occurrence of Entamoeba species of 26.3% (108/411) and 36.6% (34/93) in humans and dogs respectively. In humans, the most common species was a single infection of E. dispar (26.5%; 13/49), followed by E. histolytica and E. moshkovskii, (20.4% for each species respectively). Double infection of E. dispar + E. moshkovskii was detected at 10.2%, followed by E. dispar + E. histolytica (8.2%) and E. moshkovskii and E. histolytica (6.1%). 8.2% of the samples had triple infection with all three species. In animals, E. moshkovskii (46.7%) was the most common species detected, followed by E. histolytica, and E. dispar, at 20.0% and 13.3% respectively. Double infection with E. moshkovskii + E. histolytica and a triple infection were found in 2 samples (13.3%) and 1 (6.7%) sample respectively. Risk factor analysis showed that members of the community who used untreated water were more prone to be infected with Entamoeba. CONCLUSION: This study provides information on the species-specific occurrence of Entamoeba infection, the potential risk factors and their zoonotic potential to humans. This is the first report to describe the molecular occurrence of Entamoeba species in dogs in Malaysia. The presence of pathogenic Entamoeba species implies that dogs could be a reservoir or mechanical host for human amoebiasis. Further studies need to be conducted to better understand the transmission dynamics and public health significance of Entamoeba species in human and animal hosts.

IncobotulinumtoxinA for the Treatment of Glabellar Frown Lines: A Prospective, Multicenter, Single-arm Study in Taiwan.

Objective: We assessed clinical effectiveness, longevity of treatment effects, and patient satisfaction with incobotulinumtoxinA for glabellar frown lines (GFL) treatment in Asian patients. Design, Setting, and Participants: This was a prospective, multicenter, single-arm, open-label study at six sites in Taiwan. Patients aged 20 to 65 years with mild to very severe GFLs (Merz scale: 1-4 points) were eligible; 45 patients [including 23 BoNT/A-naïve and 22 previously-treated ("switch") patients were enrolled. Patients received intramuscular incobotulinumtoxinA injection at up to five injection points. Total doses ranged from 12 to 20U. Measurements: Investigators assessed improvements in dynamic GFLs at Days 14 and 120 using the validated five-point Merz scale (0=no lines; 4=very severe lines). Treatment satisfaction was self-reported by patients via questionnaire. Results: All patients showed excellent response to treatment in that Merz scores at Day 14 were 0 or 1 point(s). Both groups showed a mean improvement of 2.9 points; the response rate (1-point improvement or more from baseline) was 100 percent. GFL improvement was maintained over at least four months in both groups (mean improvements at Day 120: 1.5 points, naïve; 1.7 points, switch). Patient satisfaction ratings remained high (almost 100% in both groups) throughout the study. There were no statistically significant differences between groups regarding treatment satisfaction or GFL improvement (Merz score) at Days 14 and 120. No adverse events occurred. Conclusion: In Asian patients, incobotulinumtoxinA treatment for dynamic GFLs is effective and long lasting, with no expected differences between BoNT/A-naïve patients and those switching from other BoNT/As. IncobotulinumtoxinA yields consistent and natural-looking results for first and subsequent treatments.

Diversity of endocervical microbiota associated with genital Chlamydia trachomatis infection and infertility among women visiting obstetrics and gynecology clinics in Malaysia.

The cervical microbiota constitutes an important protective barrier against the invasion of pathogenic microorganisms. A disruption of microbiota within the cervical milieu has been suggested to be a driving factor of sexually transmitted infections. These include Chlamydia trachomatis which frequently causes serious reproductive sequelae such as infertility in women. In this study, we profiled the cervical microbial composition of a population of 70 reproductive-age Malaysian women; among which 40 (57.1%) were diagnosed with genital C. trachomatis infection, and 30 (42.8%) without C. trachomatis infection. Our findings showed a distinct compositional difference between the cervical microbiota of C. trachomatis-infected subjects and subjects without C. trachomatis infection. Specifically, significant elevations of mostly strict and facultative anaerobes such as Streptococcus, Megasphaera, Prevotella, and Veillonella in the cervical microbiota of C. trachomatis-positive women were detected. The results from the current study highlights an interaction of C. trachomatis with the environmental microbiome in the endocervical region.

Nipah Virus Infection of Immature Dendritic Cells Increases Its Transendothelial Migration Across Human Brain Microvascular Endothelial Cells.

Nipah virus (NiV) can infect multiple organs in humans with the central nervous system (CNS) being the most severely affected. Currently, it is not fully understood how NiV spreads throughout the body. NiV has been shown to infect certain leukocyte populations and we hypothesized that these infected cells could cross the blood-brain barrier (BBB), facilitating NiV entry into the CNS. Here, three leukocyte types, primary immature dendritic cells (iDC), primary monocytes (pMO), and monocytic cell line (THP-1), were evaluated for permissiveness to NiV. We found only iDC and THP-1 were permissive to NiV. Transendothelial migration of mock-infected and NiV-infected leukocytes was then evaluated using an in vitro BBB model established with human brain microvascular endothelial cells (HBMEC). There was approximately a threefold increase in migration of NiV-infected iDC across endothelial monolayer when compared to mock-infected iDC. In contrast, migration rates for pMO and THP-1 did not change upon NiV infection. Across TNF-α-treated endothelial monolayer, there was significant increase of almost twofold in migration of NiV-infected iDC and THP-1 over mock-infected cells. Immunofluorescence analysis showed the migrated NiV-infected leukocytes retained their ability to infect other cells. This study demonstrates for the first time that active NiV infection of iDC and THP-1 increased their transendothelial migration activity across HBMEC and activation of HBMEC by TNF-α further promoted migration. The findings suggest that NiV infection of leukocytes to disseminate the virus via the "Trojan horse" mechanism is a viable route of entry into the CNS.