Current prevalence and geographic distribution of helminth infections in the parasitic endemic areas of rural Northeastern Thailand.

BACKGROUND: Helminth infection is a global health issue that not only causes acute helminthiasis but long-term infection may lead to complicated symptoms as well as severe complications. The World Health Organization cooperated with the Ministry of Public Health in many countries, particularly where high prevalence, spending a lot of resources for limiting the infection. In Thailand, the incidence of parasitic helminth infections was continuously declined in the last few decades according to several campaigns for parasitic elimination. However, the rural community in the northeast of Thailand where the highest prevalence of the country still needs to be monitored. This present study aims to report the current prevalence of parasitic helminth infections in Nakhon Ratchasima and Chaiyaphum provinces where sharing a huge area of the northeastern region of Thailand but only a few studies have been published. METHODS: The stool specimens were collected from 11,196 volunteers and processed by modified Kato-Katz thick smear, PBS-ethyl acetate concentration techniques, and PCR. The epidemiological data were collected, analyzed, and used for generating of parasitic hotspots. RESULTS: The results indicated that O. viverrini remains the major parasite in this area with a total prevalence of 5.05% followed by Taenia spp., Hookworms, T. trichiura, and Echinostoma spp., respectively. Mueang district of Chaiyaphum province has the highest prevalence especially O. viverrini with a prevalence of 7.15% that higher than the latest national surveillance. Interestingly, the prevalence of O. viverrini was hugely reported (more than 10%) in five subdistricts. The geographic localization of O. viverrini infections revealed that a lot of water reservoirs such as the lakes or branches of the river in the two-most prevalent subdistricts. Our finding indicated that gender and age were insignificantly different. CONCLUSION: This finding suggested that the parasitic helminth infection in the rural areas of northeast of Thailand remains high and the housing location is a major contributing factor for the parasitic infection.

The blood-brain barrier internalises Cryptococcus neoformans via the EphA2-tyrosine kinase receptor.

Cryptococcus neoformans is an opportunistic fungal pathogen that causes life-threatening meningitis most commonly in populations with impaired immunity. Here, we resolved the transcriptome of the human brain endothelium challenged with C. neoformans to establish whether C. neoformans invades the CNS by co-opting particular signalling pathways as a means to promote its own entry. Among the 5 major pathways targeted by C. neoformans, the EPH-EphrinA1 (EphA2) tyrosine kinase receptor-signalling pathway was examined further. Silencing the EphA2 receptor transcript in a human brain endothelial cell line or blocking EphA2 activity with an antibody or chemical inhibitor prevented transmigration of C. neoformans in an in vitro model of the blood-brain barrier (BBB). In contrast, treating brain endothelial cells with an EphA2 chemical agonist or an EphA2 ligand promoted greater migration of fungal cells across the BBB. C. neoformans activated the EPH-tyrosine kinase pathway through a CD44-dependent phosphorylation of EphA2, promoting clustering and internalisation of EphA2 receptors. Moreover, HEK293T cells expressing EphA2 revealed an association between EphA2 and C. neoformans that boosted internalisation of C. neoformans. Collectively, the results suggest that C. neoformans promotes EphA2 activity via CD44, and this in turn creates a permeable barrier that facilitates the migration of C. neoformans across the BBB.

Activity of the calcium channel pore Cch1 is dependent on a modulatory region of the subunit Mid1 in Cryptococcus neoformans.

Calcium (Ca(2+))-mediated signaling events in fungal pathogens such as Cryptococcus neoformans are central to physiological processes, including those that mediate stress responses and promote virulence. The Cch1-Mid1 channel (CMC) represents the only high-affinity Ca(2+) channel in the plasma membrane of fungal cells; consequently, cryptococci cannot survive in low-Ca(2+) environments in the absence of CMC. Previous electrophysiological characterization revealed that Cch1, the predicted channel pore, and Mid1, a binding partner of Cch1, function as a store-operated Ca(2+)-selective channel gated by depletion of endoplasmic reticulum (ER) Ca(2+) stores. Cryptococci lacking CMC did not survive ER stress, indicating its critical role in restoring Ca(2+) homeostasis. Despite the requirement for Mid1 in promoting Ca(2+) influx via Cch1, identification of the role of Mid1 remains elusive. Here we show that the C-terminal tail of Mid1 is a modulatory region that impinges on Cch1 channel activity directly and mediates the trafficking of Mid1 to the plasma membrane. This region consists of the last 24 residues of Mid1, and the functional expression of Mid1 in a human embryonic cell line (HEK293) and in C. neoformans is dependent on this domain. Substitutions of arginine (R619A) or cysteine (C621A) in the modulatory region failed to target Mid1 to the plasma membrane and prevented CMC activity. Interestingly, loss of a predicted protein kinase C (PKC)-phosphorylated serine residue (S605A) had no effect on Mid1 trafficking but did alter the kinetics of Cch1 channel activity. Thus, establishment of Ca(2+) homeostasis in C. neoformans is dependent on a modulatory domain of Mid1.

Microscopic and molecular epidemiology of gastrointestinal nematodes in dairy and beef cattle in Pak Chong district, Nakhon Ratchasima province, Thailand.

Background and Aim: Gastrointestinal (GI) nematode infection remains an important problem in livestock, particularly cattle. The infection may lead to serious health complications and affect animal products. The objective of this study was to investigate GI nematode infection and its associated risk factors in dairy and beef cattle farmed in Pak Chong District of Nakhon Ratchasima Province, northeast Thailand. Materials and Methods: Fecal specimens were collected from 101 dairy cattle and 100 beef cattle. Formalin-ethyl acetate concentration techniques were used to process the samples and the samples were observed under a light microscope. Samples were subjected to molecular identification of specific genera using conventional polymerase chain reaction and DNA sequencing. Results: The overall prevalence of GI nematode infection was 33.3%. The strongyle nematode was the most significant GI nematode in this area with a prevalence of 28.4%. The prevalence of strongyle nematodes was 58.0% in beef cattle and only 7.9% in dairy cattle. Trichuris spp. was another nematode found in both types of cattle with an overall prevalence of 5.0% with 9.0% in beef cattle and 1.0% in dairy cattle. The results of the epidemiological study indicate that the age of cattle, food, water sources, farming system, and housing floor are the most important risk factors. Among the strongyle nematodes, Ostertagia spp. was the most prevalent (82.0%), followed by Haemonchus spp. (62.3%) and Trichostrongylus spp. (8.2%), respectively. Conclusion: Infection with GI nematodes still exists in this area, particularly in beef cattle. Our reported data may benefit local parasitic control policies in the future.

Coproprevalence, seroprevalence, and geographic distribution of Fasciola spp. infection in beef and dairy cattle in Pak Chong highland, Nakhon-Ratchasima Province, Northeast Thailand.

Fasciola spp. is a major livestock parasite, especially in cattle, water buffalo, sheep, and goats. Infection reduces animal productivity, e.g., meat, dairy, wool and might cause death. In Thailand, reports of Fasciola spp. infection in livestock, especially dairy and beef cattle, are sparse. Pakchong district in Nakhon Ratchasima province is one of Thailand's largest farming areas for dairy and beef cattle, but the prevalence of Fasciola spp. infection has never been reported in this district. The landscape of this area is mainly a hilltop plateau with many water sources suitable for the development of lymnaeid snails, the intermediate host of Fasciola spp., which are essential for the parasite life cycle. This study surveyed the copro- and seroprevalence of Fasciola spp. infection in dairy and beef cattle farmed in Pakchong district by microscope-based examination, PCR, and indirect ELISA. Associated risk factors and geographic information data were collected and analyzed. Paired stool and serum samples were collected from 102 dairy cattle and 99 beef cattle from April to November 2021. Sample analyses demonstrated a high prevalence of Fasciola spp. infection, especially in beef cattle. The overall copro-prevalence was 5.97%, with 0.99% in dairy cattle and 11.11% in beef cattle. The overall seroprevalence was 23.88%, with 2.94% in dairy cattle and 45.45% in beef cattle. Moreover, the data indicated that infection status was not correlated with animal sex and age whereas consumption of natural grasses, water resources, housing floor, and farming system were significant risk factors. Data analysis by a geographic information system (GIS) demonstrated that an associated risk could be farmed in lowering areas, especially in Chan Thuck, Nong Sa Rai, and Khlong Muang subdistricts. In conclusion, this study reports the prevalence of Fasciola spp. infection in cattle in a major farming area of Thailand which could be beneficial for designing parasite control policies in this region as well as adapting this knowledge to other Fasciola spp. endemic areas.

Type I Cystatin Derived from Fasciola gigantica Suppresses Macrophage-Mediated Inflammatory Responses.

There is an inverse relationship between the high incidence of helminth infection and the low incidence of inflammatory disease. Hence, it may be that helminth molecules have anti-inflammatory effects. Helminth cystatins are being extensively studied for anti-inflammatory potential. Therefore, in this study, the recombinant type I cystatin (stefin-1) of Fasciola gigantica (rFgCyst) was verified to have LPS-activated anti-inflammatory potential, including in human THP-1-derived macrophages and RAW 264.7 murine macrophages. The results from the MTT assay suggest that rFgCyst did not alter cell viability; moreover, it exerted anti-inflammatory activity by decreasing the production of proinflammatory cytokines and mediators, including IL-1ß, IL-6, IL-8, TNF-α, iNOS, and COX-2 at the gene transcription and protein expression levels, as determined by qRT-PCR and Western blot analysis, respectively. Further, the secretion levels of IL-1ß, IL-6, and TNF-α determined by ELISA and the NO production level determined by the Griess test were decreased. Furthermore, in Western blot analysis, the anti-inflammatory effects involved the downregulation of pIKKα/ß, pIκBα, and pNF-κB in the NF-κB signaling pathway, hence reducing the translocation from the cytosol into the nucleus of pNF-κB, which subsequently turned on the gene of proinflammatory molecules. Therefore, cystatin type 1 of F. gigantica is a potential candidate for inflammatory disease treatment.

The structure-function analysis of the Mpr1 metalloprotease determinants of activity during migration of fungal cells across the blood-brain barrier.

Cryptococcal meningoencephalitis, the most common form of cryptococcosis, is caused by the opportunistic fungal pathogen, Cryptococcus neoformans. Molecular strategies used by C. neoformans to invade the central nervous system (CNS) have been the focus of several studies. Recently, the role of a novel secreted metalloprotease (Mpr1) in the pathogenicity of C. neoformans was confirmed by studies demonstrating that Mpr1 mediated the migration of fungal cells into the CNS. Given this central function, the aim here was to identify the molecular determinants of Mpr1 activity and resolve their role in the migration of cryptococci across the blood-brain barrier (BBB). The Mpr1 protein belongs to an understudied group of metalloproteases of the M36 class of fungalysins unique to fungi. They are generally synthesized as propeptides with fairly long prodomains and highly conserved regions within their catalytic core. Through structure-function analysis of Mpr1, our study identified the prodomain cleavage sites of Mpr1 and demonstrated that when mutated, the prodomain appears to remain attached to the catalytic C-terminus of Mpr1 rendering a nonfunctional Mpr1 protein and an inability for cryptococci to cross the BBB. We found that proteolytic activity of Mpr1 was dependent on the coordination of zinc with two histidine residues in the active site of Mpr1, since amino acid substitutions in the HExxH motif abolished Mpr1 proteolytic activity and prevented the migration of cryptococci across the BBB. A phylogenetic analysis of Mpr1 revealed a distinct pattern likely reflecting the neurotropic nature of C. neoformans and the specific function of Mpr1 in breaching the BBB. This study contributes to a deeper understanding of the molecular regulation of Mpr1 activity and may lead to the development of specific inhibitors that could be used to restrict fungal penetration of the CNS and thus prevent cryptococcal meningoencephalitis-related deaths.

Invasion of the central nervous system by Cryptococcus neoformans requires a secreted fungal metalloprotease.

UNLABELLED: Cryptococcus spp. cause life-threatening fungal infection of the central nervous system (CNS), predominantly in patients with a compromised immune system. Why Cryptococcus neoformans has this remarkable tropism for the CNS is not clear. Recent research on cerebral pathogenesis of C. neoformans revealed a predominantly transcellular migration of cryptococci across the brain endothelium; however, the identities of key fungal virulence factors that function specifically to invade the CNS remain unresolved. Here we found that a novel, secreted metalloprotease (Mpr1) that we identified in the extracellular proteome of C. neoformans (CnMpr1) is required for establishing fungal disease in the CNS. Mpr1 belongs to a poorly characterized M36 class of fungalysins that are expressed in only some fungal species. A strain of C. neoformans lacking the gene encoding Mpr1 (mpr1Δ) failed to breach the endothelium in an in vitro model of the human blood-brain barrier (BBB). A mammalian host infected with the mpr1Δ null strain demonstrated significant improvement in survival due to a reduced brain fungal burden and lacked the brain pathology commonly associated with cryptococcal disease. The in vivo studies further indicate that Mpr1 is not required for fungal dissemination and Mpr1 likely targets the brain endothelium specifically. Remarkably, the sole expression of CnMPR1 in Saccharomyces cerevisiae resulted in a robust migration of yeast cells across the brain endothelium, demonstrating Mpr1's specific activity in breaching the BBB and suggesting that Mpr1 may function independently of the hyaluronic acid-CD44 pathway. This distinct role for Mpr1 may develop into innovative treatment options and facilitate a brain-specific drug delivery platform. IMPORTANCE: Cryptococcus neoformans is a medically relevant fungal pathogen causing significant morbidity and mortality, particularly in immunocompromised individuals. An intriguing feature is its strong neurotropism, and consequently the hallmark of cryptococcal disease is a brain infection, cryptococcal meningoencephalitis. For C. neoformans to penetrate the central nervous system (CNS), it first breaches the blood-brain barrier via a transcellular pathway; however, the identities of fungal factors required for this transmigration remain largely unknown. In an effort to identify extracellular fungal proteins that could mediate interactions with the brain endothelium, we undertook a proteomic analysis of the extracellular proteome and identified a secreted metalloprotease (Mpr1) belonging to the M36 class of fungalysins. Here we found that Mpr1 promotes migration of C. neoformans across the brain endothelium and into the CNS by facilitating attachment of cryptococci to the endothelium surface, thus underscoring the critical role of M36 proteases in fungal pathogenesis.

Staphylococcal cassette chromosome mec (SCCmec) typing of methicillin-resistant Staphylococcus aureus strains isolated in 11 Asian countries: a proposal for a new nomenclature for SCCmec elements.

A description of staphylococcal cassette chromosome mec (SCCmec) elements carried by 615 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated in 11 Asian countries is reported, and a novel nomenclatural system based on their structures is proposed. The 615 strains were classified as type 3A (370 strains), type 2A (207 strains), type 2B (32 strains), type 1B (1 strain), and nontypeable (5 strains). The previously reported type III SCCmec (DDBJ/EMBL/GenBank accession no. AB037671) carried by the MRSA strain 85/2082 was ascertained to be composed of two SCC elements, type 3A SCCmec and SCCmercury. PCR analysis indicated that 310 of 370 type 3A SCCmec strains carried both SCC elements. These strains were prevalent in eight countries: Thailand, Sri Lanka, Indonesia, Vietnam, Philippines, Saudi Arabia, India, and Singapore. The remaining 60 type 3A SCCmec strains differed with respect to the left extremity polymorphism or to the presence of ccrC. Among these, two were identified as carrying only type 3A SCCmec elements, but their left extremities differed. Type 2A SCCmec strains predominated in Korea and Japan, although the frequency of the presence of ant(4')-1 gene downstream of mecA varied (53% for Korean strains; 93% for Japanese strains). Various SCCmec elements were identified in the tested strains, and limited numbers were identified by their multilocus sequence typing genotypes. These data suggest that numerous MRSA clones are disseminated in Asian hospitals, and these consist of minor clones that are presumed to have arisen locally and major clones that are presumed to have been introduced from other countries.

A novel methicillin-resistance cassette in community-acquired methicillin-resistant Staphylococcus aureus isolates of diverse genetic backgrounds.

Until recently, it has been unclear whether community-acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) isolates represent the spread of hospital MRSA isolates into the community. In 2 CA-MRSA isolates, a novel genetic element, designated staphylococcal cassette chromosome mec (SCCmec) type IV, was found; it differs from SCCmec types I-III in its small size and absence of non-beta-lactam genetic-resistance determinants. To study the prevalence of type IV SCCmec, polymerase chain reaction characterization of SCCmec was performed on DNA from 12 CA-MRSA isolates. The 12 CA-MRSA isolates were from diverse genetic backgrounds, as evidenced by their stratification into 5 pulsed-field gel electrophoresis types, 4 coagulase types, and 2 ribotypes. Eleven of the 12 isolates contained the novel SCCmec type IV element. Ten were resistant only to beta-lactam antibiotics. SCCmec type IV is present on the genome of CA-MRSA isolates. Its relatively small size and presence in isolates of diverse genetic backgrounds suggest that it may spread among S. aureus isolates.

Novel type of staphylococcal cassette chromosome mec identified in community-acquired methicillin-resistant Staphylococcus aureus strains.

We identified a new type of staphylococcal cassette chromosome mec (SCCmec) from two community-acquired methicillin-resistant Staphylococcus aureus (MRSA) strains. The novel element, designated type IV SCCmec, had a unique combination of the class B mec gene complex and the type 2 ccr gene complex and was much smaller in size (21 to 24 kb) than previously identified SCCmec elements of hospital-acquired MRSA. Consistent with the strains' susceptibilities to various non-beta-lactam antibiotics, the type IV SCCmec was devoid of any antibiotic resistance genes other than the mecA gene.