Histomonas Research Articles

Evaluation of an attenuated chicken-origin Histomonas meleagridis vaccine for the prevention of histomonosis in chickens

IntroductionHistomonosis, a protozoan disease caused by Histomonas meleagridis, poses a significant economic burden on domestic poultry in China. To reduce the losses caused by this disease in chickens, an attenuated vaccine was developed by exploiting the diminished virulence of H. meleagridis through successive in vitro passages.MethodsFour experiments were conducted to evaluate the viability of attenuated H. meleagridis as a potential vaccine candidate. Experiment 1 evaluated the route of infection (oral vs. intracloacal) and dose (5 × 104, 1 × 105, and 2 × 105H. meleagridis/chicken) using the virulent strain H. meleagridis JSYZ-D10. Experiment 2 evaluated the attenuated effect of the H. meleagridis JSYZ-D168 strain (infection dose: 2 × 105H. meleagridis/chicken). Experiment 3 evaluated the immunoprotective effect of different immunization doses (5 × 104, 1 × 105, and 2 × 105H. meleagridis/chicken). Experiment 4 evaluated the immunoprotective effect of different immunization schedules (immunization at 3 days of age; immunization at 14 days of age; two immunizations, one at 3 days of age and one at 14 days of age; immunization and infection dose: 2 × 105H. meleagridis/chicken).ResultsThe results showed that the intracloacal route of infection was more effective and stable compared to the oral route. The pathogenicity of the JSYZ-D168 H. meleagridis strain was significantly reduced compared to the original virulent strain. Chickens vaccinated by intracloacal immunization at a dose of 2 × 105H. meleagridis/chicken on day 14 provided effective protection against a virulent strain challenge, significantly resulting in increased body weight and reduced lesions in the cecum and liver within 28 days post-immunization (p < 0.05). Poor immunoprotection was obtained either when the immunization dose was 1 × 105H. meleagridis/chicken or when the immunization program was a single immunization at 3 days of age only.DiscussionIn conclusion, the administration of a vaccine provides a measurable degree of protection against the detrimental effects induced by H. meleagridis, thus warranting its endorsement in clinical settings.

Metabolic Profile of Histomonas meleagridis in Dwyer’s Media with and Without Rice Starch

Metabolic Profile of Histomonas meleagridis in Dwyer’s Media with and Without Rice Starch

Trichomonad Disease in Wild Turkeys (Meleagris gallopavo): Pathology and Molecular Characterization of Histomonas, Tetratrichomonas, Tritrichomonas, and Simplicimonas spp.

The Wild Turkey (Meleagris gallopavo) is a geographically widespread, popular game bird and conservation icon in North America. Following successful reestablishment in parts of the US and Canada, regional declines have fueled population health concerns; therefore, understanding mortality causes and spatiotemporal patterns of disease is important to uncover potential ongoing and future health risks. Histomonosis, caused by the trichomonad Histomonas meleagridis, is a well-established and potentially fatal disease in Wild Turkeys; however, its prevalence and potential population health impacts remain poorly understood. Moreover, molecular tools recently have allowed for the detection of additional trichomonads that similarly can cause fatal disease in Wild Turkeys. We describe and compare disease due to H. meleagridis with that of Tetratrichomonas gallinarum, Tritrichomonas sp., and Simplicimonas sp. in Wild Turkeys in the southeastern US. Among 857 Wild Turkeys evaluated postmortem from 2002 to 2023, 34 (4.0%) were diagnosed with trichomonad disease, often assumed to be histomonosis prior to molecular testing. However, among 25 debilitating to fatal trichomonad disease cases for which etiologies were confirmed by PCR from 2015 to 2023, H. meleagridis was detected in 16/25 (64.0%), T. gallinarum in 6/25 (24.0%), Tritrichomonas sp. in 2/25 (8.0%) and Simplicimonas sp. in 1/25 (4.0%). These turkeys had similar clinical manifestations, and although lesion patterns varied to some extent, liver and/or intestinal tract was most commonly affected. Coinfections were common among all turkeys with trichomonad disease from 2015 to 2023 (21/25, 84.0%) and included viruses (lymphoproliferative disease virus, avian poxvirus), bacteria (Streptococcus gallolyticus, Listeria monocytogenes, Escherichia coli), and other protozoa (Sarcocystis sp., Haemoproteus sp.). Our results highlight the importance of molecular diagnostic testing in determining etiologies of trichomonad disease in Wild Turkeys. Further evaluation of the epidemiology and pathogenesis of trichomonad disease and its varied etiologies in Wild Turkeys and other birds is warranted to better understand risk factors and potential health impacts.

Molecular detection and characterization of Histomonas meleagridis in fighting cocks Thailand

Molecular detection and characterization of Histomonas meleagridis in fighting cocks Thailand

Hepatic transcriptomic analysis reveals differential regulation of metabolic and immune pathways in three strains of chickens with distinct growth rates exposed to mixed parasite infections.

During parasite infections, the liver may prioritise immune-related pathways over its metabolic functions. Intestinal infections caused by Ascaridia galli and Heterakis gallinarum impair feed intake, nutrient absorption, and weight gain. Histomonas meleagridis, vectored by H. gallinarum, can also damage liver tissues, potentially impairing liver functions. This study examined the hepatic gene expression in three strains of chickens: Ross-308 (R), Lohmann Brown Plus (LB), and Lohmann Dual (LD), 2weeks after an experimental infection (n = 18) with both A. galli and H. gallinarum or kept as uninfected control (n = 12). Furthermore, H. gallinarum infection led to a co-infection with H. meleagridis. The mixed infections reduced feed intake and the average daily weight gain (P < 0.001). The infections also increased the plasma concentrations of alpha (1)-acid glycoprotein and the antibody titre against H. meleagridis (P = 0.049), with no strain differences (P > 0.05). For host molecular response, 1887 genes were differentially expressed in LD, while 275 and 25 genes were differentially expressed in R and LB, respectively. The up-regulated genes in R and LD were mostly related to inflammatory and adaptive immune responses, while down-regulated genes in LD were involved in metabolic pathways, including gluconeogenesis. Despite performance differences among the strains, worm burdens were similar, but hepatic molecular responses differed significantly. Moreover, there was an indication of a shift in hepatic functions towards immune-related pathways. We, therefore, conclude that the liver shifts its functions from metabolic to immune-related activities in chickens when challenged with mixed parasite species.

HISTOMONAS MELEAGRIDIS INFECTIONS IN TURKEYS IN THE USA: A CENTURY OF PROGRESS, RESURGENCE, AND TRIBUTE TO ITS EARLY INVESTIGATORS, THEOBALD SMITH, ERNST TYZZER, AND EVERETT LUND.

Histomoniasis, caused by the protozoan, Histomonas meleagridis, is an economically important disease of turkeys, and it also affects several other species of domesticated and wild Galliformes, including chickens. Under natural conditions, the parasite is transmitted through eggs of a nematode, Heterakis gallinarum, that shares its hosts with Hi. meleagridis. The protozoan infects tissues of both male and female He. gallinarum and eventually is carried within the worm egg. Histomonas meleagridis more readily infects and develops in chickens, and the proximity of chicken farms is a major risk factor for outbreaks in turkeys. Chemoprophylaxis had controlled Hi. meleagridis in turkeys very successfully, but histomoniasis has recently reemerged in turkeys because anti-histomonal drugs are no longer permitted by the United States Food and Drug Administration because of the concerns for residual toxins in poultry meat. Horizontal transmission of the protozoan in the absence of worm eggs remains a mystery because the flagellate trophozoite excreted in the feces of turkeys is not viable for any length of time. A proposed resistant stage of the protozoan has not yet been conclusively demonstrated. Here we review the discovery of the protozoan and the current status of the disease and its control.

The Relative Frequency of Histomonas meleagridis Infection in Turkey Flocks in Some Provinces of Iran

Background: Histomoniasis is caused by the protozoan Histomonas meleagridis with an intermediate host of Heterakis gallinarum, which results in ulceration of the ceca walls, enlargement of the ceca by large casts, mesenteric inflammation, and liver necrosis. This disease is very important in Iran’s growing turkey breeding industry. Objectives: The present study aims to evaluate the relative frequency of H. meleagridis infection in different turkey flocks to draw a cross-sectional picture of H. meleagridis infection in Golestan, Mazandaran, Guilan, and Tehran provinces of Iran. Methods: This study is a cross-sectional survey of H. meleagridis infection during spring. Dropping samples were taken from backyard and commercial turkey flocks. After taking the fecal samples, they were investigated by Giemsa staining under a light microscope. A PCR test was performed to confirm the diagnosis of infection. Results: Out of 240 samples (from 19 flocks), 20 infected samples were detected by direct microscopic observation of H. meleagridis, and PCR confirmed 15 samples. Conclusion: The results of this study showed that the relative frequency of H. meleagridis infection was lower than in similar studies in other parts of the world. This finding may be due to Iran’s less widespread use of turkey production. Considering the growth of the turkey production industry in Iran over the last decade and its further production over the next few years, it is necessary to evaluate histomoniasis.

MicroRNA expression profile of chicken liver at different times after Histomonas meleagridis infection

Histomonas meleagridis, an anaerobic intercellular parasite, is known to infect gallinaceous birds, particularly turkeys and chickens. The resurgence of histomonosis in recent times has resulted in significant financial setbacks due to the prohibition of drugs used for disease treatment. Currently, research on about H. meleagridis primarily concentrate on the examination of its virulence, gene expression analysis, and the innate immunity response of the host organism. However, there is a lack of research on differentially expressed miRNAs (DEMs) related to liver infection induced by H. meleagridis. In this study, the weight gain and pathological changes at various post-infection time points were evaluated through animal experiments to determine the peak and early stages of infection. Next, High-throughput sequencing was used to examine the expression profile of liver miRNA at 10 and 15 days post-infection (DPI) in chickens infected with the Chinese JSYZ-F strain of H. meleagridis. A comparison with uninfected controls revealed the presence of 120 and 118 DEMs in the liver of infected chickens at 10 DPI and 15 DPI, respectively, with 74 DEMs being shared between the two time points. Differentially expressed microRNAs (DEMs) were categorized into three groups based on the time post-infection. The first group (L1) includes 45 miRNAs that were differentially expressed only at 10 DPI and were predicted to target 1646 genes. The second group (L2) includes 43 miRNAs that were differentially expressed only at 15 DPI and were predicted to target 2257 genes. The third group (L3) includes 75 miRNAs that were differentially expressed at both 10 DPI and 15 DPI and were predicted to target 1623 genes. At L1, L2, and L3, there were 89, 87, and 41 significantly enriched Gene Ontology (GO) terms, respectively (p<0.05). The analysis of differentially expressed miRNA target genes using KEGG pathways revealed significant enrichment at L1, L2, and L3, with 3, 4, and 5 pathways identified, respectively (p<0.05). This article suggests that the expression of liver miRNA undergoes dynamic alterations due to H. meleagridis and the host. It showed that the expression pattern of L1 class DEMs was more conducive to regulating the development of the inflammatory response, while the L2 class DEMs were more conducive to augmenting the inflammatory response. The observed patterns of miRNA expression associated with inflammation were in line with the liver's inflammatory process following infection. The results of this study provide a basis for conducting a comprehensive analysis of the pathogenic mechanism of H. meleagridis from the perspective of host miRNAs.

Concurrent Histomonas meleagridis and Hemorrhagic Enteritis Virus Infection in a Turkey Flock with Recurrent History of Blackhead Disease.

Intestinal health is one of the key factors required for the growth and production of turkeys. Histomoniasis (blackhead disease), caused by a protozoan parasite, Histomonas meleagridis, is a reemerging threat to the turkey industry. Increased incidences of histomoniasis have been reported in recent years due to withdrawal of antihistomonas treatments. H. meleagridis affects ceca and causes cecal inflammation and necrosis. H. meleagridis migrates from ceca to the liver and causes liver necrosis, resulting in high mortalities. Ironically, field outbreaks of histomoniasis are not always associated with high mortalities, while low mortalities have also been documented. There are several exacerbating factors associated with high mortality rates in histomoniasis outbreaks, with concurrent infection being one of them. Recurrent histomoniasis outbreaks in a newly constructed barn were documented, and concurrent infection of H. meleagridis and hemorrhagic enteritis virus was confirmed. Currently, neither commercial vaccines nor prophylactic or therapeutic solutions are available to combat histomoniasis. However, there are treatments, vaccines, and solutions to minimize or prevent concurrent infections in turkeys. In addition to implementing biosecurity measures, measures to prevent concurrent infections are critical steps that the turkey industry can follow to reduce mortality rates and minimize the production and economic losses associated with histomoniasis outbreaks.

Tissue cytokines in chickens from lines selected for high or low humoral antibody responses, given supplemental Limosilactobacillus reuteri and challenged with Histomonas meleagridis.

Histomonas meleagridis, a protozoan parasite, induces blackhead disease (histomoniasis) in poultry. During hatching, chicks from lines divergently selected for high (HAS) and low (LAS) antibody responses to sheep red blood cells were divided into two groups, each of HAS and LAS, and placed in pens with wood shavings as litter. Feed and water were allowed ad libitum. Half of the chicks from each line had Limosilactobacillus reuteri (L. reuteri) inoculated to their drinking water. On day 18, all chicks were given a transcloacal inoculation of 100,000 H. meleagridis cells. Then, 10days later, they were euthanized, followed by collection of tissues from the brain, cecal tonsil, ceca, liver, thymus, and spleen for qPCR analyses of cytokines involved in immunological development. Changes in cytokine expressions were most numerous in the cecal tonsil, ceca, and liver. In the absence of a functional medication for control of histomoniasis, L. reuteri and/or its secretory product, reuterin, might serve, in some genetic populations, as a means to reduce the impact of histomoniasis in chickens. The data demonstrate that L. reuteri treatment had tissue specificity between the two genetic lines, in which the effects were targeted primarily toward the cecal tonsil, ceca, and liver, which are the primary tissue targets of the parasite (H. meleagridis), as well as the thymus and spleen. However, interactions among main effects reflect that responses to inflammatory markers observed in tissues for one genetic line may not be observed in another.

Prevalence of parasites in selected captive bird species.

Blood and fecal samples of chukar partridge (Alectoris chukar), albino pheasant (Phasianus colchicus), silver pheasant (Lophura nycthemera), rose-ringed parakeet (Psittacula krameri) and turkeys (Meleagris gallopavo) were analyzed to check parasitic prevalence. To record parasites these five avian species were placed kept in separate cages at Avian Conservation and Research Center, Department of Wildlife an Ecology, University of Veterinary and Animal Sciences, Lahore, Pakistan. 100 fecal and 100 blood samples for each bird species were inspected to analyze internal parasites. During present study, 17 species of endoparasites 14 from fecal samples and three from blood were examined. Two species of ectoparasites i.e. mite Dermanyssus gallinae 42% and fowl ticks Args persicus 41%were studied. Blood parasites included Plasmodium juxtanucleare 50%, Leucoctoyzoon simond having parasitic prevalence 40%, and Aegyptinella pullorum having parasitic prevalence of 40%. Parasitic species recorded from fecal samples included 6 species of nematodes viz. Allodpa suctoria 2%. Syngamus trachea with parasitic prevalence of 60%, Capillaria annulata 37.5%, Ascardia galli 24%, Capillaria anatis 40% and Heterakis gallinarum 28.3%. Similarly, two species of trematodes viz. Prosthogonimus ovatus having parasitic prevalence of 50% and Prosthogonimus macrorchis 21% were also documented from fecal avian samples . Single cestode species Raillietina echinobothrida having parasitic prevalence of 72% and 3 protozoan species i.e. Eimeria maxima having parasitic prevalence of 21%, Giardia lamblia 41% and Histomonas meleagridis 18% were documented during corpological analysis. In our recommendation, proper sanitation, medication and vaccination of bird's enclousres are suggested to avoid parasites.

Identification of small circular DNA viruses in coyote fecal samples from Arizona (USA).

Coyotes (Canis latrans) have a broad geographic distribution across North and Central America. Despite their widespread presence in urban environments in the USA, there is limited information regarding viruses associated with coyotes in the USA and in particular the state of Arizona. To explore viruses associated with coyotes, particularly small DNA viruses, 44 scat samples were collected (April-June 2021 and November 2021-January 2022) along the Salt River near Phoenix, Arizona (USA), along 43 transects (500m). From these samples, we identified 11 viral genomes: two novel circoviruses, six unclassified cressdnaviruses, and two anelloviruses. One of the circoviruses is most closely related to a circovirus sequence identified from an aerosolized dust sample in Arizona, USA. The second circovirus is most closely related to a rodent-associated circovirus and canine circovirus. Of the unclassified cressdnaviruses, three encode replication-associated proteins that are similar to those found in protists (Histomonas meleagridis and Monocercomonoides exilis), implying an evolutionary relationship with or a connection to similar unidentified protist hosts. The two anelloviruses are most closely related to those found in rodents, and this suggests a diet-related identification.

Early Detection of Histomoniasis in Blood Samples by PCR and Sequencing.

Histomoniasis is a deadly disease of turkeys causing devastating economic losses to the poultry industry. In field outbreaks, a presumptive diagnosis is made based on gross pathology lesions and confirmed by histopathology. An early detection tool with quick turnaround time is needed to prevent the spread of histomoniasis. With this objective, two studies were conducted in turkeys. In Study 1, 40 poults were housed in two pens (20 poults/pen) and challenged at 14 days of age with Histomonas meleagridis by intracloacal route. Blood samples were collected 4 days postchallenge. Fifty-five percent (22/40) of the blood samples tested positive for H. meleagridis based on PCR using primers targeted against the 18S rRNA gene and confirmed by sequencing. In Study 2, 40 poults were housed in two groups and raised in floor pens. Groups 1 and 2 served as negative and challenge controls, respectively. At 14 days of age, the birds in Group 2 were challenged with H. meleagridis by intracloacal route. Blood samples were collected 2 days postchallenge. Five percent (1/20) of the blood samples tested positive for H. meleagridis, based on PCR and confirmed by sequencing. The results from both studies indicate that H. meleagridis DNA can be detected in the blood samples by PCR and confirmed by sequencing as early as 4 days postchallenge. This early detection method could be applied in field outbreaks to detect and confirm histomoniasis as early as possible.

1H-NMR based-metabolomics reveals alterations in the metabolite profiles of chickens infected with ascarids and concurrent histomonosis infection

BackgroundGut infections of chickens caused by Ascaridia galli and Heterakis gallinarum are associated with impaired host performance, particularly in high-performing genotypes. Heterakis gallinarum is also a vector of Histomonas meleagridis that is often co-involved with ascarid infections. Here, we provide a first insight into the alteration of the chicken plasma and liver metabolome as a result of gastrointestinal nematode infections with concomitant histomonosis. 1H nuclear magnetic resonance (1H-NMR) based-metabolomics coupled with a bioinformatics analysis was applied to explore the variation in the metabolite profiles of the liver (N = 105) and plasma samples from chickens (N = 108) experimentally infected with A. galli and H. gallinarum (+H. meleagridis). This was compared with uninfected chickens at different weeks post-infection (wpi 2, 4, 6, 10, 14, 18) representing different developmental stages of the worms.ResultsA total of 31 and 54 metabolites were quantified in plasma and aqueous liver extracts, respectively. Statistical analysis showed no significant differences (P > 0.05) in any of the 54 identified liver metabolites between infected and uninfected hens. In contrast, 20 plasma metabolites including, amino acids, sugars, and organic acids showed significantly elevated concentrations in the infected hens (P < 0.05). Alterations of plasma metabolites occurred particularly in wpi 2, 6 and 10, covering the pre-patent period of worm infections. Plasma metabolites with the highest variation at these time points included glutamate, succinate, trimethylamine-N-oxide, myo-inositol, and acetate. Differential pathway analysis suggested that infection induced changes in (1) phenylalanine, tyrosine, and tryptophan metabolism, (2) alanine, aspartate and glutamate metabolism; and 3) arginine and proline metabolism (Pathway impact > 0.1 with FDR adjusted P-value < 0.05).ConclusionIn conclusion, 1H-NMR based-metabolomics revealed significant alterations in the plasma metabolome of high performing chickens infected with gut pathogens—A. galli and H. gallinarum. The alterations suggested upregulation of key metabolic pathways mainly during the patency of infections. This approach extends our understanding of host interactions with gastrointestinal nematodes at the metabolic level.

Macromorphological Changes after Spontaneous Co-invasion of Eimeriosis, Histomonosis, and Trichomoniasis in Domestic Chickens

The study of macro morphological changes is important for recognizing pathological processes and diagnosing diseases, especially co-invasions. The current study aimed to reveal macro morphological changes during spontaneous co-invasion of Eimeria spp., Histomonas meleagridis, and Trichomonas gallinae in adult chickens. The methods of evisceration and parasitological studies of the carcasses of adult domestic chickens (n = 31) aged 1.5-2.3 years, and (n = 8) are the control group, died of a natural death from farms in the Kharkiv region of Ukraine revealed the peculiarities of manifestations of macro morphological changes in organs, which were characterized by manifestations of pathologies in 100% of cases in dead chickens by changes in the intestines and liver, in 48.39% in the spleen, in 16.13% in the bursa of Fabricius, in 16.13% in the peritoneum and 9.68% in skin. In particular, a mucosal-hemorrhagic inflammatory process was observed in the intestines of chickens with damage to both thin and thick parts (duodeno-jejuno-ileo-typho-cloacitis). This inflammatory process was observed in combination with necrotic-granulomatous lesions on the intestinal wall. A combined lesion of the liver was detected - hepatomegaly on the background of steatosis, multifocal necrosis, and granulomas (shiny, vitreous, with a white center) in the presence of Histomonas meleagridis and Trichomonas gallinae. A granulomatous splenitis was diagnosed in the spleen of chickens. Necrotic-granulomatous lesions leading to cyst formation were identified in the bursa of Fabricius. Additionally, granulomatous lesions originating from trichomoniasis were observed on the peritoneum and skin. These findings highlight the systemic nature of pathological-anatomical changes resulting from the co-infection of eimeriosis, histomoniasis, and trichomoniasis in domestic chickens. This systemic manifestation signifies the occurrence of multi-organ failure and holds valuable diagnostic implications.

Antimicrobial Peptides (AMP) in the Cell-Free Culture Media of Xenorhabdus budapestensis and X. szentirmaii Exert Anti-Protist Activity against Eukaryotic Vertebrate Pathogens including Histomonas meleagridis and Leishmania donovani Species.

Anti-microbial peptides provide a powerful toolkit for combating multidrug resistance. Combating eukaryotic pathogens is complicated because the intracellular drug targets in the eukaryotic pathogen are frequently homologs of cellular structures of vital importance in the host organism. The entomopathogenic bacteria (EPB), symbionts of entomopathogenic-nematode species, release a series of non-ribosomal templated anti-microbial peptides. Some may be potential drug candidates. The ability of an entomopathogenic-nematode/entomopathogenic bacterium symbiotic complex to survive in a given polyxenic milieu is a coevolutionary product. This explains that those gene complexes that are responsible for the biosynthesis of different non-ribosomal templated anti-microbial protective peptides (including those that are potently capable of inactivating the protist mammalian pathogen Leishmania donovanii and the gallinaceous bird pathogen Histomonas meleagridis) are co-regulated. Our approach is based on comparative anti-microbial bioassays of the culture media of the wild-type and regulatory mutant strains. We concluded that Xenorhabdus budapestensis and X. szentirmaii are excellent sources of non-ribosomal templated anti-microbial peptides that are efficient antagonists of the mentioned pathogens. Data on selective cytotoxicity of different cell-free culture media encourage us to forecast that the recently discovered "easy-PACId" research strategy is suitable for constructing entomopathogenic-bacterium (EPB) strains producing and releasing single, harmless, non-ribosomal templated anti-microbial peptides with considerable drug, (probiotic)-candidate potential.

NlpC/P60 peptidoglycan hydrolases of Trichomonas vaginalis have complementary activities that empower the protozoan to control host-protective lactobacilli.

Trichomonas vaginalis is a human protozoan parasite that causes trichomoniasis, a prevalent sexually transmitted infection. Trichomoniasis is accompanied by a shift to a dysbiotic vaginal microbiome that is depleted of lactobacilli. Studies on co-cultures have shown that vaginal bacteria in eubiosis (e.g. Lactobacillus gasseri) have antagonistic effects on T. vaginalis pathogenesis, suggesting that the parasite might benefit from shaping the microbiome to dysbiosis (e.g. Gardnerella vaginalis among other anaerobes). We have recently shown that T. vaginalis has acquired NlpC/P60 genes from bacteria, expanding them to a repertoire of nine TvNlpC genes in two distinct clans, and that TvNlpCs of clan A are active against bacterial peptidoglycan. Here, we expand this characterization to TvNlpCs of clan B. In this study, we show that the clan organisation of NlpC/P60 genes is a feature of other species of Trichomonas, and that Histomonas meleagridis has sequences related to one clan. We characterized the 3D structure of TvNlpC_B3 alone and with the inhibitor E64 bound, probing the active site of these enzymes for the first time. Lastly, we demonstrated that TvNlpC_B3 and TvNlpC_B5 have complementary activities with the previously described TvNlpCs of clan A and that exogenous expression of these enzymes empower this mucosal parasite to take over populations of vaginal lactobacilli in mixed cultures. TvNlpC_B3 helps control populations of L. gasseri, but not of G. vaginalis, which action is partially inhibited by E64. This study is one of the first to show how enzymes produced by a mucosal protozoan parasite may contribute to a shift on the status of a microbiome, helping explain the link between trichomoniasis and vaginal dysbiosis. Further understanding of this process might have significant implications for treatments in the future.

Mapping the poultry insectome in and around broiler breeder pullet farms identifies new potential Dipteran vectors of Histomonas meleagridis

BackgroundHistomonas meleagridis can infect chickens and turkeys. It uses the eggs of the cecal worm Heterakis gallinarum as a vector and reservoir. Litter beetles (Alphitobius diaperinus) and other arthropod species have been implicated as potential vectors, but little information about other arthropod species as potential vectors is known.MethodsFour broiler breeder pullet farms were sampled every 4 months. On each farm, three types of traps were set inside and outside two houses. Trapped arthropod specimens were morphologically identified at order level and grouped into families/types when possible. Selected specimens from abundant types found both inside and outside barns were screened for H. meleagridis and H. gallinarum by qPCR.ResultsA total of 4743 arthropod specimens were trapped. The three most frequently encountered orders were Diptera (38%), Coleoptera (17%), and Hymenoptera (7%). Three hundred seventeen discrete types were differentiated. More arthropods were trapped outside than inside. Alpha diversity was greater outside than inside but not significantly influenced by season. The composition of the arthropod populations, including the insectome, varied significantly between trap location and seasons. Up to 50% of litter beetles tested positive for H. meleagridis DNA 4 months after an observed histomonosis outbreak. Sporadically litter beetles were positive for H. gallinarum DNA. Thirteen further arthropod types were tested, and specimens of four Dipteran families tested positive for either one or both parasites.ConclusionsThis study describes the insectome in and around broiler breeder pullet farms and identifies new potential vectors of H. meleagridis through qPCR. The results show a limited but present potential of arthropods, especially flies, to transmit histomonosis between farms.Graphical

Identification and Characterization of α-Actinin 1 of Histomonas meleagridis and Its Potential Vaccine Candidates against Histomonosis.

Histomonas meleagridis is a protozoan parasite that causes histomonosis in gallinaceous birds such as turkeys and chickens. Since the banning and restricted usage of effective drugs such as nitarsone, 80-100% morbidity and mortality occur in turkeys and 20-30% mortality in chickens. New ideas are needed to resolve the re-emergence of histomonosis in poultry. In this study, the α-actinin encoding gene from H. meleagridis was cloned. The 1839-bp gene encoding 612 amnio acids showed close phylogenetic relationships with Trichomonas vaginalis and Tritrichomonas foetus. It was then inserted into the prokaryotic expression vector pET28a(+) and induced with isopropyl-β-D-thiogalactopyranoside. A 73 kDa recombinant protein rHmα-actinin 1 was obtained and purified with a Ni-NTA chromatography column. rHmα-actinin 1 was recognized by mouse anti-rHmα-actinin 1 polyclonal antibody, mouse anti-rHmα-actinin 1 monoclonal antibody, and rehabilitation sera from H. meleagridis infected chickens. Native α-actinin 1 in the total proteins of H. meleagridis can also be detected with mouse anti-rHmα-actinin monoclonal antibody. Immunolocalization assays showed that Hmα-actinin 1 was mainly distributed in the cytoplasm of virulent histomonads JSYZ-D9 and in the peripheral regions (near the plasma membrane) of attenuated histomonads JSYZ-D195. Based on in vivo experiment, when chickens were subcutaneously immunized with rHmα-actinin 1 at 5 and 12 days old and then challenged with H. meleagridis at 19 days old, rHmα-actinin 1 reduced the lesion scores 12 days after infection (31 days old) and increased the body weight gain during the challenged period (19-31 days old). Furthermore, it also strengthened the cellular and humoral immune responses 7 days after the second immunization (19 days old). In conclusion, Hmα-actinin 1 could be used as a candidate antigen to develop vaccines against chicken histomonosis.

Molecular Prevalence of Three Chicken Gastrointestinal Tract Pathogens and Phylogenetic Characterization of Tetratrichomonas gallinarum in Türkiye

Several species of parasites infect chickens and can cause economic losses. Histomonas meleagridis, its intermediate host Heterakis gallinarum, and Tetratrichomonas gallinarum are the most common parasites of poultry. The current study aimed to determine the molecular prevalence and phylogenetic relationships of H. meleagridis, He. gallinarum, and T. gallinarum in chickens in Central Anatolia Region of Türkiye. For this, a total of 100 fecal specimens from chickens were analyzed by using a PCR assay targeting the 18S rRNA gene region of H. meleagridis and T. gallinarum and the mtDNA COI gene region of He. gallinarum. PCR analysis identified T. gallinarum in 11 (1.1%) specimens, whereas other species were not found in all the examined specimens. Positive specimens were detected only in backyard chickens. Sequence analyses identified two novel genotypes named TRTgal1 and TRTgal3, and one known genotype (TRTgal2) of T. gallinarum. The TRTgal2 genotype was found to be identical to the human genotype (AY247746) and the four avian genotypes. Phylogenetic analyses of the obtained genotypes clustered in separate monophyletic clades. Our study provides the first data on T. gallinarum in chickens in Türkiye and contributes to public health with the identified zoonotic genotype and knowledge of the epidemiology of this parasite.