In Vivo Characterization of the Anti-Glutathione S-Transferase Antibody Using an In Vitro Mite Feeding Model

Poultry red mites (Dermanyssus gallinae, PRMs), tropical fowl mites (Ornithonyssus bursa, TFMs), and northern fowl mites (O. sylviarum, NFMs) are blood-feeding pests that debilitate poultry worldwide. Glutathione S-transferase (GST) plays an important role in the detoxification and drug metabolism of mites. However, research on avian mite GSTs as vaccine antigens is still lacking. Therefore, we aimed to evaluate the potential of avian mite GSTs for vaccine development. We identified GST genes from TFMs and NFMs. We prepared recombinant GST (rGST) from TFMs, NFMs, and PRMs, and assessed their protein functions. Moreover, we evaluated the cross-reactivity and acaricidal effect of immune plasma against each rGST on TFMs, NFMs, and PRMs. The deduced amino acid sequences of GSTs from TFMs and NFMs were 80% similar to those of the PRMs. The rGSTs exhibited catalytic activity in conjugating glutathione to the 1-chloro-2,4-dinitrobenzene substrate. Immune plasma against each rGST showed cross-reactivity with rGST from different mite species. Moreover, the survival rate of PRMs fed with immune plasma against the rGST of TFMs and NFMs was significantly lower than that of the control plasma. These results demonstrate the potential application of GST as an antigen for the development of a broad-spectrum vaccine against avian mites.

Potential of ferritin 2 as an antigen for the development of a universal vaccine for avian mites, poultry red mites, tropical fowl mites, and northern fowl mites

Introduction

Poultry red mites (PRMs, Dermanyssus gallinae), blood-sucking ectoparasites, are a threat to the poultry industry because of reduced production caused by infestation. In addition, tropical fowl mites (TFMs, Ornithonyssus bursa) and northern fowl mites (NFMs, Ornithonyssus sylviarum) are hematophagous, distributed in various regions, genetically and morphologically close to PRMs, and cause similar problems to the poultry industry. Vaccine approaches have been studied for PRM control, and several molecules have been identified in PRMs as candidates for effective vaccine antigens. The development of an anti-PRM vaccine as a universal vaccine with broad efficacy against avian mites could improve the productivity of poultry farms worldwide. Molecules that are highly conserved among avian mites and have critical functions in the physiology and growth of mites could be ideal antigen candidates for the development of universal vaccines. Ferritin 2 (FER2), an iron-binding protein, is critical for the reproduction and survival of PRMs and has been reported as a useful vaccine antigen for the control of PRMs and a candidate for the universal vaccine antigen in some tick species.

Method and results

Herein, we identified and characterized FER2 in TFMs and NFM. Compared with the sequence of PRM, the ferroxidase centers of the heavy chain subunits were conserved in FER2 of TFMs and NFMs. Phylogenetic analysis revealed that FER2 belongs to clusters of secretory ferritins of mites and other arthropods. Recombinant FER2 (rFER2) proteins from PRMs, TFMs, and NFMs exhibited iron-binding abilities. Immunization with each rFER2 induced strong antibody responses in chickens, and each immune plasma cross-reacted with rFER2 from different mites. Moreover, mortality rates of PRMs fed with immune plasma against rFER2 from TFMs or NFMs, in addition to PRMs, were higher than those of control plasma.

Discussion

rFER2 from each avian mite exhibited anti-PRM effects. This data suggests that it has the potential to be used as an antigen candidate for a universal vaccine against avian mites. Further studies are needed to access the usefulness of FER2 as a universal vaccine for the control of avian mites.

Collecting and Monitoring for Northern Fowl Mite (Acari: Macronyssidae) and Poultry Red Mite (Acari: Dermanyssidae) in Poultry Systems

The two most economically important poultry ectoparasites are the northern fowl mite, Ornithonyssus sylviarum (Canestrini and Fanzago), and the poultry red mite, Dermanyssus gallinae (De Geer). Both mites are obligate blood feeders but differ in where they reside. Sampling methods thus focus on-host, especially the vent feathers, for northern fowl mite and off-host, especially cracks and crevices near the nighttime roosting areas, for poultry red mite. Much remains unknown, however, about the basic biology and ecology of both mites. Here we discuss mite detection, quantification, and decision making and provide thoughts on future directions for research.

Essential oils: effects of application rate and modality on potential for combating northern fowl mite infestations

The northern fowl mite (NFM), Ornithonyssus sylviarum (Mesostigmata: Macronyssidae), is the primary blood-feeding ectoparasite found on poultry in the U.S.A. Three experiments were conducted in vitro to test the acaricidal properties of cade, garlic, lavender, lemongrass, pine and thyme essential oils against NFM, and to evaluate whether these effects are altered by adjusting oil application rates and application modality (direct vs. vapour contact). Applied at the rate of 0.21 mg/cm² , the essential oils of cade, thyme, lemongrass and garlic resulted in higher NFM mortality at 24 h post-application than lavender and pine oils, and the untreated and ethanol-treated controls. Cade and thyme were the most consistent and fast-acting of the essential oils in terms of toxicity to NFM. Cade applied at 0.21 mg/cm² and 0.11 mg/cm² and thyme applied at 0.21 mg/cm² were effective in eliminating NFM within 2 h through direct contact. The modality of application did not affect the efficacy of cade and thyme essential oils. The results suggest that essential oils may be utilized as alternatives to chemical pesticides and could be used as fumigants for the control of NFM.

Sulfur Dust Bag: A Novel Technique for Ectoparasite Control in Poultry Systems

Animal welfare-driven legislation and consumer demand are changing how laying chickens are housed, thus creating challenges for ectoparasite control. Hens housed in suspended wire cages (battery cages) are usually treated with high-pressure pesticides. This application type is difficult in enriched-cage or cage-free production. Alternatives to pesticide sprays are needed in enriched-cage or cage-free systems. In this study, we tested the efficacy of sulfur dust deployed in "dust bags" for control against the northern fowl mite (Ornithonyssus sylviarum), which causes host stress, decreased egg production, and reduced feed conversion efficiency. Dust bags were hung from the tops of cages or were clipped to the inside front of cages. We also tested permethrin-impregnated plastic strips, marketed for ectoparasite control in caged or cage-free commercial and backyard flocks. Previous work has shown sulfur to be very active against poultry ectoparasites; however, we found that the placement of bags was important for mite control. Sulfur in hanging bags reduced mites on treatment birds by 95 or 97% (depending on trial) within one week of being deployed, and mite counts on these birds were zero after 2 wk. Clipped sulfur bags acted more slowly and did not significantly reduce mites in one trial, but reduced mite counts to zero after 4 wk in trial 2. Permethrin strips had no effect on mite populations. This may have been due to mite resistance, even though this mite population had not been exposed to pyrethroids for several years. Sulfur bags should be effective in caged or cage-free systems.

Northern fowl mite (Ornithonyssus sylviarum) in Sweden

Haematophagous mites were collected from the vent region and plumage of chickens in six hobby flocks of ornamental breeds in Sweden, one of which included turkeys. Soiled vent skin and feathers, dermatitis, hyperkeratosis, skin necroses and ulcers were observed in 12 necropsied birds from two of the flocks. The mites were identified as the northern fowl mite Ornithonyssus sylviarum (Mesostigmata: Macronyssidae). This was supported by sequence analysis of a 642-bp region in the mitochondrial cytochrome oxidase subunit 1 (COI) gene (COI) in mites collected from five flocks, which showed 97-99% sequence similarity to O. sylviarum by blast analysis. Pairwise sequence comparisons revealed nucleotide variations in the range of 0-2.8%, whereas amino acid sequences were highly conserved. This paper represents one of very few records of O. sylviarum in European poultry, and is the first to report COI sequence data for O. sylviarum from poultry in Europe.

Use of Beauveria bassiana to control northern fowl mites (Ornithonyssus sylviarum) on roosters in an agricultural research facility

Treatment of Northern fowl mite (Ornithonyssus sylviarum) infestation on poultry in research facilities can be challenging. The mite has a rapid reproductive cycle (egg to adult in 5 to 7 d), and chemical treatments can be toxic to birds, personnel, and the environment. In addition, antimite treatment may interfere with experimental research designs. The current study evaluated the efficacy of topical application of an entomopathogenic fungus, Beauveria bassiana, in the treatment of a naturally occurring infestation of Northern fowl mites in pen-housed roosters (n = 14; age, 18 mo). Two groups of 7 roosters each were used in 2 experiments: Beauveria (30 mL, 2.9 × 10(10) spores per bird) compared with water (30 mL, control), and Beauveria compared with the common topical organophosphate agent tetrachlorvinphos-dichlorvos (30 mL). We also assessed a higher dose of Beauveria (300 mL, 2.9 × 10(11) spores per bird) in the 7 birds that were not exposed to tetrachlorvinphos-dichlorvos. Beauveria reduced mite levels relative to the control group but did not outperform tetrachlorvinphos-dichlorvos when used at an equal volume and frequency. Increasing the volume and frequency of Beauveria application improved outcomes such that visual inspection failed to detect any mites. The results presented here suggest that, when applied in sufficient doses, Beauveria effectively reduces mites on poultry and can be an important part of an integrated pest management program. Additional research is needed to document the most effective dose, frequency, and location of B. bassiana application to control Northern fowl mites in poultry.