Nosema apis
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Nosemosis is a microsporidian disease causing mortality and weakening of honey bee colonies, especially in the event of co-exposure to other sources of stress. As a result, the disease is regulated in some countries. Reliable and harmonised diagnosis is crucial to ensure the quality of surveillance and research results. For this reason, the first European Interlaboratory Comparison (ILC) was organised in 2017 in order to assess both the methods and the results obtained by National Reference Laboratories (NRLs) in counting Nosema spp. spores by microscopy. Implementing their own routine conditions of analysis, the 23 participants were asked to perform an assay on a panel of ten positive and negative samples of crushed honey bee abdomens. They were asked to report results from a qualitative and quantitative standpoint. The assessment covered specificity, sensitivity, trueness and precision. Quantitative results were analysed in compliance with international standards NF ISO 13528 (2015) and NF ISO 5725-2 (1994). Three results showed a lack of precision and five a lack of trueness. However, overall results indicated a global specificity of 98% and a global sensitivity of 100%, thus demonstrating the advanced performance of the microscopic methods applied to Nosema spores by the NRLs. Therefore, the study concluded that using microscopy to detect and quantify spores of Nosema spp. was reliable and valid.
- MeSH
- břicho mikrobiologie MeSH
- laboratoře MeSH
- mikroskopie metody MeSH
- Nosema cytologie izolace a purifikace MeSH
- spory hub cytologie izolace a purifikace MeSH
- včely mikrobiologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- práce podpořená grantem MeSH
Hexokinase (HXK) is the first key enzyme in the glycolytic pathway and plays an extremely important role in energy metabolism. By searching the microsporidian database, we found a sequence (NBO_27g0008) of Nosema bombycis Nägali, 1857 with high similarity to hexokinase-2, and named it as NbHXK2. The NbHXK2 gene has 894 bp and encodes 297 amino acids with 34.241 kD molecular weight and 5.26 isoelectric point. NbHXK2 contains 31 phosphorylation sites and 4 potential N-glycosylation sites with signal peptides and no transmembrane domain. Multiple sequence alignment showed that NbHXK2 shares more than 40% amino acid identity with that of other microsporidia, and the homology with hexokinase-2 of Nosema tyriae Canning, Curry, Cheney, Lafranchi-Tristem, Kawakami, Hatakeyama, Iwano et Ishihara, 1999, Nosema pyrausta (Paillot, 1927) and Nosema ceranae Fries, Feng, da Silva, Slemenda et Pieniazek, 1996 was 89.17%, 87.82% and 69.86%, respectively. Phylogenetic analysis based on the amino acid sequence of hexokinase showed that all microsporidia cluster together in the same clade, and are far away from animals, plants and fungi, and that N. bombycis is closely related to N. tyriae; N. pyrausta; N. ceranae and Nosema apis Zander, 1909. Immunolocalisation with the prepared polyclonal antibody showed that NbHXK2 was mainly distributed in the cytoplasm and plasmalemma in proliferative, sporulation stage and mature spore of N. bombycis. qRT-PCR assay showed that the NbHXK2 expressed at higher level during spore germination and at early stage of proliferation. These results indicate that N. bombycis may use its own glycolytic pathways to supply energy for infection and development, especially germination and in the early stage of proliferation, and acquire energy from the host through certain ways as well.
Here, we present the results of a 2-year field trial aimed at testing the effect of overwintering on different feeds on the course of Nosema ceranae infection. In August 2015, four experimental bee colony groups were established. After the last honey harvest, each colony was provided with 20 kg of feed, either honey, sugar (3:2 solution in tap water), inverted syrup made of sucrose, or wheat starch syrup. Samples of live bees were collected from each beehive in August (before feeding), November, and May. The following year, feeding and sampling were performed in the same way. Bees were examined microscopically to estimate the percentage of Nosema-infected individuals in the sample and the spore number per bee. Fitness parameters were also measured in all colonies. In all hives, presence of N. ceranae was confirmed through polymerase chain reaction. Nosema apis was not detected in the apiary. Significant differences in nosematosis prevalence and/or intensity were observed between the experimental groups. For most parameters, best results were recorded in the group fed with honey. Worst fitness and highest nosematosis prevalence and intensity were found in colonies fed with wheat starch syrup.
The honey bee, Apis mellifera, is a globally important species that suffers from a variety of pathogens and parasites. These parasites and pathogens may have sublethal effects on their bee hosts via an array of mechanisms, including through a change in symbiotic bacterial taxa. Our aim was to assess the influence of four globally widespread parasites and pathogens on the honey bee bacteriome. We examined the effects of the ectoparasitic mite Varroa destructor, the fungal pathogens Nosema apis and Nosema ceranae, and the trypanosome Lotmaria passim. Varroa was detected by acaricidal treatment, Nosema and L. passim by PCR, and the bacteriome using MiSeq 16S rRNA gene sequencing. Overall, the 1,858,850 obtained sequences formed 86 operational taxonomic units (OTUs) at 3 % dissimilarity. Location, time of year, and degree of infestation by Varroa had significant effects on the composition of the bacteriome of honey bee workers. Based on statistical correlations, we found varroosis more important factor than N. ceranae, N. apis, and L. passim infestation influencing the honey bee bacteriome and contributing to the changes in the composition of the bacterial community in adult bees. At the population level, Varroa appeared to modify 20 OTUs. In the colonies with high Varroa infestation levels (varroosis), the relative abundance of the bacteria Bartonella apis and Lactobacillus apis decreased. In contrast, an increase in relative abundance was observed for several taxa including Lactobacillus helsingborgensis, Lactobacillus mellis, Commensalibacter intestini, and Snodgrassella alvi. The results showed that the "normal" bacterial community is altered by eukaryotic parasites as well as displaying temporal changes and changes associated with the geographical origin of the beehive.
- MeSH
- Bartonella klasifikace genetika izolace a purifikace MeSH
- infestace roztoči patologie MeSH
- Kinetoplastida patogenita MeSH
- Lactobacillus klasifikace genetika izolace a purifikace MeSH
- mikrobiota genetika MeSH
- Nosema patogenita MeSH
- RNA ribozomální 16S genetika MeSH
- symbióza MeSH
- Varroidae patogenita MeSH
- včely mikrobiologie parazitologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
