Publications

4044

Abstract Mycoplasma haemofelis (Mhf), Candidatus Mycoplasma haemominutum (CMhm), and Candidatus Mycoplasma turicensis (CMt) are the major feline hemotropic Mycoplasma (FHM) species identified in cats worldwide. Data concerning FHM in Egypt is limited; therefore, the current study aimed to gain further insights into disease epidemiology by investigating FHM molecular prevalence, risk factors, and hemogram abnormalities in 246 Egyptian cats (shelter-housed and client-owned) during 2022–2024. Additionally, 16 S rRNA gene-based maximum-likelihood (ML) phylogenetic analysis was performed for all CMt-positive samples for the first time in Egypt. FHM was detected in 16.3% (n = 40) of cats and typed as CMhm, Mhf, and CMt in 15.4% (n = 38), 3.6% (n = 9), and 2.4% (n = 6) of cats, respectively. Single CMhm and Mhf infections were detected in 12.6% (n = 31) and 0.8% (n = 2) of cats, respectively. Dual (Mhf and CMhm) and triple (Mhf, CMhm, and CMt) infections were found in 0.4% (n = 1) and 2.4% (n = 6) of cats, respectively. CMhm was significantly associated with single infections rather than coinfections compared to other FHM species. Male sex and anemia were identified as predictors of FHM PCR positivity. FHM-infected cats had significantly lower hematocrit %, RBC counts, and hemoglobin concentrations than non-infected ones. Egyptian CMt sequences showed 97.6–100% nucleotide identity with each other. Egyptian and reference CMt strains represented nine nucleotide sequence types clustered into three well-supported clades on the ML tree without clear geographic distinction. The data generated in this study, conducted in Egypt, is crucial for enhancing our understanding of disease epidemiology and implementing effective preventive measures.

Psyllids (Hemiptera: Psylloidea) are the main vectors of various phloem-limited plant pathogens, including ‘Candidatus Liberibacter’ species. ‘Candidatus Liberibacter solanacearum’ (CLso) has been associated with various plant disorders and economic losses in plants from the Solanaceae and Apiaceae families. Recently, it has been reported in Europe, primarily linked to carrots and celery. This situation presents a significant threat, prompting the need for a survey to assess the presence of the bacterium and its potential vectors. Plant and psyllid samples were collected from potato (Solanum tuberosum), carrot (Daucus carota) and other wild weed species in commercial fields and urban areas over two consecutive years (2022 and 2023). DNA was extracted from the samples, followed by conventional PCR and the sequencing of positive samples. The psyllid species Bactericera nigricornis was the dominant species in potato fields, while Bactericera trigonica was the most abundant in carrot fields, followed by Heterotrioza chenopodii, ranking as the second most abundant species in both cases. CLso-positive samples were found in D. carota, B. trigonica, H. chenopodii, B. nigricornis, and Trioza urticae. The sequencing results suggest the detected haplotypes are D and U. These findings raise concerns about the potential spread of CLso and the associated risk of significant economic losses.

Background. Rickettsia are obligate intracellular gram-negative bacteria of the class Alphaproteobacteria and are vector-borne species that cause diseases in humans and animals. New Rickettsia species have been involved as human pathogens; however, the pathogenic potential of other species is unknown. Candidatus Rickettsia colombiensis is a new species in the spotted fever group of unknown pathogenicity that is phylogenetically related to other pathogenic species. Objetive. To evaluate the pathogenic potential of Ca. R. colombiensis in Syrian hamsters (Mesocricetus auratus) and analyzed its cross-reactivity against other SFG rickettsia species in human and Syrian hamster sera. Methods. Ca. R. colombiensis was isolated from Amblyomma dissimile using a shell vial. Subsequently, five male hamsters were inoculated intraperitoneally (IP) and five intradermally (ID) with 1 × 106 Vero cells infected with Ca. R. colombiensis. One control animal was used in each group of the study. The health status of the animals was assessed daily, and necropsies were performed on days 5, 10, 15, and 16 DPI. Serum samples for indirect immunofluorescence and tissues were processed for qPCR and immunohistochemistry. Results. All animals remained healthy during the trial and showed no changes in their physiological parameters. No Rickettsia DNA was detected in any of the tissues. Animals infected with Ca. R. colombiensis showed IgG antibody titers ranging from 1:64 to 1:1024. The control animals were negative. Regarding human sera, 56% (84/150) had IgG antibodies against Ca. R. colombiensis antigen. Sera with titers equal to or higher than 1:64 were 100% seroreactive. Conclusions. Ca. R. colombiensis caused a subclinical infection in hamsters, suggesting the possibility of infecting other mammals. However, the clinical, pathological, and molecular findings are inconclusive in establishing that Ca. R. colombiensis is a pathogenic species. Regarding cross-reactivity, it is possible to serologically diagnose Rickettsial infection using Ca. R. colombiensis as antigens.

Abstract The genus “Candidatus Kouleothrix” (Eikelboom type 1851) is the major filamentous bacterium responsible for activated sludge bulking in Japanese activated sludge plants, where it is present in many in unusually high abundances. Global surveys have shown this genus embraces several species, although the contribution each of these makes to bulking is not known. This study followed their population dynamics in a full-scale bulking sludge plant in Japan over a 12-month period, which required the development of species-specific FISH probes, used to measure their relative abundances. Six of the 9 recognised species of “Ca. Kouleothrix” were detected there, two of which (midas_s_3423 and midas_s_35412) were at consistently high abundances and responsible for increases in the sludge volume index (SVI). Their abundances were also statistically correlated with their filament lengths, which showed higher correlations with SVI increases than did species abundances. This study examined the impacts of both operational parameters and other communities on the abundances of these two species over the 12-month period and showed marked interspecies differences in responses to both. Together these findings stress the importance in studies of this kind to identify populations to species level to reveal possible important ecological differences not seen at the genus level.

'Candidatus Phytoplasma pyri', the pathogen associated with pear decline, affects pear trees across both the old and new worlds. However, research on this phytoplasma has been limited by the lack of genomic data. This study presents the first draft genome of 'Ca. P. pyri' using a strain from Chile, with its genomic features analyzed in comparison to the closely related 'Ca. Phytoplasma' species, 'Ca. P. mali' and 'Ca. P. prunorum'. The draft genome spans 456,478 bp with a GC content of 20.4%. Key genes possibly associated with pathogenicity and potential pathogenic effectors were identified, and they are notably lacking orthologs of known effectors. A single potential mobile unit similar to that of 'Ca. P. mali' was identified. It is characterized by the absence of the transposase tra5 and the presence of the IS3 family transposase iSErh1. Multilocus sequence analysis (MLSA) of six genetic markers (16S rRNA gene, LSU36p, tuf, aceF, secA, and secY) from ten Chilean and ten Italian samples revealed high genetic uniformity among the Chilean strains, collected from five geographically distant orchards over a span of 13 months; by contrast, strains with greater diversity were detected among those from Italy collected from a few localities over approximately 30 years. These findings suggest limited evolutionary divergence of this phytoplasma in Chile. This study provides a foundational framework for investigations into the pathogenic mechanisms and evolutionary dynamics of 'Ca. P. pyri'.

ABSTRACT The Coxiellaceae bacterial family, within the order Legionellales, is defined by a collection of poorly characterized obligate intracellular bacteria. The zoonotic pathogen and causative agent of human Q fever, Coxiella burnetii , represents the best-characterized member of this family. Coxiellaceae establish replicative niches within diverse host cells and rely on their host for survival, making them challenging to isolate and cultivate within a laboratory setting. Here, we describe a new genus within the Coxiellaceae family that has been previously shown to infect economically significant freshwater crayfish. Using culture-independent long-read metagenomics, we reconstructed the complete genome of this novel organism and demonstrate that the species previously referred to as Candidatus Coxiella cheraxi represents a novel genus within this family, herein denoted Candidatus Paracoxiella cheracis . Interestingly, we demonstrate that Candidatus P. cheracis encodes a complete, putatively functional Dot/Icm type 4 secretion system that likely mediates the intracellular success of this pathogen. In silico analysis defined a unique repertoire of Dot/Icm effector proteins and highlighted homologs of several important C. burnetii effectors, including a homolog of CpeB that was demonstrated to be a Dot/Icm substrate in C. burnetii . IMPORTANCE Using long-read sequencing technology, we have uncovered the full genome sequence of Candidatus Paracoxiella cheracis , a pathogen of economic importance in aquaculture. Analysis of this sequence has revealed new insights into this novel member of the Coxiellaceae family, demonstrating that it represents a new genus within this poorly characterized family of intracellular organisms. Importantly, the genome sequence reveals invaluable information that will support diagnostics and potentially both preventative and treatment strategies within crayfish breeding facilities. Candidatus P. cheracis also represents a new member of Dot/Icm pathogens that rely on this system to establish an intracellular niche. Candidatus P. cheracis possesses a unique cohort of putative Dot/Icm substrates that constitute a collection of new eukaryotic cell biology-manipulating effector proteins.