Publications

4641

Abstract Background ‘ Candidatus Liberibacter solanacearum’ (Lso) is a phloem-limited bacterial pathogen causing significant diseases in solanaceous crops. In the United States, haplotypes A and B are transmitted by the potato psyllid Bactericera cockerelli . We previously identified differences in their acquisition and transmission between adults and nymphs. The present study characterized the dynamics of LsoA and LsoB acquisition and transmission by nymphs and examined the transcriptional responses of the nymphal gut upon their acquisition. Methods and results Nymphs were exposed to LsoA- or LsoB-infected plants for 1, 3, 5, or 7 days to measure the bacterial accumulation and for 8 days to assess the transmission efficiency following sequential inoculation of tomato plants. Quantitative PCR showed that LsoB accumulated to higher levels than LsoA after 3 days of acquisition. Following the sequential inoculation, LsoB was transmitted earlier than LsoA indicating a shorter latency period. RNA-seq analysis of the guts following a 1- and 5-day acquisition access periods revealed a greater transcriptional regulation at 5 days than at 1 day. Furthermore, the responses were haplotype-specific: LsoA primarily affected genes involved in protein translation, ER stress, and cell cycle regulation, whereas LsoB regulated genes involved in autophagy, apoptosis, and immune pathways. Conclusions This study revealed haplotype-specific gene regulation potentially leading to LsoB being transmitted more efficiently by psyllid nymphs.

Abstract Bovine hemoplasmas, including Mycoplasma wenyonii (M. wenyonii) and Candidatus Mycoplasma haemobos (C. M. haemobos) , are vector-borne pathogens that can cause significant clinical diseases in cattle. This case report from Türkiye describes the clinical findings, hematological analysis, and serum biochemistry results of a cow presenting with hemoglobinuria caused by C. M. haemobos . Blood samples from the infected animal were analyzed using hematological, biochemical, microscopic, and molecular methods. Multiplex polymerase chain reaction assay confirmed the infection, and microscopic analysis revealed a parasitemia rate of 6.99%. Clinical signs included hemoglobinuria, icterus, and anemia. The treatment included fluid therapy, antibiotic (oxytetracycline), and antianemic drugs. The cattle died 1 month post-treatment, reportedly due to a lower respiratory tract infection. This case report describes the diagnostic methods, clinical findings, and laboratory results. A widescale molecular survey of C. M. haemobos in cattle is warranted, with investigation of its pathogenicity and pathogenies.

Background: The Asian Haemaphysalis longicornis is capable of transmitting a wide range of zoonotic pathogens. This study aimed to investigate the prevalence and characteristics of major pathogens in questing H. longicornis ticks collected from two geographically and ecologically distinct regions in China. Methods: A total of 1004 questing H. longicornis ticks were collected from Liaoning Province (Northeast China; n = 882) and Anhui Province (Central and Eastern China; n = 122) and pooled into 670 mixed samples. Tick species were identified by mitochondrial cytochrome oxidase I gene sequencing. Nucleic acid samples from all pools were first screened for Dabie bandavirus using RT-PCR and for bacteria using universal 16S rRNA primers. Bacteria-positive samples were further tested using polygenic seminested PCR for Rickettsia spp. and Coxiella -like endosymbionts (CLEs). Phylogenetic analyses, including polygene sequence analysis, were performed to ensure the accuracy of species identification and to explore genetic relationships. Results: No Dabie bandavirus was detected in any samples. Among the 670 tick pools, 14 were positive for spotted fever group rickettsiae (SFGR), with an overall minimum infection rate (MIR) of 1.4% (14/1004). Notably, the detected SFGR species showed clear geographic segregation: Candidatus Rickettsia jingxinensis was detected only in Liaoning Province (MIR of 1.4%), while Rickettsia heilongjiangensis was found exclusively in Anhui Province (MIR of 1.6%). Additionally, CLEs (overall MIR of 2.0%) were identified in 20 tick pools, with a significantly higher prevalence in Anhui Province (10.7%) than in Liaoning Province (0.8%; p < 0.001). Conclusions: This surveillance revealed a distinct geographical distribution pattern of SFGR species in H. longicornis populations in China and confirmed the presence of Ca . R. jingxinensis in the northeast and R. heilongjiangensis in the central and eastern regions. These findings, supported by polygenic evidence, provide essential epidemiological data for understanding regional tick-borne disease risks and highlight the need for continued region-specific surveillance.

ABSTRACT Ponkan mandarin ( Citrus reticulata cv. Ponkan) is an important fruit crop planted across different countries. One of its most devastating diseases is citrus huanglongbing (HLB), which is associated with infection by the bacterium Candidatus Liberibacter asiaticus ( C Las). Although studies on HLB in Ponkan mandarin have been conducted, symptom heterogeneity and its association with C Las titer under field conditions remain underexplored. We examined the association between symptom variation and C Las infection status in a Ponkan mandarin grove by categorizing symptoms at both the leaf and canopy (tree) level. Chlorotic leaves were sampled and classified into different categories, including leaves exhibiting interveinal chlorosis (Cat. A), those showing vein yellowing (Cat. B), and blotchy mottled leaves (Cat. C). Polymerase chain reaction (PCR) and quantitative PCR (qPCR) assays targeting C Las revealed that Cat. A leaves, which resembled nutrient-deficient leaves, had higher C Las detection rates and a larger proportion of samples with high C Las titers. Canopy-level assessment of symptom diversity within each tree also revealed that plants bearing Cat. A leaves were more likely to carry C Las and have high pathogen loads. The likelihood was also greater in trees with higher leaf symptom diversity. Additional prophage typing of the detected C Las strains revealed that leaf symptom variations were independent of prophage type difference. Nutrient analyses revealed reduced magnesium, manganese, and zinc contents in Cat. A leaves, indicating that leaves prone to C Las infection also exhibited nutrient deficiencies. These findings highlight the complexity of potential cultivar-specific associations between C Las and citrus under field conditions. IMPORTANCE Although it is well-established that HLB in Ponkan mandarin is associated with C Las infection, the relationship between leaf symptom variation in this cultivar and the presence and titer of C Las under complex field conditions remains unclear. By examining symptom heterogeneity in natural field conditions at both the leaf and canopy level, this study demonstrated that HLB leaf symptom variation in naturally infected Ponkan mandarin corresponds to differences in C Las presence and titer at both levels. Notably, although blotchy mottling is considered the typical leaf symptom of HLB, we found that C Las detection rates and titers tended to be greater in leaves showing nutrient deficiency-like symptoms, which contrasts with patterns in other citrus cultivars. Recognizing inconsistencies among cultivar-specific patterns is important for interpreting HLB symptoms, devising sampling strategies, and exploring uncharacterized factors affecting symptom expression under field conditions.

A Gram-stain-negative, aerobic, capsule-forming strain, designated DAS-389 T , was isolated from soil collected in the Kogelberg Nature Reserve, Western Cape, South Africa. The strain formed small pink colonies, with cells that multiplied by binary division. Optimum growth was observed at 20 °C to 26 °C and pH 5.5 to 6.5, and it tolerated a NaCl concentration up to 1.5% (w/v). DAS-389 T is chemoorganotrophic, with growth substrate preferences for sugars and polysaccharides, including fructose and starch, respectively. The genome of DAS-389 T had a genome size of 4,136,282 bp with an average G+C content of 63.49 mol% and encodes for an assortment of enzymes, carbohydrate metabolic pathways and several genes involved in stress and survival responses. Major fatty acids (>5%) of strain DAS-389 T were iso-C15:0, iso-C17:0, summed feature 3 (C16:1 ω7c and/or C16:1 ω6c) and summed feature 9 (iso-C17:1 ω9c and/or C16:0 10-methyl). Comparative analysis of 16S rRNA gene sequences revealed that strain DAS-389 T shared the highest similarity with Alloacidobacterium dinghuense 4Y35 T (96.6%), followed by Acidipila rosea AP8 T (96.6%) and Paracidobacterium acidisoli 4G-K13T (96.3%). Phylogenetic analysis based on 16S rRNA gene sequences and the whole proteome placed DAS-389 T within a distinct clade, separate from recognized genera in the family Acidobacteriaceae . We therefore propose that strain DAS-389ᵀ represents a novel genus and species, Candidatus Dedyshia acidiphila gen. nov., sp. nov., within the family Acidobacteriaceae , order Terriglobia . The whole-genome sequence of strain DAS-389ᵀ [accession number: JBMGJV000000000 (PRJNA1221820) ] is designated as the nomenclatural type.