Infectious Diseases


Publications (233)

Pathogenicity and Transcriptomic Analyses of Two “ <i>Candidatus</i> Liberibacter asiaticus” Strains Harboring Different Types of Phages

Citation
Zheng et al. (2023). Microbiology Spectrum
Names
Ca. Liberibacter asiaticus
Subjects
Cell Biology Ecology General Immunology and Microbiology Genetics Infectious Diseases Microbiology (medical) Physiology
Abstract
Citrus Huanglongbing (HLB), also called citrus greening disease, is a highly destructive disease threatening citrus production worldwide. “ Candidatus Liberibacter asiaticus” is one of the most common putative causal agents of HLB. Phages of “ Ca . Liberibacter asiaticus”

Environmental Factors Affect the Bacterial Community in <i>Diaphorina citri</i> , an Important Vector of “ <i>Candidatus</i> Liberibacter asiaticus”

Citation
Jiang et al. (2023). Microbiology Spectrum 11 (2)
Names
Ca. Liberibacter asiaticus
Subjects
Cell Biology Ecology General Immunology and Microbiology Genetics Infectious Diseases Microbiology (medical) Physiology
Abstract
The Asian citrus psyllid (ACP) is an important vector of the HLB pathogen, which is a major threat to citrus production around the world. Bacterial communities harbored by insects could be affected by different environmental factors.

Citrus tristeza virus Promotes the Acquisition and Transmission of ‘Candidatus Liberibacter Asiaticus’ by Diaphorina citri

Citation
Chen et al. (2023). Viruses 15 (4)
Names
Ca. Liberibacter asiatus Liberibacter
Subjects
Infectious Diseases Virology
Abstract
Diaphorina citri Kuwayama (D. citri) is an insect vector of phloem-limited ‘Candidatus Liberibacter asiatus’ (CLas), the presumed pathogen of citrus Huanglongbing (HLB). Recently, our lab has preliminarily found it acquired and transmitted Citrus tristeza virus (CTV), which was previously suggested to be vectored by species of aphids. However, the influences of one of the pathogens on the acquisition and transmission efficiency of the other pathogen remain unknown. In this study, CLas and CTV acquisition and transmission by D. citri at different development stages under field and laboratory conditions were determined. CTV could be detected from the nymphs, adults, and honeydew of D. citri but not from the eggs and exuviates of them. CLas in plants might inhibit CTV acquisition by D. citri as lower CTV–positive rates and CTV titers were detected in D. citri collected from HLB-affected trees compared to those from CLas–free trees. D. citri were more likely to obtain CTV than CLas from host plants co-infected with the two pathogens. Intriguingly, CTV in D. citri facilitated the acquisition and transmission of CLas, but CLas carried by D. citri had no significant effect on the transmission of CTV by the same vector. Molecular detection and microscopy methods confirmed the enrichment of CTV in the midgut after a 72-h acquisition access period. Collectively, these results raise essential scientific questions for further research on the molecular mechanism of pathogen transmission by D. citri and provide new ideas for the comprehensive prevention and control of HLB and CTV.

‘Candidatus Rickettsia andeanae’ and Probable Exclusion of Rickettsia parkeri in Ticks from Dogs in a Natural Area of the Pampa Biome in Brazil

Citation
Krawczak et al. (2023). Pathogens 12 (3)
Names
Ca. Rickettsia andeanae
Subjects
General Immunology and Microbiology Immunology and Allergy Infectious Diseases Microbiology (medical) Molecular Biology
Abstract
Spotted fever illness caused by the tick-borne pathogen Rickettsia parkeri has emerged in the Pampa biome in southern Brazil, where the tick Amblyomma tigrinum is implicated as the main vector. Because domestic dogs are commonly parasitized by A. tigrinum, this canid is also a suitable sentinel for R. parkeri-associated spotted fever. Herein, we investigate rickettsial infection in ticks, domestic dogs and small mammals in a natural reserve of the Pampa biome in southern Brazil. The ticks A. tigrinum, Amblyomma aureolatum and Rhipicephalus sanguineus were collected from dogs. Molecular analyses of ticks did not detect R. parkeri; however, at least 34% (21/61) of the A. tigrinum ticks were infected by the non-pathogenic agent ‘Candidatus Rickettsia andeanae’. Serological analyses revealed that only 14% and 3% of 36 dogs and 34 small mammals, respectively, were exposed to rickettsial antigens. These results indicate that the study area is not endemic for R. parkeri rickettsiosis. We tabulated 10 studies that reported rickettsial infection in A. tigrinum populations from South America. There was a strong negative correlation between the infection rates by R. parkeri and ‘Candidatus R. andeanae’ in A. tigrinum populations. We propose that high infection rates by ‘Candidatus R. andeanae’ might promote the exclusion of R. parkeri from A. tigrinum populations. The mechanisms for such exclusion are yet to be elucidated.