Infectious Diseases

Bois noir (BN), associated with ‘Candidatus Phytoplasma solani’ (CaPsol), is the most widespread disease of the grapevine yellows complex worldwide. In this work, BN epidemiology was investigated in a case study vineyard where an unusual CaPsol strain, previously detected only in other host plants, was found to be prevalent in grapevine. Experimental activities included: symptom observation; sampling of symptomatic vines, Auchenorrhyncha specimens, and weeds; molecular detection and typing of CaPsol strains; statistical analyses for determining possible relationships between CaPsol relative concentration, strain type, and symptom severity. Among insects, Reptalus quinquecostatus was the most abundant and was found to be highly infected by CaPsol, while Hyalesthes obsoletus, the main CaPsol vector, was not caught. Moreover, R. quinquecostatus harbored CaPsol strains carrying uniquely the stamp sequence variant St10, also identified as prevalent in vines and in the majority of weeds, and all the secY variants identified in the vineyard. Statistical analyses revealed that CaPsol strains carrying the St10 variant are not associated with severe symptoms, suggesting their possible moderate virulence. Based on such evidence, a new BN epidemiological pattern related to these CaPsol strains and involving grapevine, R. quinquecostatus, and/or weeds is proposed. Furthermore, the possible presence of other players (vectors and weeds) involved in CaPsol transmission to grapevines was highlighted.

Abstract Background Hemotropic mycoplasmas (hemoplasmas) infect animals and humans and can lead to clinical syndromes mainly characterized by hemolytic anemia. A novel pathogen, Candidatus Mycoplasma haemohominis, was recently associated with a case of human hemoplasmosis in Europe. Here we report the first detection of this pathogen in an Australian patient exhibiting persistent fever, hemolytic anemia, and pancytopenia over a 10-month period. Methods After exhaustive negative testing for human infectious diseases, whole genome sequencing (WGS) was performed on the patient’s bone marrow aspirate, using an Illumina NextSeq500 platform. Conventional polymerase chain reaction (PCR), followed by Sanger sequencing, was then performed on blood samples using novel Mycoplasma-specific primers targeting the 16S ribosomal RNA gene. In addition, a Mycoplasma-specific fluorescence in situ hybridization (FISH) assay was developed to differentiate Mycoplasma cells from other erythrocyte inclusions (eg, Pappenheimer and Howell-Jolly bodies) which are morphologically similar to bacterial cocci by light microscopy. Results WGS analysis revealed that approximately 0.04% of the total number of unmapped reads to human genome corresponded to Mycoplasma species. A 1-kb Mycoplasma 16S fragment was successfully amplified by conventional PCR, and sequence analyses revealed 100% identity with Candidatus Mycoplasma haemohominis. FISH confirmed that several (approximately 2%) epierythrocytic inclusions initially observed by light microscopy corresponded to Mycoplasma cells. Conclusions This represents the second report of hemolytic anemia associated with hemoplasma infection in a human, and the first report of human hemoplasmosis in Australia. This study highlights the importance of new and emerging diagnostic approaches and need for further investigations on the epidemiology of Candidatus Mycoplasma haemohominis in Australia.