Characterization of a pangolin SARS-CoV-2-related virus isolate that uses the human ACE2 receptor.

Various SARS-CoV-2-related coronaviruses have been increasingly identified in pangolins, showing a potential threat to humans. Here we report the infectivity and pathogenicity of the SARS-CoV-2-related virus, PCoV-GX/P2V, which was isolated from a Malayan pangolin (Manis javanica). PCoV-GX/P2V could grow in human hepatoma, colorectal adenocarcinoma cells, and human primary nasal epithelial cells. It replicated more efficiently in cells expressing human angiotensin-converting enzyme 2 (hACE2) as SARS-CoV-2 did. After intranasal inoculation to the hACE2-transgenic mice, PCoV-GX/P2V not only replicated in nasal turbinate and lungs, but also caused interstitial pneumonia, characterized by infiltration of mixed inflammatory cells and multifocal alveolar hemorrhage. Existing population immunity established by SARS-CoV-2 infection and vaccination may not protect people from PCoV-GX/P2V infection. These findings further verify the hACE2 utility of PCoV-GX/P2V by in vivo experiments using authentic viruses and highlight the importance for intensive surveillance to prevent possible cross-species transmission.

New insights into the impact of microbiome on horizontal and vertical transmission of a tick-borne pathogen.

BACKGROUND: The impact of host skin microbiome on horizontal transmission of tick-borne pathogens , and of pathogen associated transstadial and transovarial changes in tick microbiome are largely unknown, but are important to control increasingly emerging tick-borne diseases worldwide. METHODS: Focusing on a rickettsiosis pathogen, Rickettsia raoultii, we used R. raoultii-positive and R. raoultii-negative Dermacentor spp. tick colonies to study the involvement of skin microbiota in cutaneous infection with rickettsiae in laboratory mice, and the function of the tick microbiome on maintenance of rickettsiae through all tick developmental stages (eggs, larvae, nymphs, adults) over two generations. RESULTS: We observed changes in the skin bacteria community, such as Chlamydia, not only associated with rickettsial colonization but also with tick feeding on skin. The diversity of skin microbiome differed between paired tick-bitten and un-bitten sites. For vertical transmission, significant differences in the tick microbiota between pathogenic rickettsia-positive and -negative tick chorts was observed across all developmental stages at least over two generations, which appeared to be a common pattern not only for R. raoultii but also for another pathogenic species, Candidatus Rickettsia tarasevichiae. More importantly, bacterial differences were complemented by functional shifts primed for genetic information processing during blood feeding. Specifically, the differences in tick microbiome gene repertoire between pathogenic Rickettsia-positive and -negative progenies were enriched in pathways associated with metabolism and hormone signals during vertical transmission. CONCLUSIONS: We demonstrate that host skin microbiome might be a new factor determining the transmission of rickettsial pathogens through ticks. While pathogenic rickettsiae infect vertebrate hosts during blood-feeding by the tick, they may also manipulate the maturation of the tick through changing the functional potential of its microbiota over the tick's life stages. The findings here might spur the development of new-generation control methods for ticks and tick-borne pathogens. Video Abstract.

Metavirome of 31 tick species provides a compendium of 1,801 RNA virus genomes.

The increasing prevalence and expanding distribution of tick-borne viruses globally have raised health concerns, but the full repertoire of the tick virome has not been assessed. We sequenced the meta-transcriptomes of 31 different tick species in the Ixodidae and Argasidae families from across mainland China, and identified 724 RNA viruses with distinctive virome compositions among genera. A total of 1,801 assembled and complete or nearly complete viral genomes revealed an extensive diversity of genome architectures of tick-associated viruses, highlighting ticks as a reservoir of RNA viruses. We examined the phylogenies of different virus families to investigate virome evolution and found that the most diverse tick-associated viruses are positive-strand RNA virus families that demonstrate more ancient divergence than other arboviruses. Tick-specific viruses are often associated with only a few tick species, whereas virus clades that can infect vertebrates are found in a wider range of tick species. We hypothesize that tick viruses can exhibit both 'specialist' and 'generalist' evolutionary trends. We hope that our virome dataset will enable much-needed research on vertebrate-pathogenic tick-associated viruses.

Coinfection of Two Rickettsia Species in a Single Tick Species Provides New Insight into Rickettsia-Rickettsia and Rickettsia-Vector Interactions.

Rickettsiae are obligate intracellular bacteria that can cause life-threatening illnesses. There is an ongoing debate as to whether established infections by one Rickettsia species preclude the maintenance of the second species in ticks. Here, we identified two Rickettsia species in inoculum from Haemaphysalis montgomeryi ticks and subsequently obtained pure isolates of each species by plaque selection. The two isolates were classified as a transitional group and spotted fever group rickettsiae and named Rickettsia hoogstraalii str CS and Rickettsia rhipicephalii str EH, respectively. The coinfection of these two Rickettsia species was detected in 25.6% of individual field-collected H. montgomeryi. In cell culture infection models, R. hoogstraalii str CS overwhelmed R. rhipicephalii str EH with more obvious cytopathic effects, faster plaque formation, and increased cellular growth when cocultured, and R. hoogstraalii str CS seemed to polymerize actin tails differently from R. rhipicephalii str EH in vitro. This work provides a model to investigate the mechanisms of both Rickettsia-Rickettsia and Rickettsia-vector interactions. IMPORTANCE The rickettsiae are a group of obligate intracellular Gram-negative bacteria that include human pathogens causing an array of clinical symptoms and even death. There is an important question in the field, that is whether one infection can block the superinfection of other rickettsiae. This work demonstrated the coinfection of two Rickettsia species in individual ticks and further highlighted that testing the rickettsial competitive exclusion hypothesis will undoubtedly be a promising area as methods for bioengineering and pathogen biocontrol become amenable for rickettsiae.

Virome and Blood Meal-Associated Host Responses in Ixodes persulcatus Naturally Fed on Patients.

The long-lasting co-evolution of ticks with pathogens results in mutual adaptation. Blood-feeding is one of the critical physiological behaviors that have been associated with the tick microbiome; however, most knowledge was gained through the study of laboratory-reared ticks. Here we detached Ixodes persulcatus ticks at different stages of blood-feeding from human patients and performed high-throughput transcriptomic analysis on them to identify their virome and genes differentially expressed between flat and fully fed ticks. We also traced bloodmeal sources of those ticks and identified bats and three other potential mammalian hosts, highlighting the public health significance. We found Jingmen tick virus and 13 putative new viruses belonging to 11 viral families, three of which even exhibited high genetic divergence from viruses previously reported in the same tick species from the same geographic region. Furthermore, differential expression analysis suggested a downregulation of antioxidant genes in the fully fed I. persulcatus ticks, which might be related to bloodmeal-related redox homeostasis. Our work highlights the significance of active surveillance of tick viromes and suggests a role of reactive oxygen species (ROS) in modulating changes in the microbiome during blood-feeding.

Klinefelter's syndrome (47,XXY) among men with systemic lupus erythematosus.

AIM: To determine the rate of Klinefelter's syndrome among men with systemic lupus erythematosus (SLE), and to determine whether the manifestations of SLE in these men are different from that seen in 46,XY men. METHODS: A total of 276 men with SLE underwent a real-time PCR procedure to screen for more than one X chromosome. Those with results consistent with two X chromosomes were further characterized by karyotype and FISH. Clinical manifestations of SLE were determined by interview, questionnaire and medical chart review. Each man with Klinefelter's and SLE was matched to four 46,XY men with SLE. Rates of SLE manifestations were compared with chi-square analyses. RESULTS: We found seven of the 286 men with SLE had Klinefelter's syndrome. Four of these seven were nonmosaic 47,XXY, while two were mosaic 46,XY/47,XXY and one was 46,XX/47,XXY. The men with 47,XXY did not have severe manifestations of SLE including no proliferative renal disease, neurological disease, thrombocytopenia, autoimmune haemolytic anaemia, discoid skin disease or anti-RNP/Sm. CONCLUSION: 47,XXY is found in excess among men with SLE. Men commonly have SLE that is more severe than that found among women, but the 47,XXY men had less severe SLE than other men.