Transcriptome signatures of wastewater effluent exposure in larval zebrafish vary with seasonal mixture composition in an effluent-dominated stream.

Wastewater treatment plant (WWTP) effluent-dominated streams provide critical habitat for aquatic and terrestrial organisms but also continually expose them to complex mixtures of pharmaceuticals that can potentially impair growth, behavior, and reproduction. Currently, few biomarkers are available that relate to pharmaceutical-specific mechanisms of action. In the experiment reported in this paper, zebrafish (Danio rerio) embryos at two developmental stages were exposed to water samples from three sampling sites (0.1 km upstream of the outfall, at the effluent outfall, and 0.1 km below the outfall) during base-flow conditions from two months (January and May) of a temperate-region effluent-dominated stream containing a complex mixture of pharmaceuticals and other contaminants of emerging concern. RNA-sequencing identified potential biological impacts and biomarkers of WWTP effluent exposure that extend past traditional markers of endocrine disruption. Transcriptomics revealed changes to a wide range of biological functions and pathways including cardiac, neurological, visual, metabolic, and signaling pathways. These transcriptomic changes varied by developmental stage and displayed sensitivity to variable chemical composition and concentration of effluent, thus indicating a need for stage-specific biomarkers. Some transcripts are known to be associated with genes related to pharmaceuticals that were present in the collected samples. Although traditional biomarkers of endocrine disruption were not enriched in either month, a high estrogenicity signal was detected upstream in May and implicates the presence of unidentified chemical inputs not captured by the targeted chemical analysis. This work reveals associations between bioeffects of exposure, stage of development, and the composition of chemical mixtures in effluent-dominated surface water. The work underscores the importance of measuring effects beyond the endocrine system when assessing the impact of bioactive chemicals in WWTP effluent and identifies a need for non-targeted chemical analysis when bioeffects are not explained by the targeted analysis.

RNA-seq reveals potential gene biomarkers in fathead minnows (Pimephales promelas) for exposure to treated wastewater effluent.

Discharged wastewater treatment plant (WWTP) effluent greatly contributes to the generation of complex mixtures of contaminants of emerging concern (CECs) in aquatic environments which often contain neuropharmaceuticals and other emerging contaminants that may impact neurological function. However, there is a paucity of knowledge on the neurological impacts of these exposures to aquatic organisms. In this study, caged fathead minnows (Pimephales promelas) were exposed in situ in a temperate-region effluent-dominated stream (i.e., Muddy Creek) in Coralville, Iowa, USA upstream and downstream of a WWTP effluent outfall. The pharmaceutical composition of Muddy Creek was recently characterized by our team and revealed many compounds there were at a low microgram to high nanogram per liter concentration. Total RNA sequencing analysis on brain tissues revealed 280 gene isoforms that were significantly differentially expressed in male fish and 293 gene isoforms in female fish between the upstream and downstream site. Only 66 (13%) of such gene isoforms overlapped amongst male and female fish, demonstrating sex-dependent impacts on neuronal gene expression. By using a systems biology approach paired with functional enrichment analyses, we identified several potential novel gene biomarkers for treated effluent exposure that could be used to expand monitoring of environmental effects with respect to complex CEC mixtures. Lastly, when comparing the results of this study to those that relied on a single-compound approach, there was relatively little overlap in terms of gene-specific effects. This discovery brings into question the application of single-compound exposures in accurately characterizing environmental risks of complex mixtures and for gene biomarker identification.

Cross-species transcriptomic signatures identify mechanisms related to species sensitivity and common responses to nanomaterials.

Physico-chemical characteristics of engineered nanomaterials are known to be important in determining the impact on organisms but effects are equally dependent upon the characteristics of the organism exposed. Species sensitivity may vary by orders of magnitude, which could be due to differences in the type or magnitude of the biochemical response, exposure or uptake of nanomaterials. Synthesizing conclusions across studies and species is difficult as multiple species are not often included in a study, and differences in batches of nanomaterials, the exposure duration and media across experiments confound comparisons. Here three model species, Danio rerio, Daphnia magna and Chironomus riparius, that differ in sensitivity to lithium cobalt oxide nanosheets are found to differ in immune-response, iron-sulfur protein and central nervous system pathways, among others. Nanomaterial uptake and dissolution does not fully explain cross-species differences. This comparison provides insight into how biomolecular responses across species relate to the varying sensitivity to nanomaterials.

Reorienting Primary Health Care Services for Non-Communicable Diseases: A Comparative Preparedness Assessment of Two Healthcare Networks in Malawi and Zambia.

Despite positive NCD policies in recent years, majority of Sub-Saharan African (SSA) health systems are inadequately prepared to deliver comprehensive first-line care for NCDs. Primary health care (PHC) settings in countries like Malawi and Zambia could be a doorway to effectively manage NCDs by moving away from delivering only episodic care to providing an integrated approach over time. As part of a collaborative health system strengthening project, we assessed and compared the preparedness and operational capacity of two target networks of public PHC settings in Lilongwe (Malawi) and Lusaka (Zambia) to integrate NCD services within routine service delivery. Data was collected and analyzed using validated health facility survey tools. These baseline assessments conducted between August 2018 and March 2019, also included interviews with 20 on-site health personnel and focal persons, who described existing barriers in delivering NCD services. In both countries, policy directives to decentralize disease-specific NCD services to the primary care level were initiated to meet increased demand but lacked operational guidance. In general, the assessed PHC sites were inadequately prepared to integrate NCDs into various service delivery domains, thus requiring further support. In spite of existing multi-faceted limitations, there was motivation among healthcare staff to provide NCD services.

Factors Associated with Outpatient Satisfaction in Tertiary Hospitals in China: A Systematic Review.

Outpatient care is made up of medical procedures, tests, and services that can be provided to the patient in a setting that doesn't involve an overnight hospital stay. In China, tertiary hospitals are medical services centers of health care systems, and some tertiary hospitals had more than 20,000 outpatient visits per day. However, a systematic review of existed evidence on factors influencing the outpatient satisfaction in tertiary hospitals in China could inform the efforts and does not yet exist. Therefore, in order to better understand the outpatient satisfaction provided by tertiary hospitals in China, we carried out a systematic review following PRISMA guidelines. Studies reporting on the level of and factors associated with outpatient satisfaction in Chinese tertiary hospitals were systematically searched in both Chinese and English electronic databases. A total of 36 articles reported 35 studies that met the inclusion criteria. Out of these eight were household surveys covering 12,119 residents, and another 27 directly interviewed 45,930 outpatients during their hospital visits from 185 hospitals. The included studies generally used self-designed questionnaire and indicated there is a lack of standardized questionnaire for investigating outpatient satisfaction in China. The outpatients showed the highest satisfaction with the doctors and nurses and the lowest satisfaction with the hospital hygiene and outpatient procedures, especially with the long waiting time. The socio-demographic characteristics (e.g., age, marital status, income and education levels), professional skills and service attitudes of medical staff were reported to be associated with outpatient satisfaction. The results indicated that in China, the outpatient satisfaction can be largely improved. Firstly, the attitude of medical service providers, especially the pre-diagnosis nurses, registration officers, and pharmaceutical counters should be improved. Furthermore, to shorten the waiting time, policies should be developed to guide patients with common diseases and slight discomforts to community health systems to alleviate the overload in tertiary hospitals. Considering the strained relations between the doctors and patients in the clinical practice, improving patient satisfaction in China deserves more attention and research.

Neonatal Rhesus Macaques Have Distinct Immune Cell Transcriptional Profiles following HIV Envelope Immunization.

HIV-1-infected infants develop broadly neutralizing antibodies (bnAbs) more rapidly than adults, suggesting differences in the neonatal versus adult responses to the HIV-1 envelope (Env). Here, trimeric forms of HIV-1 Env immunogens elicit increased gp120- and gp41-specific antibodies more rapidly in neonatal macaques than adult macaques. Transcriptome analyses of neonatal versus adult immune cells after Env vaccination reveal that neonatal macaques have higher levels of the apoptosis regulator BCL2 in T cells and lower levels of the immunosuppressive interleukin-10 (IL-10) receptor alpha (IL10RA) mRNA transcripts in T cells, B cells, natural killer (NK) cells, and monocytes. In addition, immunized neonatal macaques exhibit increased frequencies of activated blood T follicular helper-like (Tfh) cells compared to adults. Thus, neonatal macaques have transcriptome signatures of decreased immunosuppression and apoptosis compared with adult macaques, providing an immune landscape conducive to early-life immunization prior to sexual debut.

High fat diet induces microbiota-dependent silencing of enteroendocrine cells.

Enteroendocrine cells (EECs) are specialized sensory cells in the intestinal epithelium that sense and transduce nutrient information. Consumption of dietary fat contributes to metabolic disorders, but EEC adaptations to high fat feeding were unknown. Here, we established a new experimental system to directly investigate EEC activity in vivo using a zebrafish reporter of EEC calcium signaling. Our results reveal that high fat feeding alters EEC morphology and converts them into a nutrient insensitive state that is coupled to endoplasmic reticulum (ER) stress. We called this novel adaptation 'EEC silencing'. Gnotobiotic studies revealed that germ-free zebrafish are resistant to high fat diet induced EEC silencing. High fat feeding altered gut microbiota composition including enrichment of Acinetobacter bacteria, and we identified an Acinetobacter strain sufficient to induce EEC silencing. These results establish a new mechanism by which dietary fat and gut microbiota modulate EEC nutrient sensing and signaling.

Epithelial delamination is protective during pharmaceutical-induced enteropathy.

Intestinal epithelial cell (IEC) shedding is a fundamental response to intestinal damage, yet underlying mechanisms and functions have been difficult to define. Here we model chronic intestinal damage in zebrafish larvae using the nonsteroidal antiinflammatory drug (NSAID) Glafenine. Glafenine induced the unfolded protein response (UPR) and inflammatory pathways in IECs, leading to delamination. Glafenine-induced inflammation was augmented by microbial colonization and associated with changes in intestinal and environmental microbiotas. IEC shedding was a UPR-dependent protective response to Glafenine that restricts inflammation and promotes animal survival. Other NSAIDs did not induce IEC delamination; however, Glafenine also displays off-target inhibition of multidrug resistance (MDR) efflux pumps. We found a subset of MDR inhibitors also induced IEC delamination, implicating MDR efflux pumps as cellular targets underlying Glafenine-induced enteropathy. These results implicate IEC delamination as a protective UPR-mediated response to chemical injury, and uncover an essential role for MDR efflux pumps in intestinal homeostasis.

Intestinal Serum amyloid A suppresses systemic neutrophil activation and bactericidal activity in response to microbiota colonization.

The intestinal microbiota influences the development and function of myeloid lineages such as neutrophils, but the underlying molecular mechanisms are unresolved. Using gnotobiotic zebrafish, we identified the immune effector Serum amyloid A (Saa) as one of the most highly induced transcripts in digestive tissues following microbiota colonization. Saa is a conserved secreted protein produced in the intestine and liver with described effects on neutrophils in vitro, however its in vivo functions remain poorly defined. We engineered saa mutant zebrafish to test requirements for Saa on innate immunity in vivo. Zebrafish mutant for saa displayed impaired neutrophil responses to wounding but augmented clearance of pathogenic bacteria. At baseline, saa mutants exhibited moderate neutrophilia and altered neutrophil tissue distribution. Molecular and functional analyses of isolated neutrophils revealed that Saa suppresses expression of pro-inflammatory markers and bactericidal activity. Saa's effects on neutrophils depended on microbiota colonization, suggesting this protein mediates the microbiota's effects on host innate immunity. To test tissue-specific roles of Saa on neutrophil function, we over-expressed saa in the intestine or liver and found that sufficient to partially complement neutrophil phenotypes observed in saa mutants. These results indicate Saa produced by the intestine in response to microbiota serves as a systemic signal to neutrophils to restrict aberrant activation, decreasing inflammatory tone and bacterial killing potential while simultaneously enhancing their ability to migrate to wounds.

Microbiota of Inflammatory Bowel Disease Models.

Gut microbiome plays an important role in inflammatory bowel disease (IBD), a group of intestinal chronic inflammation conditions that affect a large population. The animal models of IBD have long been established on basis of pathological features, but their ability to recapitulate patient gut microbiota is unknown. We investigated and compared the composition and biodiversity of bacterial population in the fecal samples from rat models of the two IBD subtypes, and compared them with patient samples. Our analyses revealed that inflammation reduces overall microbiome diversity and increased variation between individuals. We identified specific microbial signatures associated with the two IBD subtypes that were consistent between the animal models and human IBD patients, suggesting that the animal models can partially recapitulate the microbiota in human diseases. Furthermore, metagenome prediction analysis suggested microbial functions that were likely altered by host-microbiota interactions in IBD models.

Antibacterial soap use impacts skin microbial communities in rural Madagascar.

The skin harbors diverse communities of microorganisms, and alterations to these communities can impact the effectiveness of the skin as a barrier to infectious organisms or injury. As the global availability and adoption of antibacterial products increases, it is important to understand how these products affect skin microbial communities of people living in rural areas of developing countries, where risks of infection and injury often differ from urban populations in developed countries. We investigated the effect of antibacterial soap on skin microbial communities in a rural Malagasy population that practices subsistence agriculture in the absence of electricity and running water. We quantified the amount of soap used by each participant and obtained skin swab samples at three time points: prior to soap use, immediately after one week of soap use, and two weeks after soap use was discontinued. Soap use did not significantly impact ecological measures of diversity and richness (alpha diversity). However, the amount of soap used was a predictor of community-level change (beta diversity), with changes persisting for at least two weeks after subjects stopped using soap. Our results indicate that the overall species richness of skin microbial communities may be resistant to short-term use of antibacterial soap in settings characterized by regular contact with the natural environment, yet these communities may undergo shifts in microbial composition. Lifestyle changes associated with the use of antibacterial soap may therefore cause rapid alterations in skin microbial communities, with the potential for effects on skin health.

Environmental influences on the skin microbiome of humans and cattle in rural Madagascar.

BACKGROUND AND OBJECTIVES: The skin harbors a dynamic community of microorganisms, where contact with humans, other animals and the environment can alter microbial communities. Most research on the human skin microbiome features Western populations living in hygienic conditions, yet these populations have vastly different patterns of environmental contact than the majority of people on Earth, including those living in developing countries. METHODOLOGY: We studied skin microbial communities of humans and cattle (zebu) in rural Madagascar to investigate how zebu ownership affects microbial composition of the human skin, and to characterize non-Western human and zebu skin communities more generally. A portion of the 16S rRNA gene was sequenced from samples of zebu backs and human ankles, forearms, hands and armpits. Analyses were conducted in QIIME, R and LEfSe. RESULTS: Human and zebu samples varied in microbial community composition, yet we did not find evidence for a shared microbial signature between an individual and his zebu. Microbial communities differed across human body sites, with ankles reflecting increased diversity and greater similarity to samples from zebu, likely due to extensive shared contact with soil by humans and zebu. CONCLUSIONS AND IMPLICATIONS: Cattle ownership had, at best, weak effects on the human skin microbiome. We suggest that components of human biology and lifestyles override the microbial signature of close contact with zebu, including genetic factors and human-human interaction, irrespective of zebu ownership. Understanding ecological drivers of microbial communities will help determine ways that microbial transfer and community composition change as populations adopt Western lifestyles, and could provide insights into zoonotic disease transmission.

Conserved genomic collinearity as a source of broadly applicable, fast evolving, markers to resolve species complexes: A case study using the lichen-forming genus Peltigera section Polydactylon.

Synteny can be maintained for certain genomic regions across broad phylogenetic groups. In these homologous genomic regions, sites that are under relaxed purifying selection, such as intergenic regions, could be used broadly as markers for population genetic and phylogenetic studies on species complexes. To explore the potential of this approach, we found 125 Collinear Orthologous Regions (COR) ranging from 1 to >10kb across nine genomes representing the Lecanoromycetes and Eurotiomycetes (Pezizomycotina, Ascomycota). Twenty-six of these COR were found in all 24 eurotiomycete genomes surveyed for this study. Given the high abundance and availability of fungal genomes we believe this approach could be adopted for other large groups of fungi outside the Pezizomycotina. Asa proof of concept, we selected three Collinear Orthologous Regions (COR1b, COR3, and COR16), based on synteny analyses of several genomes representing three classes of Ascomycota: Eurotiomycetes, Lecanoromycetes, and Lichinomycetes. COR16, for example, was found across these three classes of fungi. Here we compare the resolving power of these three new markers with five loci commonly used in phylogenetic studies of fungi, using section Polydactylon of the cyanolichen-forming genus Peltigera (Lecanoromycetes) - a clade with several challenging species complexes. Sequence data were subjected to three species discovery and two validating methods. COR markers substantially increased phylogenetic resolution and confidence, and highly contributed to species delimitation. The level of phylogenetic signal provided by each of the COR markers was higher than the commonly used fungal barcode ITS. High cryptic diversity was revealed by all methods. As redefined here, most species represent lineages that have relatively narrower, and more homogeneous biogeographical ranges than previously understood. The scabrosoid clade consists of ten species, seven of which are new. For the dolichorhizoid clade, twenty-two new species were discovered for a total of twenty-nine species in this clade.

Genomic sequencing-based mutational enrichment analysis identifies motility genes in a genetically intractable gut microbe.

A major roadblock to understanding how microbes in the gastrointestinal tract colonize and influence the physiology of their hosts is our inability to genetically manipulate new bacterial species and experimentally assess the function of their genes. We describe the application of population-based genomic sequencing after chemical mutagenesis to map bacterial genes responsible for motility in Exiguobacterium acetylicum, a representative intestinal Firmicutes bacterium that is intractable to molecular genetic manipulation. We derived strong associations between mutations in 57 E. acetylicum genes and impaired motility. Surprisingly, less than half of these genes were annotated as motility-related based on sequence homologies. We confirmed the genetic link between individual mutations and loss of motility for several of these genes by performing a large-scale analysis of spontaneous suppressor mutations. In the process, we reannotated genes belonging to a broad family of diguanylate cyclases and phosphodiesterases to highlight their specific role in motility and assigned functions to uncharacterized genes. Furthermore, we generated isogenic strains that allowed us to establish that Exiguobacterium motility is important for the colonization of its vertebrate host. These results indicate that genetic dissection of a complex trait, functional annotation of new genes, and the generation of mutant strains to define the role of genes in complex environments can be accomplished in bacteria without the development of species-specific molecular genetic tools.

The severity of nonalcoholic fatty liver disease is associated with gut dysbiosis and shift in the metabolic function of the gut microbiota.

UNLABELLED: Several animal studies have emphasized the role of gut microbiota in nonalcoholic fatty liver disease (NAFLD). However, data about gut dysbiosis in human NAFLD remain scarce in the literature, especially studies including the whole spectrum of NAFLD lesions. We aimed to evaluate the association between gut dysbiosis and severe NAFLD lesions, that is, nonalcoholic steatohepatitis (NASH) and fibrosis, in a well-characterized population of adult NAFLD. Fifty-seven patients with biopsy-proven NAFLD were enrolled. Taxonomic composition of gut microbiota was determined using 16S ribosomal RNA gene sequencing of stool samples. Thirty patients had F0/F1 fibrosis stage at liver biopsy (10 with NASH), and 27 patients had significant F≥2 fibrosis (25 with NASH). Bacteroides abundance was significantly increased in NASH and F≥2 patients, whereas Prevotella abundance was decreased. Ruminococcus abundance was significantly higher in F≥2 patients. By multivariate analysis, Bacteroides abundance was independently associated with NASH and Ruminococcus with F≥2 fibrosis. Stratification according to the abundance of these two bacteria generated three patient subgroups with increasing severity of NAFLD lesions. Based on imputed metagenomic profiles, Kyoto Encyclopedia of Genes and Genomes pathways significantly related to NASH and fibrosis F≥2 were mostly related to carbohydrate, lipid, and amino acid metabolism. CONCLUSION: NAFLD severity associates with gut dysbiosis and a shift in metabolic function of the gut microbiota. We identified Bacteroides as independently associated with NASH and Ruminococcus with significant fibrosis. Thus, gut microbiota analysis adds information to classical predictors of NAFLD severity and suggests novel metabolic targets for pre-/probiotics therapies.

Factors Affecting the Uptake of HIV Testing among Men: A Mixed-Methods Study in Rural Burkina Faso.

BACKGROUND: This study aimed to explore factors shaping the decision to undergo Human Immunodeficiency Virus (HIV) testing among men in rural Burkina Faso. METHODS: The study took place in 2009 in the Nouna Health District and adopted a triangulation mixed methods design. The quantitative component relied on data collected through a structured survey on a representative sample of 1130 households. The qualitative component relied on 38 in-depth interviews, with men purposely selected to represent variation in testing decision, age, and place of residence. A two-part model was conducted, with two distinct outcome variables, i.e. "being offered an HIV test" and "having done an HIV test". The qualitative data analysis relied on inductive coding conducted by three independent analysts. RESULT: Of the 937 men, 357 had been offered an HIV test and 97 had taken the test. Younger age, household wealth, living in a village under demographic surveillance, and knowing that HIV testing is available at primary health facilities were all positively associated with the probability of being offered an HIV test. Household wealth and literacy were found to be positively associated, and distance was found to be negatively associated with the probability of having taken an HIV test. Qualitative findings indicated that the limited uptake of HIV testing was linked to poor knowledge on service availability and to low risk perceptions. CONCLUSION: With only 10% of the total sample ever having tested for HIV, our study confirmed that male HIV testing remains unacceptably low in Sub-Saharan Africa. This results from a combination of health system factors, indicating general barriers to access, and motivational factors, such as one's own knowledge of service availability and risk perceptions. Our findings suggested that using antenatal care and curative services as the exclusive entry points into HIV testing may not be sufficient to reach large portions of the male population. Thus, additional strategies are urgently needed to increase service uptake.

Evaluation of the integrated disease surveillance and response system for infectious diseases control in northern Ghana.

BACKGROUND: Well-functioning surveillance systems are crucial for effective disease control programs. The Integrated Disease Surveillance and Response (IDSR) strategy was developed and adopted in 1998 for Africa as a comprehensive public health approach and subsequently, Ghana adopted the IDSR technical guidelines in 2002. Since 2012, the IDSR data is reported through the new District Health Information Management System II (DHIMS2) network. The objective was to evaluate the Integrated Disease Surveillance and Response (IDSR) system in northern Ghana. METHODS: This was an observational study using mixed methods. Weekly and monthly IDSR data on selected infectious diseases were downloaded and analyzed for 2011, 2012 and 2013 (the years before, of and after DHIMS2 implementation) from the DHIMS2 databank for the Upper East Region (UER) and for two districts of UER. In addition, key informant interviews were conducted among local and regional health officers on the functioning of the IDSR. RESULTS: Clinically diagnosed malaria was the most prevalent disease in UER, with an annual incidence rate close to 1. Around 500 suspected HIV/AIDS cases were reported each year. The highest incidence of cholera and meningitis was reported in 2012 (257 and 392 cases respectively). Three suspected cases of polio and one suspected case of guinea worm were reported in 2013. None of the polio and guinea worm cases and only a fraction of the reported cases of the other diseases were confirmed. A major observation was the large and inconclusive difference in reported cases when comparing weekly and monthly reports. This can be explained by the different reporting practice for the sub-systems. Other challenges were low priority for surveillance, ill-equipped laboratories, rare supervision and missing feedback. CONCLUSIONS: The DHIMS2 has improved the availability of IDSR reports, but the quality of data reported is not sufficient. Particularly the inconsistencies between weekly and monthly data need to be addressed. Moreover, support for and communication within the IDSR system is inadequate and calls for attention.

Unisexual reproduction of Cryptococcus gattii.

Cryptococcus gattii is a basidiomycetous human fungal pathogen that typically causes infection in tropical and subtropical regions and is responsible for an ongoing outbreak in immunocompetent individuals on Vancouver Island and in the Pacific Northwest of the US. Pathogenesis of this species may be linked to its sexual cycle that generates infectious propagules called basidiospores. A marked predominance of only one mating type (α) in clinical and environmental isolates suggests that a-α opposite-sex reproduction may be infrequent or geographically restricted, raising the possibility of an alternative unisexual cycle involving cells of only α mating type, as discovered previously in the related pathogenic species Cryptococcus neoformans. Here we report observation of hallmark features of unisexual reproduction in a clinical isolate of C. gattii (isolate 97/433) and describe genetic and environmental factors conducive to this sexual cycle. Our results are consistent with population genetic evidence of recombination in the largely unisexual populations of C. gattii and provide a useful genetic model for understanding how novel modes of sexual reproduction may contribute to evolution and virulence in this species.

Transmission of Hypervirulence traits via sexual reproduction within and between lineages of the human fungal pathogen cryptococcus gattii.

Since 1999 a lineage of the pathogen Cryptococcus gattii has been infecting humans and other animals in Canada and the Pacific Northwest of the USA. It is now the largest outbreak of a life-threatening fungal infection in a healthy population in recorded history. The high virulence of outbreak strains is closely linked to the ability of the pathogen to undergo rapid mitochondrial tubularisation and proliferation following engulfment by host phagocytes. Most outbreaks spread by geographic expansion across suitable niches, but it is known that genetic re-assortment and hybridisation can also lead to rapid range and host expansion. In the context of C. gattii, however, the likelihood of virulence traits associated with the outbreak lineages spreading to other lineages via genetic exchange is currently unknown. Here we address this question by conducting outgroup crosses between distantly related C. gattii lineages (VGII and VGIII) and ingroup crosses between isolates from the same molecular type (VGII). Systematic phenotypic characterisation shows that virulence traits are transmitted to outgroups infrequently, but readily inherited during ingroup crosses. In addition, we observed higher levels of biparental (as opposed to uniparental) mitochondrial inheritance during VGII ingroup sexual mating in this species and provide evidence for mitochondrial recombination following mating. Taken together, our data suggest that hypervirulence can spread among the C. gattii lineages VGII and VGIII, potentially creating novel hypervirulent genotypes, and that current models of uniparental mitochondrial inheritance in the Cryptococcus genus may not be universal.