Polykystose renale autosomique dominante (PKAD) au CNHU-HKM de Cotonou: profil épidémiologique, clinique, biologique et intérêt du dépistage familial

Introduction: Étudier le profil épidémiologique, clinique et paraclinique de la PKAD chez des patients diagnostiqués au CNHU de Cotonou et évaluer l'intérêt d'un dépistage chez les patients à risque. Méthodes: Il s'agit d'une étude transversale comportant une revue de dossiers des patients  cliniquement diagnostiqués PKAD à la clinique universitaire de néphrologie et d'hémodialyse du 1er janvier 2000 au 31 janvier 2011, et une enquête familiale chez les patients où le diagnostic de PKAD a été confirmé entre le 1er février et le 31 Août 2011.Un séquençage à la recherche de mutations dans les gènes de la Polycystine 1 et 2 a été réalisé chez les cas index. Résultats: L'incidence hospitalière de la PKAD était de 7,8 cas par an. Le dépistage familial avait permis d'examiner 99 membres de 22 familles et de confirmer 14 cas de PKAD. L'âge moyen des patients était de 45,6±12,8ans. Le signe physique le plus fréquent était l'hypertension artérielle (HTA (83%). Une  insuffisance rénale chronique était observée dans 75% des cas. Le séquençage direct avait permis de mettre en évidence 7 nouvelles mutations dont 02 mutations dans les gènes PKD2 et 5 dans PKD1. Conclusion: La PKAD relativement fréquente, présente de nouvelles mutations chez les patients  diagnostiqués au CNHU de Cotonou. Le conseil génétique est particulièrement indiqué dans les familles où la maladie rénale a débuté précocement.Key words: Polykystose rénale autosomique dominante, dépistage, mutations PKD2 et PKD

Molecular detection and differentiation of Brazilian and African isolates of the entomopathogen Neozygites tanajoae (Entomophthorales: Neozygitaceae) with PCR using specific primers

Neozygites tanajoae is an entomopathogenic fungus which has been used for biocontrol of the cassava green mite (Mononychellus tanajoa, CGM) in Africa. Establishment and dispersal of Brazilian isolates which have been introduced into some African countries in recent years to improve CGM control was followed with specific PCR assays. Two primer pairs, NEOSSU_F/NEOSSU_R and 8DDC_F/8DDC_R, were used to differentiate isolates collected from several locations in Brazil and from three countries in Africa, Benin, Ghana and Tanzania. The first primer pair enabled the species-specific detection of Neozygites tanajoae, while the second differentiated the Brazilian isolates from those of other geographical origin. PCR assays were designed for detection of fungal DNA in the matrix of dead infested mites since N. tanajoae is difficult to isolate and culture on selective artificial media. Our results show that all isolates (Brazilian and African) that sporulated on mummified mites were amplified with the first primer pair confirming their Neozygites tanajoae identity. The second pair amplified DNA from all the Brazilian isolates, but did not amplify any DNA samples from the African isolates. None of the two primers showed amplification neither from any of the non-sporulating mite extracts nor from the dead uninfected mites used as negative controls. We confirmed that the two primer pairs tested are suitable for the detection and differential identification of N. tanajoae isolates from Brazil and Africa and that they are useful to monitor the establishment and spread of the Brazilian isolates of N. tanajoae introduced into Benin or into other African countries for improvement of CGM biocontrol.Deutscher Akademischer Austauschdienst (DAAD) fellowshipInternational Institute of Tropical Agriculture (IITA) through a field work grant from the International Fund for Agricultural Development (IFAD)University of Goettingen in German

Scaling up tests on virulence of the cassava green mite fungal pathogen Neozygites tanajoae (Entomophthorales: Neozygitaceae) under controlled conditions: first observations at the population level

Virulence of entomopathogens is often measured at the individual level using a single host individual or a group of host individuals. To what extent these virulence assessments reflect the impact of an entomopathogen on their host in the field remains largely untested, however. A methodology was developed to induce epizootics of the cassava green mite fungal pathogen Neozygites tanajoae under controlled conditions to evaluate population-level virulence of two (one Beninese and one Brazilian) isolates of the entomopathogen-which had shown similar individual-level virulence but different field impacts. In unrepeated separate experiments we inoculated mite-infested potted cassava plants with either 50 or 25 live mites (high and low inoculum) previously exposed to spores of N. tanajoae and monitored the development of fungal infections for each isolate under the same conditions. Both isolates caused mite infections and an associated decline in host mite populations relative to the control (without fungus) in all experiments, but prevalence of the fungus varied with isolate and increased with inoculum density. Peak infection levels were 90% for the Beninese isolate and 36% for the Brazilian isolate at high inoculum density, and respectively 17% and 25% at low inoculum density. We also measured dispersal from inoculated plants and found that spore dispersal increased with host infection levels, independent of host densities, whereas mite dispersal varied between isolates. These results demonstrate that epizootiology of N. tanajoae can be studied under controlled conditions and suggest that virulence tests at the population level may help to better predict performance of fungal isolates than individual-level tests