Malaria remains a major health problem in the world. It is a neglected disease because it occurs almost exclusively in poor developing countries, which offer negligible marketable and profitable opportunities. Malaria...Malaria remains a major health problem in the world. It is a neglected disease because it occurs almost exclusively in poor developing countries, which offer negligible marketable and profitable opportunities. Malaria(together with Tuberculosis), is responsible for an unprecedented global health crisis with devastating effects in developing countries. The 2011 Word Malaria Report indicated that 106 countries showed endemic malaria. Malaria control depends mainly on drug treatment, which is increasingly difficult due to the spread of drug resistant parasites and requires expensive drug combinations. Part of the inability to combat this disease is attributed to an incomplete understanding of its pathogenesis and pathophysiology. Improving the knowledge of the underlying pathogenic mechanisms of malaria transmission and of the exclusive metabolic pathways of the parasites(protozoa of the genus Plasmodium), should promote efficient treatment of disease and help the identification of novel targets for potential therapeutic interventions. Moreover, the elucidation of determinants involved in the spread of malaria will provide important information for efficient planning of strategies for targeted control.展开更多
The use of genetically modified mosquitoes to reduce or replace field populations is a new strategy to control mosquito-borne diseases. The precondition of the implementation of this strategy is the ability to manipul...The use of genetically modified mosquitoes to reduce or replace field populations is a new strategy to control mosquito-borne diseases. The precondition of the implementation of this strategy is the ability to manipulate the genome of mosquitoes and to induce specific expression of the effector molecules driven by a suitable promoter. The objective of this study is to evaluate the expression of defensin A gene of Anopheles sinensis under the control of a vitellogenin promoter in transgenic Anopheles ste- phensi. The regulatory region of Anopheles gambiae vitellogenin was cloned and subcloned into transfer vector pSLFa consisting of an expression cassette with defensin A coding sequence. Then, the expression cassette was transferred into transformation vector pBac[3xP3-DsRedafm] using Asc I di- gestion. The recombinant plasmid DNA of pBac[3xP3DsRed-AgVgT2-DefA] and helper plasmid DNA of phsp-pBac were micro-injected into embryos of An. stephensi. The positive transgenic mosquitoes were screened by observing specific red fluorescence in the eyes of G1 larvae. Southern blot analysis showed that a single-copy transgene integrated into the genome of An. stephensi. RT-PCR analysis showed that the defensin A gene expressed specifically in fat bodies of female mosquitoes after a blood meal. Interestingly, the mRNA of defensin A is more stable compared with that of the endogenous vitellogenin gene. After multiple blood meals, the expression of defensin A appeared as a reducible and non-cycling type, a crucial feature for its anti-pathogen effect. From data above, we concluded that the regulatory function of the Vg promoter and the expression of defensin A gene were relatively con- served in different species of anopheles mosquitoes. These molecules could be used as candidates in the development of genetically modified mosquitoes.展开更多
This study describes the bio-ecology of local Anopheles vectors, their abundance, type and vectoral competence in three communities around Kumasi Metropolis. The study sites were selected based on bio-ecologic zones ...This study describes the bio-ecology of local Anopheles vectors, their abundance, type and vectoral competence in three communities around Kumasi Metropolis. The study sites were selected based on bio-ecologic zones （urban, peri-urban and rural） which influence habitat and behavior. Pyrethrum spray catch was used in the collection of indoor resting mosquitoes from bedrooms of study communities （June-August 2008）. The identification of mosquitoes was based on morphological keys earlier described. The blood meal taken and the stage of digestion and egg development were also observed. A total of 293 mosquitoes were collected and 50.5% were A. gambiae s.I. Of the three bio-ecologic zones： urban, 53.4% were A. gambiae s.l, 27.2% Culex and 19.4% Mansonia; peri-urban, 58% A. gambiae s. 1 and 42% Culex pipien s. 1 and rural, 40.2% A. gambiae s. 1, and 58.8% Culex sp respectively. About 96.6% of all mosquitoes collected had taken blood meals, with 50% of these being Anopheles gambiae s.I. Our findings indicate that urban rather exhibits rural characteristics and can best be described as ＂urban poor＂. However, more data need to be collected to ascertain this. The anopheline mosquitoes in the study communities are highly endophillic and anthropophagic and thus have high vectoral competence. The authors recommend frequent mosquito surveillance to avert malaria epidemic.展开更多
Background:Irrigated agriculture is key to increase agricultural productivity and ensure food security in Africa.However,unintended negative public health impacts(e.g.malaria)of such environmental modification have be...Background:Irrigated agriculture is key to increase agricultural productivity and ensure food security in Africa.However,unintended negative public health impacts(e.g.malaria)of such environmental modification have been a challenge.This study assessed the diversity and distribution of breeding habitats of malaria vector mosquitoes around Arjo-Dedessa irrigation development site in Southwest Ethiopia.Methods:Anopheline mosquito larvae were surveyed from two agroecosystems,‘irrigated’and‘non-irrigated’areas during the dry(December 2017–February 2018)and wet(June 2018–August 2018)seasons.Mosquito habitat diversity and larval abundance were compared between the irrigated and non-irrigated areas.The association between anopheline mosquito larvae occurrence and environmental parameters was analysed using Pearson chisquare.Multiple logistic regression analysis was used to determine primary parameters that influence the occurrence of anopheline larvae.Results:Overall,319 aquatic habitats were surveyed during the study period.Around 60%(n=152)of the habitats were positive for anopheline mosquito larvae,of which 63.8%(n=97)and 36.2%(n=55)were from irrigated and non-irrigated areas,respectively.The number of anopheline positive habitats was two-fold higher in irrigated than non-irrigated areas.Anopheline larval abundance in the irrigated area was 16.6%higher than the non-irrigated area.Pearson’s chi-square analysis showed that season(χ2=63.122,df=1,P<0.001),agroecosystem(being irrigated or non-irrigated)(χ2=6.448,df=1,P=0.011),and turbidity(χ2=7.296,df=2,P=0.025)had a significant association with larval anopheline occurrence.Conclusions:The study showed a higher anopheline mosquito breeding habitat diversity,larval occurrence and abundance in the irrigated than non-irrigated areas in both dry and wet seasons.This indicates that irrigation development activities contribute to proliferation of suitable mosquito breeding habitats that could increase the risk of malaria transmission.Incorporating larval source 展开更多
文摘Malaria remains a major health problem in the world. It is a neglected disease because it occurs almost exclusively in poor developing countries, which offer negligible marketable and profitable opportunities. Malaria(together with Tuberculosis), is responsible for an unprecedented global health crisis with devastating effects in developing countries. The 2011 Word Malaria Report indicated that 106 countries showed endemic malaria. Malaria control depends mainly on drug treatment, which is increasingly difficult due to the spread of drug resistant parasites and requires expensive drug combinations. Part of the inability to combat this disease is attributed to an incomplete understanding of its pathogenesis and pathophysiology. Improving the knowledge of the underlying pathogenic mechanisms of malaria transmission and of the exclusive metabolic pathways of the parasites(protozoa of the genus Plasmodium), should promote efficient treatment of disease and help the identification of novel targets for potential therapeutic interventions. Moreover, the elucidation of determinants involved in the spread of malaria will provide important information for efficient planning of strategies for targeted control.
基金Supported by the National Natural Science Foundation of China (Grant No. 30271162)the Chinese Scholarship Council (Grant No. 2003365035)
文摘The use of genetically modified mosquitoes to reduce or replace field populations is a new strategy to control mosquito-borne diseases. The precondition of the implementation of this strategy is the ability to manipulate the genome of mosquitoes and to induce specific expression of the effector molecules driven by a suitable promoter. The objective of this study is to evaluate the expression of defensin A gene of Anopheles sinensis under the control of a vitellogenin promoter in transgenic Anopheles ste- phensi. The regulatory region of Anopheles gambiae vitellogenin was cloned and subcloned into transfer vector pSLFa consisting of an expression cassette with defensin A coding sequence. Then, the expression cassette was transferred into transformation vector pBac[3xP3-DsRedafm] using Asc I di- gestion. The recombinant plasmid DNA of pBac[3xP3DsRed-AgVgT2-DefA] and helper plasmid DNA of phsp-pBac were micro-injected into embryos of An. stephensi. The positive transgenic mosquitoes were screened by observing specific red fluorescence in the eyes of G1 larvae. Southern blot analysis showed that a single-copy transgene integrated into the genome of An. stephensi. RT-PCR analysis showed that the defensin A gene expressed specifically in fat bodies of female mosquitoes after a blood meal. Interestingly, the mRNA of defensin A is more stable compared with that of the endogenous vitellogenin gene. After multiple blood meals, the expression of defensin A appeared as a reducible and non-cycling type, a crucial feature for its anti-pathogen effect. From data above, we concluded that the regulatory function of the Vg promoter and the expression of defensin A gene were relatively con- served in different species of anopheles mosquitoes. These molecules could be used as candidates in the development of genetically modified mosquitoes.
文摘This study describes the bio-ecology of local Anopheles vectors, their abundance, type and vectoral competence in three communities around Kumasi Metropolis. The study sites were selected based on bio-ecologic zones （urban, peri-urban and rural） which influence habitat and behavior. Pyrethrum spray catch was used in the collection of indoor resting mosquitoes from bedrooms of study communities （June-August 2008）. The identification of mosquitoes was based on morphological keys earlier described. The blood meal taken and the stage of digestion and egg development were also observed. A total of 293 mosquitoes were collected and 50.5% were A. gambiae s.I. Of the three bio-ecologic zones： urban, 53.4% were A. gambiae s.l, 27.2% Culex and 19.4% Mansonia; peri-urban, 58% A. gambiae s. 1 and 42% Culex pipien s. 1 and rural, 40.2% A. gambiae s. 1, and 58.8% Culex sp respectively. About 96.6% of all mosquitoes collected had taken blood meals, with 50% of these being Anopheles gambiae s.I. Our findings indicate that urban rather exhibits rural characteristics and can best be described as ＂urban poor＂. However, more data need to be collected to ascertain this. The anopheline mosquitoes in the study communities are highly endophillic and anthropophagic and thus have high vectoral competence. The authors recommend frequent mosquito surveillance to avert malaria epidemic.
基金This study was supported by grants from the National Institutes of Health(D43 TW001505,R01 A1050243 and U19 AI129326).
文摘Background:Irrigated agriculture is key to increase agricultural productivity and ensure food security in Africa.However,unintended negative public health impacts(e.g.malaria)of such environmental modification have been a challenge.This study assessed the diversity and distribution of breeding habitats of malaria vector mosquitoes around Arjo-Dedessa irrigation development site in Southwest Ethiopia.Methods:Anopheline mosquito larvae were surveyed from two agroecosystems,‘irrigated’and‘non-irrigated’areas during the dry(December 2017–February 2018)and wet(June 2018–August 2018)seasons.Mosquito habitat diversity and larval abundance were compared between the irrigated and non-irrigated areas.The association between anopheline mosquito larvae occurrence and environmental parameters was analysed using Pearson chisquare.Multiple logistic regression analysis was used to determine primary parameters that influence the occurrence of anopheline larvae.Results:Overall,319 aquatic habitats were surveyed during the study period.Around 60%(n=152)of the habitats were positive for anopheline mosquito larvae,of which 63.8%(n=97)and 36.2%(n=55)were from irrigated and non-irrigated areas,respectively.The number of anopheline positive habitats was two-fold higher in irrigated than non-irrigated areas.Anopheline larval abundance in the irrigated area was 16.6%higher than the non-irrigated area.Pearson’s chi-square analysis showed that season(χ2=63.122,df=1,P<0.001),agroecosystem(being irrigated or non-irrigated)(χ2=6.448,df=1,P=0.011),and turbidity(χ2=7.296,df=2,P=0.025)had a significant association with larval anopheline occurrence.Conclusions:The study showed a higher anopheline mosquito breeding habitat diversity,larval occurrence and abundance in the irrigated than non-irrigated areas in both dry and wet seasons.This indicates that irrigation development activities contribute to proliferation of suitable mosquito breeding habitats that could increase the risk of malaria transmission.Incorporating larval source
