scholarly journals Bacterial Biodiversity in Midguts of Anopheles Mosquitoes, Malaria Vectors in Southeast Asia

10.5772/55610 ◽  
2013 ◽  
Author(s):  
Sylvie Manguin ◽  
Chung Thuy Ngo ◽  
Krajana Tainchum ◽  
Waraporn Juntarajumnong ◽  
Theeraphap Chareonviriyaphap ◽  
...  
Keyword(s):  
Southeast Asia ◽  
Malaria Vectors ◽  
Anopheles Mosquitoes ◽  
Bacterial Biodiversity

scholarly journals Salivary complement inhibitors from mosquitoes: Structure and mechanism of action

2020 ◽  
pp. jbc.RA120.015230
Author(s):  
Ethan C Strayer ◽  
Stephen Lu ◽  
Jose M. Ribeiro ◽  
John F. Andersen
Keyword(s):  
Functional Role ◽  
Alternative Pathway ◽  
Malaria Vectors ◽  
Salivary Proteins ◽  
Plasma Extravasation ◽  
Lower Affinity ◽  
Anopheles Mosquitoes ◽  
Highly Active ◽  
Complement Inhibitors ◽  
Insight Into

Inhibition of the alternative pathway (AP) of complement by saliva from Anopheles mosquitoes facilitates feeding by blocking production of the anaphylatoxins C3a and C5a which activate mast cells leading to plasma extravasation, pain and itching. We have previously shown that albicin, a member of the SG7 protein family from An. albimanus blocks the AP by binding to and inhibiting the function of the C3 convertase, C3bBb. Here we show that SG7.AF, the albicin homolog from An. freeborni, has a similar potency to albicin but is more active in the presence of properdin, a plasma protein that acts to stabilize C3bBb. Conversely, albicin is highly active in the absence or presence of properdin. Albicin and SG7.AF stabilize the C3bBb complex in a form that accumulates on surface plasmon resonance (SPR) surfaces coated with properdin but SG7.AF binds with lower affinity than albicin. Albicin induces oligomerization of the complex in solution, suggesting that it is oligomerization that leads to stabilization on SPR surfaces. Anophensin, the albicin ortholog from An. stephensi, is only weakly active as an inhibitor of the AP, suggesting that the SG7 family may play a different functional role in this species and other species of the subgenus Cellia, containing the major malaria vectors in Africa and Asia. Crystal structures of albicin and SG7.AF reveal a novel four-helix bundle arrangement, that is stabilized by a N-terminal hydrogen bonding network. These structures provide insight into the SG7 family and related mosquito salivary proteins including the platelet-inhibitory 30kDa family.

scholarly journals Molecular detection and maternal transmission of a bacterial symbiont Asaia species in field-caught Anopheles mosquitoes from Cameroon

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Claudine Grâce Tatsinkou Maffo ◽  
Maurice Marcel Sandeu ◽  
Amen Nakebang Fadel ◽  
Magellan Tchouakui ◽  
Daniel Nguiffo Nguete ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Nucleotide Sequence ◽  
Mosquito Species ◽  
Sub Saharan Africa ◽  
Malaria Vectors ◽  
Infection Prevalence ◽  
Sequence Variant ◽  
Maternal Transmission ◽  
Anopheles Mosquitoes ◽  
Low Genetic Diversity

Abstract Background Malaria control relies mainlyon insecticide-based tools. However, the effectiveness of these tools is threatened by widespread insecticide resistance in malaria vectors, highlighting the need for alternative control approaches. The endosymbiont Asaia has emerged as a promising candidate for paratransgenic control of malaria, but its biology and genetics still need to be further analyzed across Africa. Here, we investigated the prevalence of Asaia and its maternal transmission in the natural population of Anopheles mosquitoes in Cameroon. Methods Indoor-resting adult mosquitoes belonging to four species (An. coluzzii, An. arabiensis, An. funestus and An. gambiae) were collected from eight localities across Cameroon from July 2016 to February 2020. PCR was performed on the Asaia-specific 16S ribosomal RNA gene, and samples positive by PCR for Asaia were confirmed by Sanger sequencing and phylogenetic analysis. The vertical transmission of Asaia was investigated by screening F1 mosquitoes belonging to F0Asaia-positive females. Results A total of 895 mosquitoes were screened. We found 43% (384) Asaia infection prevalence in four mosquito species. Phylogenetic analysis revealed that Asaia from Cameroon clustered together with the strains of Asaia isolated from other parts of the world. In addition, seven nucleotide sequence variants were found with low genetic diversity (π = 0.00241) and nucleotide sequence variant diversity (Hd = 0.481). Asaia was vertically transmitted with high frequency (range from 42.5 to 100%). Conclusions This study provides field-based evidence of the presence of Asaia in Anopheles mosquitoes in Cameroon for exploitation as a symbiont in the control of malaria in sub-Saharan Africa. Graphical abstract

scholarly journals Utility of Complete Mitochondrial Genomes in Phylogenetic Classification of the Species of Anopheles (Culicidae: Anophelinae)

2021 ◽  
Author(s):  
Taghi Ghassemi-Khademi ◽  
Mohammad Ali Oshaghi ◽  
Hassan Vatandoost ◽  
Seyed Massoud Madjdzadeh ◽  
Mohammad Amin Gorouhi
Keyword(s):  
Evolutionary Biology ◽  
Phylogenetic Trees ◽  
Complete Mitochondrial Genome ◽  
Malaria Vectors ◽  
Mitochondrial Genomes ◽  
Phylogenetic Classification ◽  
Anopheles Mosquitoes ◽  
Blood Sucking ◽  
Complete Mitochondrial Genomes

Background: Among the blood-sucking insects, Anopheles mosquitoes have a very special position, because they transmit parasites of the genus Plasmodium, which cause malaria as one of the main vector-borne disease worldwide. The aim of this review study was to evaluate utility of complete mitochondrial genomes in phylogenetic classification of the species of Anopheles. Methods: The complete mitochondrial genome sequences belonging to 28 species of the genus Anopheles (n=32) were downloaded from NCBI. The phylogenetic trees were constructed using the ML, NJ, ME, and Bayesian inference methods. Results: In general, the results of the present survey revealed that the complete mitochondrial genomes act very accu- rately in recognition of the taxonomic and phylogenetic status of these species and provide a higher level of support than those based on individual or partial mitochondrial genes so that by using them, we can meticulously reconstruct and modify Anopheles classification. Conclusion: Understanding the taxonomic position of Anopheles, can be a very effective step in better planning for controlling these malaria vectors in the world and will improve our knowledge of their evolutionary biology.

scholarly journals Host-seeking behavior and hourly biting rhythm of vectors in malaria endemic district of Arba Minch area, Southwest Ethiopia

2020 ◽  
Author(s):  
Melkam Abiye Zeru ◽  
Simon Shibru ◽  
Fekadu Massebo
Keyword(s):  
Malaria Vector ◽  
Negative Binomial ◽  
Malaria Vectors ◽  
Malaria Vector Control ◽  
Southwest Ethiopia ◽  
Anopheles Mosquitoes ◽  
Host Seeking ◽  
Human Landing ◽  
Seeking Behavior ◽  
The Impact

Abstract Background The early and outdoor biting behaviors of malaria vectors are among the key challenges in malaria control. Hence, understanding the host-seeking behavior and the peak biting time of malaria vectors is important in malaria vector control programs. This study assessed the host-seeking behavior and hourly biting activity of malaria mosquitoes in Chano Mille village in Arba Minch district, southwest Ethiopia. Methods The first trial was done by keeping cattle together with human that collects the entered mosquitoes in tent, while the other was done by keeping cattle outside a 1 m distance from human collector inside a tent. In both trials, mosquito collation was done inside tents baited by cattle and human using human landing catches (HLC) techniques. Four human volunteers’ were recruited and trained to collect mosquitoes in the four tents from 18:00-24:00 for three months. Two tents were selected randomly for human alone and two for cattle baited collections in the first night and then rotated to minimize the variation due to location of tents and collectors skill. The tent trial was done close to the shore of the Lake Abaya to minimize the interference of other animals on mosquito movement. The peak biting hour of malaria vectors was assessed within a Chano village from 18:00-6:00. Mosquito collation was done both indoor and outdoor by HLC. Morphological speciation of Anopheles mosquitoes was done. The sporozoite infectivity status of Anopheles pharoensis was examined using enzyme-linked immuno-sorbent assay technique. The data was analyzed using a Generalized Estimating Equations with a negative binomial distribution. Results An. pharoensis, An. gambiae complex and An. tenebrosus were the three species documented during the trial. Keeping cattle together with human collector inside the tent attracted 42% ( P < 0.001) more An. pharoensis compared to human alone tent. Also, keeping cattle outside near to a tent with human at 1 m distance, attracted the entering An. pharoensis into the tent inside with human by 46% ( P = 0.002) than human in a tent with no cattle outside the same tent. The impact was not significant for An. gambiae complex and An. tenebrosus. Anopheles pharoensis and An. gambiae complex showed early night biting activity with peak biting from 19.00-20:00 which was significant for both An. gambiae complex ( P < 0.001) and An. pharoensis ( P = 0.015). Anopheles gambiae complex was mainly biting humans outdoor in the village. Conclusions Finally, keeping cattle within and close to human dwellings could increase malaria vectors bite exposure particularly to the zoophilic malaria vector An. pharoensis and, hence deployment of cattle far from human residence could be recommended to reduce the human exposure. The outdoor and early hours biting behavior of the An. gambiae complex could be a threat for success of current indoor based interventions and hence, tools could be designed to reduce this threat.

scholarly journals New insights into malaria vector bionomics in Lao PDR: a nationwide entomology survey

2020 ◽  
Author(s):  
Sebastien Marcombe ◽  
Santi Maithaviphet ◽  
Julie Bobichon ◽  
Nothasin Phommavan ◽  
Simone Nambanya ◽  
...  
Keyword(s):  
Molecular Identification ◽  
Sibling Species ◽  
Rural Areas ◽  
Lao Pdr ◽  
Malaria Vectors ◽  
Human Landing Catch ◽  
Morphological Identification ◽  
Anopheles Mosquitoes ◽  
Malaria Burden ◽  
Human Landing

Abstract Background . In Laos, the malaria burden remains high despite a significant reduction of cases during the last decade. In the context of the disease elimination by 2030, a nationwide entomological survey was conducted to better understand the distribution, abundance and behavior of major malaria vectors ( Anopheles spp.) in the country. Methods . Mosquito collections were implemented in ten villages from ten provinces during the rainy and dry seasons of 2014 and 2015 by using human landing catch (HLC) and cow bait collection (CBC) methods. After morphological identification in the field, molecular identification of the sibling species of Anopheles mosquitoes from the Funestus, Leucosphyrus, and Maculatus groups were determined using PCR specific alleles. A screening of Plasmodium falciparum and P. vivax infections in the vectors was carried out by quantitative PCR assays. Results. A total of 14,146 adult mosquitoes representing 25 different Anopheles species were collected and morphologically identified. Molecular identification revealed the presence of 12 sibling species within the main primary vector groups including An. maculatus s.s., An. rampae , An. sawadwongporni , An. pseudowillmori , An. dravidicus , An. minimus s.s., An. aconitus , An. pampanai , An. harrisoni , An. dirus s.s., An. baimaii , An. nemophilous . Anopheles maculatus and An. minimus were predominant during both the dry and rainy seasons, but showed highly zoophilic preferences (Zoophilic index of 98% and 95%, respectively). Overall, 22% of the total malaria vectors were collected between 10:00 PM and 5:00 AM indoors when people are sleeping. Twenty-seven percent of primary and secondary vectors were collected outdoors before 10:00 PM or after 5:00 AM, times when people are usually awake and outdoors. Only two specimens were positive for P. falciparum , one An. aconitus from Phongsaly and one An. minimus from Vientiane Province Conclusions. The results indicate that people living in rural areas in Laos are constantly exposed to malaria vectors throughout the year and specifically outdoors. The use of LLINs/IRS remains important but innovative tools and new strategies are needed to address locally, the early and outdoor malaria transmission. Lack of expertise in general entomological methods may further exacerbate the situation.

scholarly journals New vectors in northern Sarawak, Malaysian Borneo, for the zoonotic malaria parasite, Plasmodium knowlesi

2020 ◽  
Author(s):  
Joshua Ang Xin De ◽  
Khamisah Abdul Kadir ◽  
Dayang Shuaisah Awang Mohamad ◽  
Asmad Matusop ◽  
Paul Cliff Simon Divis ◽  
...  
Keyword(s):  
Plasmodium Knowlesi ◽  
Phylogenetic Analyses ◽  
Plasmodium Species ◽  
Malaria Vectors ◽  
Anopheles Mosquitoes ◽  
Zoonotic Malaria ◽  
Parasite Plasmodium ◽  
Coi Sequences ◽  
Anopheles Barbirostris ◽  
Malaysian Borneo

Abstract Background: The vectors for Plasmodium knowlesi, a significant cause of human malaria in Southeast Asia, identified previously in nature all belong to the Anopheles Leucosphyrus Group. Only one study has been previously undertaken in Sarawak, Malaysian Borneo, to identify vectors of P. knowlesi , where Anopheles latens was incriminated as the vector in Kapit, central Sarawak. A study was therefore undertaken to identify malaria vectors in a different location in Sarawak. Methods: Mosquitoes found landing on humans and resting on leaves over a 5-day period at two sites in the Lawas District of northern Sarawak were collected and identified. DNA samples extracted from salivary glands of Anopheles mosquitoes were subjected to nested PCR malaria-detection assays. The small sub-unit ribosomal RNA (SSUrRNA) genes of Plasmodium , and the internal transcribed spacer 2 (ITSII) and mitochondrial cytochrome c oxidase subunit 1 (COI) sequences of the mosquitoes were derived from the Plasmodium -positive samples for phylogenetic analyses. Results: A total of 65 anophelines and 127 culicines were collected. By PCR, six An. balabacensis and five An. barbirostris Clade VI were found to have single P. knowlesi infecions while three other An. balabacensis had either single, double or triple infections with P. inui, P. fieldi, P. cynomolgi and P. knowlesi . Phylogenetic analyses of the Plasmodium SSUrRNA genes confirmed 3 An. barbirostris Clade VI and 3 An. balabacensis with single P. knowlesi infections, while 3 other An. balabacensis had two or more Plasmodium species of P. inui, P. knowlesi, P. cynomolgi and possibly novel species of Plasmodium . Phylogenies inferred from the ITSII and COI sequences of An. balabacensis and An. barbirostris Clade VI indicate that the former is genetically indistinguishable from An. balabacensis in Borneo while the latter is a novel sibling species belonging to the Anopheles Barbirostris Subgroup. Conclusions: New vectors for P. knowlesi in Sarawak were identified, including An. barbirostris Clade VI , which is a species that does not belong to the Anopheles Leucosphyrus Group.

scholarly journals Probe-based multiplex qPCR identifies bloodmeal hosts in Anopheles mosquitoes from Papua New Guinea

2019 ◽  
Author(s):  
John B Keven ◽  
Georgia Artzberger ◽  
Mary L. Gillies ◽  
Rex B. Mbewe ◽  
Edward D. Walker
Keyword(s):  
Quantitative Pcr ◽  
Nuclear Dna ◽  
Control Measures ◽  
Molecular Probe ◽  
Malaria Vectors ◽  
Anopheles Mosquitoes ◽  
Vertebrate Hosts ◽  
Host Blood ◽  
Blood Meals

Abstract Background: Determination of bloodmeal hosts in blood-fed female Anopheles mosquitoes is important for evaluating vectorial capacity of vector populations and assessing effectiveness of vector control measures. Sensitive molecular methods are needed to detect traces of host blood in mosquito samples, to differentiate hosts, and to detect mixed host blood meals. This paper describes a molecular probe-based quantitative PCR for identifying bloodmeal hosts in Anopheles malaria vectors from Papua New Guinea.Methods: TaqMan oligonucleotide probes targeting specific regions of mitochondrial or nuclear DNA of the three primary Anopheles bloodmeal hosts – humans, pigs and dogs – were incorporated into a multiplex, quantitative PCR which was optimized for sensitivity and specificity.Results: Amplification of serially diluted DNA showed that the quantitative PCR detected as low as 10-5 ng/μl of host DNA. Application to field-collected, blood-fed Anopheles showed that the quantitative PCR identified the vertebrate hosts for 335/375 (89%) of mosquitoes whereas only 104/188 (55%) of bloodmeal samples tested in a conventional PCR were identified. Of 188 blood-fed Anopheles that were analyzed in both PCR methods, 16 (8.5%) were identified as mixed bloodmeals by the quantitative PCR whereas only 3 (1.6%) were mixed bloodmeals by the conventional PCR.Conclusions: The multiplex quantitative PCR described here is sensitive at detecting low DNA concentration and mixed host DNA in samples and useful for bloodmeal analysis of field mosquitoes, in particular mixed-host bloodmeals.

scholarly journals Impact of sugarcane irrigation on malaria vector Anopheles mosquito fauna, abundance and seasonality in Arjo-Didessa, Ethiopia

2020 ◽  
Author(s):  
Assalif Demissew Shifera ◽  
Dawit Hawaria ◽  
Solomon Kibret ◽  
Abebe Animut ◽  
Arega Tsegaye ◽  
...  
Keyword(s):  
Species Composition ◽  
Malaria Vector ◽  
Mosquito Species ◽  
Malaria Vectors ◽  
Anopheline Mosquito ◽  
Chi Square ◽  
Anopheles Species ◽  
Mosquito Abundance ◽  
Anopheles Mosquitoes ◽  
The Impact

Abstract Background: Although irrigation activities are increasing in Ethiopia, limited studies evaluated their impact on malaria vector mosquito composition, abundance and seasonality. This study aimed at evaluating the impact of sugarcane irrigation on species composition, abundance and seasonality of malaria vectors. Methods : Adult Anopheles mosquitoes were collected using CDC light traps from three irrigated and three non-irrigated clusters in and around Arjo-Didessa sugarcane irrigation scheme in southwestern Ethiopia. Mosquito collections were conducted in four seasons: two wet and two dry, in 2018 and 2019. Mosquito species composition, abundance and seasonality were compared between irrigated and non-irrigated clusters. Anopheles mosquitoes were identified to species using morphological keys and An. gambiae s.l to sibling species using PCR. Chi-square was used to analyze the association between Anopheles species occurrence and environmental and seasonal parameters. Results: Overall, 2,108 female Anopheles mosquitoes comprising of six species were collected. Of these, 92.7% (n=1954) were from irrigated clusters and 7.3% (n=154) from the non-irrigated. An. gambiae s.l was the most abundant (67.3%) followed by An. coustani complex (25.3 %) and An. pharoensis (5.7%). PCR based identification revealed that 74.7% (n=168) of the An. gambiae s.l were An. arabiensis and 22.7% (n=51) An. amharicus . Density of An. gambiae s.l. (both indoor and outdoor) was higher in irrigated than non-irrigated clusters. The overall anopheline mosquito abundance during the wet seasons (87.2%; n=1837) was higher than the dry seasons (12.8%; n=271). Conclusion : The ongoing sugarcane irrigation activities in Arjo-Didessa created conditions suitable for increased malaria transmitting Anopheles species diversity and abundance. This in turn could drive malaria transmission in Arjo-Didessa and its environs in both dry and wet seasons. Thus, currently practiced malaria vector interventions need to be strengthened and consider larval source management to reduce vector abundance in the irrigated areas. Key Words: Malaria, Irrigation, Anopheles mosquitoes, vector density, An. amharicus , Ethiopia

Sign in / Sign up

Export Citation Format

Share Document