Salivary AsHPX12 influences pre-blood meal associated behavioral properties in Anopheles stephensi

Background & objectives: A successful blood meal acquisition process by an adult female mosquito is accomplished through salivary glands, which releases a cocktail of proteins to counteract the vertebrate host’s immune homeostasis. Here, we characterize a salivary-specific Heme peroxidase family member HPX12, originally identified from Plasmodium vivax infected salivary RNAseq data of the mosquito Anopheles stephensi. Methods: To demonstrate we utilized a comprehensive in silico and functional genomics approach. Results: Our dsRNA-mediated silencing experiments demonstrate that salivary AsHPX12 may regulate pre-blood meal-associated behavioral properties such as probing time, probing propensity, and host attraction. Altered expression of the salivary secretory and antennal proteins expression may have accounted for salivary homeostasis disruption resulting in the unusual fast release of salivary cocktail proteins and delayed acquisition of blood meal in the AsHPX12 knockdown mosquitoes. We also observed a significant parallel transcriptional modulation in response to blood feeding and P. vivax infection. Interpretation & conclusion: With this work, we establish a possible functional correlation of AsHPX12 role in the maintenance of salivary physiological-homeostasis, and Plasmodium sporozoites survival/ transmission, though the mechanism is yet to unravel.

Molecular Identification of Haemadipsa rjukjuana (Hirudiniformes: Haemadipsidae) in Gageo Island, Korea

There are 60 species of blood-feeding land leeches, 50 species belonging to the family Haemadipsidae and 10 species belonging to the family Xerobdellidae. Despite recent papers on the land leeches, their taxonomic identification is not fully understood, especially at a species level. In Korea, there have been no historical records of the terrestrial leeches, but recently an unrecorded blood-feeding land leech was discovered at Gageo-do (Island), Korea. Molecular analysis was used to identify the species of 29 leeches collected from Mt. Dock-Sil in Gageo-do. Conventional PCR was conducted using nuclear 18S rRNA and mitochondrial cytochrome c oxidase subunit 1 (CO1) genetic marker. The 18S rRNA sequences revealed that the leeches share 99.9% identity with Haemadipsa rjukjuana (inhabiting Taiwan), and the CO1 sequences revealed that the leeches are very close to H. rjukjuana (inhabiting Taiwan). The CO1 sequences were separated into 2 categories, 1 with 94.6% and the other with 94.3% similarity to the H. rjukjuana L00115A (inhabiting Taiwan). This new finding of the land leech is the first record in Korea. In addition, the north range of the distribution of the blood-feeding leech (Hirudiniformes: Haemadipisidae) should be reconsidered including Korea.

Blood feeding patterns of Nyssomyia intermedia and Nyssomyia neivai (Diptera, Psychodidae) in a cutaneous leishmaniasis endemic area of the Ribeira Valley, State of São Paulo, Brazil

Introduction The aim of this study was to identify the blood feeding sources of Nyssomyia intermedia (Ny. intermedia) and Nyssomyia neivai (Ny. neivai), which are Leishmania vectors and the predominant sandfly species in the Ribeira Valley, State of São Paulo, Brazil, an endemic area for cutaneous leishmaniasis. Methods Specimens were captured monthly between February 2001 and December 2003 on a smallholding and a small farm situated in the Serra district in the Iporanga municipality. The blood meals of 988 engorged females were tested using the avidin-biotin immunoenzymatic enzyme-linked immunosorbent assay (ELISA). Seven blood meal sources were investigated: human, dog, chicken, bovine, pig, horse and rat. Results The results showed that among the females that fed on one or more blood sources, the respective percentages for Ny. intermedia and Ny. neivai, respectively, were as follows: human (23% and 36.8%), pig (47.4% and 26.4%), chicken (25.7% and 36.8%) and dog (3.9% and 0%), and the differences in the blood sources between the two species were statistically significant (p = 0.043). Conclusions Both species had predominant reactivity for one or two blood sources, and few showed reactivity indicating three or four sources. Many different combinations were observed among the females that showed reactivity for more than one source, which indicated their opportunistic habits and eclecticism regarding anthropic environmental conditions. .

Circadian clock of Aedes aegypti: effects of blood-feeding, insemination and RNA interference

Mosquitoes are the culprits of some of the most important vector borne diseases. A species’ potential as a vector is directly dependent on their pattern of behaviour, which is known to change according to the female’s physiological status such as whether the female is virgin/mated and unfed/blood-fed. However, the molecular mechanism triggered by and/or responsible for such modulations in behaviour is poorly understood. Clock genes are known to be responsible for the control of circadian behaviour in several species. Here we investigate the impact mating and blood-feeding have upon the expression of these genes in the mosquito Aedes aegypti . We show that blood intake, but not insemination, is responsible for the down-regulation of clock genes. Using RNA interference, we observe a slight reduction in the evening activity peak in the fourth day after dstim injection. These data suggest that, as in Drosophila , clock gene expression, circadian behaviour and environmental light regimens are interconnected in Ae. aegypti .

A transient increase in total head phosphotyrosine levels is observed upon the emergence of Aedes aegypti from the pupal stage

Phosphorylation and dephosphorylation of protein tyrosine residues constitutes a major biochemical regulatory mechanism for the cell. We report a transient increase in the total tyrosine phosphorylation of the Aedes aegypti head during the first days after emergence from the pupal stage. This correlates with an initial reduction in total head protein tyrosine phosphatase (PTP) activity. Similarly, phosphotyrosine (pTyr)-containing bands are seen in extracts prepared from both male and female heads and are spread among a variety of structures including the antennae, proboscis and the maxillary palps combined with the proboscis. Also, mosquitoes treated with sodium orthovanadate, a classical PTP inhibitor, show reduced blood-feeding activity and higher head tyrosine phosphorylation levels. These results suggest that pTyr-mediated signalling pathways may play a role in the initial days following the emergence of the adult mosquito from the pupal stage.

Laboratory and semi-field evaluation of long-lasting insecticidal nets against leishmaniasis vector, Phlebotomus (Phlebotomus) duboscqi in Kenya.

Background & objectives: Phlebotomine sandflies are vectors of leishmaniases and other diseases. Long-lasting insecticidal nets (LLINs) as possible tools for control have not been widely tested against them. The objective of this study was to determine the efficacy of Olyset® Net and PermaNet® LLINs alongside a local brand, K-O Tab® treated net (Supanet) against Phlebotomus duboscqi female sandflies. Methods: Four replicates of unwashed and 20x washed Olyset Nets and PermaNets, K-O Tabtreated and untreated Supanet and ‘no net’ treatments were evaluated against sandflies within the laboratory by tunnel tests and in semi-field conditions in the greenhouse model for their efficacy. Results: All bednets allowed entry of P. duboscqi sandflies and subsequent blood-feeding. Olyset net’s blood feeding inhibition was significantly higher than that of Supanet in the laboratory but not in semi-field condition. Of the LLINs, only Olyset net had sandflies that could not feed significantly more than those of Supanet. Additionally, no significant efficacy difference was observed between LLINs washed 20x and unwashed ones. The only significant difference noted in number of sandflies that were found dead or paralyzed within bednets in the semi-field condition was between Olyset and K-O Tab treated Supanet. In the laboratory, unwashed Olyset had a significantly higher number of sandflies killed than all other bednet treatments. Conclusion: Olyset net use in areas where sandflies are nuisance biters and/or disease vectors could be more beneficial in preventing sandfly bites than other tested bednets. It is recommended that mesh sizes of LLINs should be smaller for control of sandflies than those used for control of mosquitoes.

Preferência alimentar sanguínea de Lutzomyia whitmani (Diptera, Psychodidae) em área de transmissão de leishmaniose cutânea americana, no Estado do Maranhão, Brasil / Blood feeding preference of Lutzomyia whitmani (Diptera, Psychodidae) in a transmission area for American cutaneous leishmaniasis in the State of Maranhão, Brazil

O objetivo deste estudo foi determinar as fontes de alimento sanguíneo de fêmeas de Lutzomyia whitmani, espécie de flebotomíneo incriminada no Maranhão como principal vetor da leishmaniose cutânea americana. Para isso, 70 fêmeas desta espécie coletadas no município de Axixá, área com um dos maiores números de casos de leishmaniose cutânea americana em humanos no Maranhão, foram analisadas utilizando a técnica da precipitina. Dos indivíduos analisados, 90 por cento apresentaram reação a algum tipo de antissoro e dentre estes, 73 por cento apresentaram reações do tipo simples com predominância para sangue de galinha (22,2 por cento), roedor (14,3) e humano (12,7 por cento). Nas reações duplas predominaram as combinações galinha/humano (6,3 por cento), galinha/gambá (4,8 por cento), boi/humano e gambá/humano (3,2 por cento). Assim, concluímos que seres humanos, animais domésticos e sinantrópicos constituem fonte alimentar sanguínea para Lutzomyia whitmani podendo desempenhar um papel importante no ciclo de transmissão da leishmaniose cutânea americana explicando os casos da doença em Axixá.

The aim of this study was to determine the sources of blood meals for females of Lutzomyia whitmani, a phlebotomine species incriminated as the main vector for American cutaneous leishmaniasis in Maranhão. For this, 70 Lutzomyia whitmani females were collected in the municipality of Axixá, an area with one of the greatest numbers of cases of American cutaneous leishmaniasis in humans in Maranhão. They were analyzed using the precipitin technique. Ninety percent of the specimens showed a reaction to some type of antiserum positive immune reaction, among which 73 percent presented single reactions, with predominance for chicken blood (22 percent), rodent blood (14.3 percent) and human blood (12.7 percent). Among the double reactions, the predominant combinations were chicken/human (6.3 percent), chicken/opossum (4.8 percent), ox/human (3.2 percent) and opossum/human (3.2 percent). Thus, we conclude that humans and domestic and synanthropic animals are blood meal sources for Lutzomyia whitmani and may play an important role in the transmission cycle for American cutaneous leishmaniasis, thus explaining the cases of this disease in Axixá.

Free meals on long-distance cruisers: the vampire fish rides giant catfishes in the Amazon

The trichomycterid catfishes known as candirus are renowned for their blood feeding, but information on their habits under natural conditions is very fragmentary and generally restricted to hosts or habitats. We recorded an undescribed species of the vandelliine genus Paracanthopoma riding the giant jau catfish, Zungaro zungaro (Pimelodidae), in the upper Amazon. The candirus were found on the host's caudal and pectoral fins, as well as the base of the dorsal fin, with their snouts buried up to the eyes in the tough skin of the catfish host. All of them had small amounts of partly digested blood in the distal part of the gut. Along the host's dorsal fin base we found a few additional tiny holes, most of them healed. We suggest that Paracanthopoma feeds on the gill chamber of its hosts, and that the individuals we found were taking a ride partly buried into the host's skin. Our assumption seems supported by the widespread behaviour of vandelliine candirus taking blood from the gill region of their hosts, and by a report of Paracanthopoma parva found on the gills of another species of giant catfish, Brachyplatystoma vaillanti. Additionally, the Paracanthopoma sp. individuals we examined were not gorged with blood as usual for several vandelliines. Species within the genus Paracanthopoma have the longest and most robust snout, and the longest and strongest dentary teeth among blood-feeding candirus, which fit their drilling needs. Taking a ride on a giant host would be advantageous for Paracanthopoma candirus for several reasons: 1) dispersal; 2) no need to search for hosts to feed; and 3) protection from predators. The alternative explanation that Paracanthopoma takes blood from the tiny holes it drills in the skin seems unlikely, due to the recent finding that species of the genus Vandellia are unable to take blood from their hosts actively and cut open a major branchial artery to gorge themselves with blood due to the host's arterial...

Os bagres tricomicterídeos conhecidos como candirus são famosos por se alimentarem de sangue, mas as informações sobre seus hábitos, em condições naturais, são fragmentárias e restritas aos seus hospedeiros ou ambientes. Registramos uma espécie não descrita de candiru do gênero Paracanthopoma (Vandelliinae) sobre um jaú, Zungaro zungaro (Pimelodidae), no alto Rio Amazonas. Os candirus estavam sobre as nadadeiras caudal e peitoral e junto à base da dorsal, com seus focinhos enterrados até a altura dos olhos, no tegumento espesso do bagre hospedeiro. Os candirus continham pequenas quantidades de sangue parcialmente digerido na porção distal de seus tubos digestórios. Havia diversos orifícios rasos próximos à base da nadadeira dorsal do hospedeiro, a maioria cicatrizada. Sugerimos que Paracanthopoma se alimente na câmara branquial dos seus hospedeiros e que os candirus estejam viajando parcialmente enterrados na pele do jaú. Nossa suposição está apoiada no hábito de tomar sangue na região branquial dos hospedeiros, predominante entre os Vandelliinae, bem como por um registro de Paracanthopoma parva sobre as brânquias de uma outra espécie de grande bagre (Brachyplatystoma vaillanti). Além disso, os indivíduos de Paracanthopoma sp. não estavam empanturrados com sangue, como é usual para Vandelliinae. As espécies de Paracanthopoma têm o focinho mais longo e robusto entre os candirus hematófagos, além de dentes mandibulares longos e muito fortes, características adequadas ao hábito de perfurar a pele do hospedeiro. Viajar no corpo do hospedeiro seria vantajoso por diversos motivos: 1) dispersão; 2) não haver necessidade de procurar hospedeiros para se alimentar; 3) proteção contra predadores. A explicação alternativa, de que Paracanthopoma toma sangue nos pequenos furos que escava, não parece plausível, devido à recente descoberta de que espécies de Vandellia são incapazes de tomar sangue ativamente, pois fazem uma incisão numa das artérias...

Growth difference of Plasmodium vivax in Anopheles sinensis and An.anthropophagus during the periods of clinic attack and diapause of vivax malaria patients / 中国血吸虫病防治杂志

Objective To compare the growth of Plasmodium vivax in Anopheles sinensis(An.s) and Anopheles anthropophagus(An.a) during the periods of malaria clinic attack and diapause. Methods The blood samples of patients during the clinic attack and diapause of vivax malaria patients in the vivax epidemic area in China were collected, feeding the mosquitoes of An.s and An.a by using the artificial membrane feeding system in vivo in the lab, and the mosquitoes were dissected during the day 7-9th and 14th after the infection and the oocysts and sporozoites in the stomach and gland of the mosquitoes were counted, respectively. Results The oocyst positive rate in An.s fed by Plasmodium vivax during the fever stage was lower than that in non-fever stage, the sporozoite positive rate in An.a fed by Plasmodium vivax during the fever stage was lower than that in non-fever stage. The positive mosquito rate with oocyst and sporozoite infected by Plasmodium vivax in the fever stage to An.s and An.a were lower than those in non-fever stage. The infective sporozoite intensity of An.s fed by Plasmodium vivax in the fever stage was lower than that in non-fever stage, but the reverse result was found to An.a. Conclusion There is a significant difference between the periods of malaria clinic attack and diapause of the oocyst and sporozoite infection to An.s and An.a.

Susceptibility of Anopheles anthropophagus from different areas of China to Plasmodium vivax / 中国血吸虫病防治杂志

Objective To compare the susceptibility of Anopheles anthropophagus from Jiangsu, Guangdong and Liaoning provinces in China to Plasmodium vivax.Methods The blood samples of patients with P. vivax in endemic areas of China were collected to feed the mosquitoes of An. anthropophagus from different areas by using the artificial in vitro membrane feeding system in the lab, and then the mosquitoes were dissected during the 7-9th day and on the 14th day after the feeding and the oocysts and sporozoites in the stomach and salivy gland of mosquitoes were counted. Results The mosquitoes from Jiangsu, Guangdong and Liaoning were simultaneously fed with the blood of 35 cases of P. vivax. The oocyst positive rates of An. anthropophagus from Jiangsu, Guangdong and Liaoning during the 7-9th day after the feeding were 68.57%, 60.00% and 68.57%, as well as the sporozoite positive rates of them on the 14th day after the feeding were 22.86%, 14.29% and 22.86%, respectively. On the 7th day after the feeding, 228, 235, 228 mosquitoes of An. anthropophagus from Jiangsu, Guangdong and Liaoning were dissected, and the positive mosquito rates with oocyst infection were 28.07%, 25.11% and 26.75%, respectively. On the 14th day after the feeding, 150, 142, 135 mosquitoes of An. anthropophagus from the three areas were dissected, the positive rates with sporozoite infection were 10.67%, 8.45% and 11.85%, respectively. The num-bers of mosquitoes dissected with infective grade("+","++","+++","++++") of sporozoites of An. anthropophagus from Jiangsu, Guangdong and Liaoning were 4, 3, 2, 7; 2, 2, 3, 7 and 1, 6, 3, 8, respectively. Conclusions An. anthropophagus from Jiangsu, Guangdong and Liaoning is susceptible to the parasites of Plasmodium vivax and there is no significant difference among the susceptibilities of An. anthropophagus from the three areas to Plasmodium vivax.