Complete Sporogony of Plasmodium Relictum (Lineage Pgrw4) in Mosquitoes Culex Pipiens Pipiens, with Implications on Avian Malaria Epidemiology
Total Page：16
File Type：pdf, Size：1020Kb
Complete sporogony of Plasmodium relictum (lineage pGRW4) in mosquitoes Culex pipiens pipiens, with implications on avian malaria epidemiology Gediminas Valkiūnas, Rita Žiegytė, Vaidas Palinauskas, Rasa Bernotienė, Dovilė Bukauskaitė, Mikas Ilgūnas, Dimitar Dimitrov, et al. Parasitology Research Founded as Zeitschrift für Parasitenkunde ISSN 0932-0113 Volume 114 Number 8 Parasitol Res (2015) 114:3075-3085 DOI 10.1007/s00436-015-4510-3 1 23 Your article is protected by copyright and all rights are held exclusively by Springer- Verlag Berlin Heidelberg. This e-offprint is for personal use only and shall not be self- archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”. 1 23 Author's personal copy Parasitol Res (2015) 114:3075–3085 DOI 10.1007/s00436-015-4510-3 ORIGINAL PAPER Complete sporogony of Plasmodium relictum (lineage pGRW4) in mosquitoes Culex pipiens pipiens,withimplicationsonavian malaria epidemiology Gediminas Valkiūnas1 & Rita Žiegytė1 & Vaidas Palinauskas1 & Rasa Bernotienė1 & Dovilė Bukauskaitė1 & Mikas Ilgūnas1 & Dimitar Dimitrov1,2 & Tatjana A. Iezhova 1 Received: 22 April 2015 /Accepted: 29 April 2015 /Published online: 10 May 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract Plasmodium relictum (lineage pGRW4) causes ma- pGRW4 in mosquitoes was confirmed by PCR-based testing laria in birds and is actively transmitted in countries with warm of (1) the sporozoites present in salivary glands and (2) the single climates and also temperate regions of the New World. In Eu- oocysts, which were obtained by laser microdissection from rope, the lineage pGRW4 has been frequently reported in many infected mosquito midguts. This study shows that P. relictum species of Afrotropical migrants after their arrival from winter- (pGRW4) completes sporogony in C. p. pipiens at relatively low ing grounds, but is rare in European resident birds. Obstacles for temperatures. We conclude that there are no restrictions for transmission of this parasite in Europe have not been identified. spreadingthisbirdinfectioninEuropefromthepointofview Culex quinquefasciatus is an effective vector of pGRW4 malar- of vector availability and temperature necessary for sporogony. ia, but this mosquito is absent from temperate regions of Eurasia. Other factors should be considered and were discussed for the It remains unclear if the lineage pGRW4 completes sporogony explanation of rare reports of this malaria parasite in Europe. in European species of mosquitoes. Here we compare the spo- rogonic development of P. relictum (pGRW4) in experimentally Keywords Avian malaria . Plasmodium relictum . pGRW4 . infected mosquitoes Culex pipiens pipiens form molestus, Sporogony . Culex mosquitoes . Ochlerotatus cantans C. quinquefasciatus,andOchlerotatus cantans. The pGRW4 parasite was isolated from a garden warbler Sylvia borin, multi- plied, and used to infect laboratory-reared Culex spp. and wild- Introduction caught Ochlerotatus mosquitoes by allowing them to take blood meals on infected birds. The exposed females were maintained Plasmodium relictum (Haemosporida, Plasmodiidae) causes at a mean laboratory temperature of 19 °C, which ranged be- malaria in birds and is the first in frequency of the occurrence tween14°Catnightand24°Cduringdaytime.Theywere of avian malaria parasite reported from over 300 species of birds dissected on intervals to study the development of sporogonic at all continents, except the Antarctic (Garnham 1966;Valkiūnas stages. Only ookinetes developed in O. cantans; sporogonic 2005; Atkinson et al. 2008). Recent polymerase chain reaction development was abortive. The parasite completed sporogony (PCR)-based studies identified two P. relictum lineages, which in both Culex species, with similar patterns of development, and are particularly and widely distributed both by hosts and geo- sporozoites were reported in the salivary glands 16 days after graphically; these are pSGS1 and pGRW4 (Beadell et al. 2006; infection. The presence of sporogonic stages of the lineage Ejiri et al. 2009;Clarketal.2014; Perkins 2014). Both parasite lineages have been reported in birds all over the world, but areas of their transmission are different (Marzal et al. 2011). * Gediminas Valkiūnas The lineage pSGS1 of P. relictum is cosmopolitan in trans- [email protected] mission (Bensch et al. 2009; Marzal et al. 2015) probably be- cause numerous bird and mosquito species are susceptible to this 1 Nature Research Centre, Akademijos 2, LT-08412 Vilnius infection (Valkiūnas 2005;Atkinsonetal.2008). Culex pipiens 2100, Lithuania mosquitoes, which are distributed worldwide, are effective vec- 2 Institute of Biodiversity and Ecosystem Research, Bulgarian tors of this parasite (Vézilier et al. 2010; Kazlauskienė et al. Academy of Sciences, 2 Gagarin Street, 1113 Sofia, Bulgaria 2013), and the sporogony completes at a temperature of 12– Author's personal copy 3076 Parasitol Res (2015) 114:3075–3085 30 °C (Garnham 1966;Valkiūnas 2005; Žiegytė et al. 2014). Sciences on the Curonian Spit in the Baltic Sea (55° 09′ N, 20° That enables transmission of the pSGS1 parasite in countries 52′ E) in May–July, 2013 and 2014. Experimental procedures both with warm and cold climates, for example in northern Nor- of this study were approved by the International Research Co- way (Marzal et al. 2011). operation Agreement between the Biological Station Rybachy Opposite to the pSGS1 parasite, the lineage pGRW4 of of the Zoological Institute of the Russian Academy of Sci- P. relictum has been reported to be actively transmitted mainly ences and Institute of Ecology of Nature Research Centre in countries with warm climates (Ricklefs et al. 2004; Beadell (25-05-2010). All efforts were made to minimize handling et al. 2006;Benschetal.2009; Marzal et al. 2011; Loiseau et al. time and potential suffering of birds. None of the experimental 2012). Interestingly, there are numerous reports of the pGRW4 birds suffered apparent injury during the experiments. parasite in European migrants after their arrival from African Nine juvenile siskins Carduelis spinus were caught and used wintering grounds, where the birds gain malaria (Bensch et al. for experimental infection (three birds) and control (six birds). 2007;Hellgrenetal.2007; Beadell et al. 2009), but a few The controls were used to monitor the absence of natural trans- studies detected this infection in resident European birds (Ferrer mission in the laboratory. All birds were kept at quarantine in a et al. 2012; Ferraguti et al. 2013; Drovetski et al. 2014), sug- mosquito-free room approximately for a week (adaptation pe- gesting a lack of active transmission in Europe. Factors preclud- riod) before the experiments. Blood was taken from the birds ing transmission of the pGRW4 parasite in Europe remain un- by puncturing the brachial vein. About 30 μl of whole blood clear. Culex quinquefasciatus is an effective vector of this par- was taken in heparinized microcapillaries and stored in SET asite (Atkinson et al. 2008;LaPointeetal.2010; Freed and buffer (Hellgren et al. 2004)formolecularanalysis.Twoblood Cann 2013), but this insect is absent from temperate regions films were prepared from each bird immediately after with- of Europe where C. pipiens mosquitoes act as active vectors of drawal of the blood. They were air dried, fixed in absolute avian malaria (Vézilier et al. 2010;Kazlauskienė et al. 2013; methanol, and stained with Giemsa, as described by Valkiūnas Cornet et al. 2013). It remains unclear if the lineage pGRW4 et al. (2008). Bird blood was tested for parasites on days 2 and 7 can complete sporogony in C. pipiens and other widespread after their arrival at the laboratory. All birds were uninfected European mosquitoes and if that happens at relatively low tem- with blood parasites, as revealed by microscopic examination peratures. The Hawaiian strain of pGRW4 parasite completed of blood films and PCR-based detection methods (see below). sporogonic development in C. quinquefasciatus at constant lab- We used one P. relictum (pGRW4) strain, which was isolat- oratory and mean field temperatures between 17 and 30 °C, but ed from a naturally infected garden warbler Sylvia borin in development decreased significantly below 21 °C, with a min- May 2013. Parasitemia was light (<0.001 %) in this bird. To imum threshold temperature of 13 °C (LaPointe et al. 2010). multiply the strain, two juvenile siskins were exposed by intra- The main aim of this study was to compare sporogonic de- muscular inoculation of approximately 50 μl of blood from the velopment of P. re li ct um (pGRW4) in mosquitoes Culex pipiens donor bird, as described by Palinauskas et al. (2008). pipiens form molestus and C. quinquefasciatus at a temperature, Parasitemia developed in all infected siskins. These birds were which is close to the long-term mean air degrees reported in maintained in a mosquito-free aviary and were used as donors European temperate regions during the warmest months of the of gametocytes to infect mosquitoes in 2014, i.e., a year after