Bio:
I joined the Dimopoulos group as a postdoctoral fellow in 2008 directly after receiving my Ph.D. from Colorado State University. My research interests involve microbiological and molecular aspects of the interactions between mosquitoes and vector-borne pathogens including arthropod-borne viruses and Plasmodium parasites. More specifically, I am interested in studying how vectored pathogens are able to infect the mosquito and what mechanisms are used by the mosquito and its natural microflora to interfere with transmission of the pathogens.

Current research:

Bacteria-mediated modulation of Plasmodium transmission in Anopheles

Our lab and others have shown that the native bacteria within the mosquito midgut can modulate infection and eventual transmission of vector-borne pathogens (Dong et al, 2009; Xi et al, 2008; Meister et al 2009). Using bacteria that were isolated from wild mosquito populations collected in Macha, Zambia (Figure 1), my main project has begun to investigate how the natural mosquito microbiota modulates Plasmodium parasite development and infection of the Anopheles vector.


Figure 1. The Malaria Institute at Macha, Zambia research facility and collection of wild mosquitoes by human-landing catch.

Similar to previous studies (Pumpuni et al, 1993; 1996; Gonzalez-Ceron et al, 2003), we have observed that only Gram-negative bacteria are able to inhibit mosquito-stage development of Plasmodium.  We have identified one bacterium that strongly interferes with early mosquito-stage development of the parasite.  Interestingly, the bacteria appear to mediate this process without a significant contribution by the mosquito immune system. 


Figure 2. P. falciparum parasites develop normally in vitro (left panel), but addition of bacteria (right panel) inhibits development. 1000x total mag.

In fact, in vitro development of the rodent malaria parasite P. berghei is also inhibited by the bacterium (Fig 2), suggesting that the mosquito does not significantly contribute to our observed phenotype.  Currently, we are investigating the mechanism of inhibition exhibited by this particular bacterium. We hypothesize that a diffusible bacterial product may mediate the parasites and are pursuing this and other avenues of research to elucidate the mechanism of action exhibited by the bacteria. This work could lead to the discovery of novel malaria control strategies using these bacteria

O’nyong-nyong virus-derived transducing systems for malaria control
Although little research has focused on O’nyong-nyong virus (Family Togaviridae: genus Alphavirus), it remains an important mosquito-transmitted virus that causes outbreaks of human disease. ONNV is the only virus known to be transmitted by Anopheles mosquitoes, making it a unique model system for investigation. Taking advantage of a virus transducing system that can produce non-viral transcripts from an engineered promoter (ex. Fig 3), we will determine whether ONNV can be manipulated as a suitable strategy to investigate Plasmodium infection of the mosquito. Using RNA interference-based strategies, we will produce viruses that are able to decrease specific mosquito transcripts, including anti-Plasmodium effector molecules and negative regulators of the mosquito innate immune system, in infected cells. This work has only recently begun, but could lead to novel viral paratransgenic strategies of malaria control.


Figure 3. Anopheles gambiae midgut infected with ONNV expressing green fluorescent protein. Black and white image- 200x total mag.