Research Description

Overview

At the broadest level, research conducted by my group is directed towards understanding how parasites survive within their hosts. Our long-term goals are focused on finding new ways to interrupt transmission of parasites to and from insect vectors. We are particularly interested in the interactions between the mosquito immune system and malaria parasites.

We also carry out research on problems of special importance to Wisconsin. That research has focused on examination of alternative ways to repel mosquitoes, the use of vitamin B as a systemic repellent, and the ecology and biology of Lyme Disease and anaplasmosis in Wisconsin. Currently, this part of the research program is directed towards investigating West Nile virus.

Our research has been funded by multiple sources, principally NIH, WHO, and the University of Wisconsin (USDA-Hatch).

Current focal areas include:

1) Proteomic studies to identify hemolymph and midgut proteins altered during parasite infections .

This research is designed to identify proteins that play a role in mediating parasite infections. Some of these proteins may not be identifiable through microarray or other transcript-based technology. We combine 2D gel separation with tandem mass spectrophotometry to find and id proteins using the Anopheles dirus/P. falciparum and A. gambiae/P. berghei systems. We have also examined proteins that are altered during responses to bacteria and Sephadex bead injection, two alternative immune challenges that can elicit some of the same responses as parasites. Identified proteins are then characterized at the level of the gene and gene silencing is used to further examine function. Sample publications include:

Shi L. and Paskewitz S.M. Proteomics and Insect Immunity. Invertebrate Survival Journal 3:4-17. 2006.

Paskewitz S.M. and Shi L. The hemolymph proteome of Anopheles gambiae. Insect Biochemistry and Molecular Biology. 35:815-824. 2005 .

Shi, L. and Paskewitz S.M. Identification and molecular characterization of two immune-responsive chitinase-like proteins from Anopheles gambiae. Insect Molecular Biology. 13:387-398. 2004.

Chun J., McMaster, J., Han Y.S., Schwartz A. and Paskewitz S.M. Two-dimensional gel analysis of hemolymph proteins from Plasmodium-melanizing and nonmelanizing strains of Anopheles gambiae. Insect Molecular Biology 9:39-45. 2000.

2) The role of antimicrobial peptides/proteins in mosquito immunity and Plasmodium development.

This new area of research is directed toward investigation of the role of lysozyme in mosquito biology. There are 8 lysozyme genes in Anopheles gambiae, all of which are expressed at various stages and tissues. Several demonstrate structural features that suggest they have novel functions.

We are examining the role of these proteins in relation to bacterial proliferation in the midgut after blood-feeding, larval feeding biology, and parasite/bacterial infections.

Sample publications include:

Li Bin, Calvo E., Marinotti O., James A.A. and Paskewitz S.M. Characterization of the c-type lysozyme gene family in Anopheles gambiae. Gene 360:131-139. 2005.

Lowenberger C.A. , Kamal S., Chiles J., Paskewitz S., Bulet P., Hoffmann J.A., and Christensen B.M. Mosquito-Plasmodium interactions in response to immune activation of the vector. Experimental Parasitology 91:59-69. 1999.

3) Factors controlling melanotic encapsulation of parasites.

Melanotic encapsulation is a process where the pigment melanin is deposited around malaria parasites, filarial parasites, bacteria or Sephadex beads. Melanin formation is also important in egg development and cuticle formation. We are investigating the proteins that are involved in production of this compound. In particular, we focus on a group of enzymes called serine proteases. We have identified a number of serine proteases in Anopheles gambiae and are currently characterizing their activity in relation to melanization. Inhibitors of phenoloxidase are also under investigation. Sample publications include:

BIN LI and SUSAN PASKEWITZ. A role for lysozyme in melanization of Sephadex beads in Anopheles gambiae. Journal of Insect Physiology. In press.

SUSAN PASKEWITZ, OLGA ANDREEV and LEI SHI. Gene silencing of serine proteases affects melanization of Sephadex beads in Anopheles gambiae. Insect Biochemistry and Molecular Biology. 36: 701-711. 2006.

SHI, L., LI B., and PASKEWIZ S.M. Cloning and characterization of a putative phenoloxidase inhibitor (POI) from Anopheles gambiae. Insect Molecular Biology. 15:313-320. 2006.

LI B., HUANG Y., and PASKEWITZ S.M. Hen egg white lysozyme as an inhibitor of mushroom tyrosinase. FEBS Letters 250:1877-1882. 2006.

Christophides, G.K., Zdobnov E., Barillas C., Blandin S., Blass C., Brey P.T., Collins F.H., Danielli A., Dimopoulos G., Hetru C., Hoa N.T., Hoffmann J.A., Kanzok S.M., Letunic I., Levashina E., Loukeris T.G., Luna C., Lycett G., Meister S., Michel K., Moita L.F., Mueller H., Osta M., Paskewitz S.M., Reichhart J., Rzhetsky A., Troxler L., Vernick K.D., Vlachou D., Volz J., Mering C., Xu J., Zheng L., Bork P., Kafatos F.C. Immunity related genes and gene families in Anopheles gambiae: A comparative genomic analysis. Science. 298: 159-165. 2002.

GORMAN M.J. and PASKEWITZ S.M. Serine proteases as mediators of mosquito immune responses. Insect Biochemistry and Molecular Biology. 31:257-262. 2001.

GORMAN M.J., ANDREEVA O.V. and PASKEWITZ S.M. Sp22D: a multidomain serine protease with a putative role in insect immunity. Gene 251:9-17. 2000.

GORMAN M.J., ANDREEVA O. and PASKEWITZ S.M. Molecular characterization of five serine protease genes cloned from Anopheles gambiae hemolymph. Insect Biochemistry and Molecular Biology. 30:35-46. 2000.

PASKEWITZ S.M., REESE-STARDY S., AND GORMAN M.J. An easter-like serine protease from Anopheles gambiae exhibits changes in transcript levels following immune challenge. Insect Molecular Biology. 8:329-338. 1999.

4) West Nile virus in mosquitoes in southern Wisconsin

 
Adams rain garden

 
Uranotaenia

Gravid trap Patrick

 

1. Compare human landing, CO2-baited light trap, and gravid trap collections of mosquitoes at six sites to determine validity of traps in quantifying relative abundance of human-feeding mosquitoes and to produce temporal profiles of mosquito species composition. Assess these mosquito samples for the presence of WNV.
2. Collect fed mosquitoes and determine the blood meal source by serological and polymerase chain reaction-based methods.
3. Compare circadian feeding rhythms for suspected bridge vectors by collecting humanlanding mosquitoes at different periods of the day.