An integrin required for the encapsulation immune response in the tobacco hornworm, Manduca sexta L. (Lepidoptera: Sphingidae).
In a series of in vivo encapsulation assays in the tobacco hornworm, Manduca sexta, a collection of anti-hemocyte monoclonal antibodies (mAbs) was screened for their ability to inhibit cellular encapsulation. Two of the mAbs that inhibited this immune response and incidentally specifically bind plasmatocytes, MS13 and MS34, were used to isolate a ? 90 kDa protein. Several short peptide sequences contained within this protein were acquired via Edman degradation. Degenerate primers based on two of these peptide sequences and total RNA from M. sexta hemocytes were used to perform RT-PCR and 5´ and 3´ RACE. This resulted in a full-length cDNA sequence of 2426 bp. A 2301 bp open reading frame within this cDNA sequence codes for a protein of 767 residues. This protein, denominated [Beta]Ms1, exhibits significant sequence homology to the [Beta]-subunits of integrins, which are a family of transmembrane, heterodimeric glycoproteins that possess adhesive properties. Analysis of recombinant segments of [Beta]Ms1 showed that the protein produced from the PCR product is the antigen to MS13 and MS34 and that these mAbs bind to the region of the integrin that contains the extracellular binding site. Northern blot analysis of various M. sexta tissues together with immunofluorescence labeling with MS13 and MS34 shows that [Beta]Ms1 is solely expressed in plasmatocytes. The totality of these experiments demonstrates that integrins are essential for the cellular immune response of encapsulation.
School:Kansas State University
School Location:USA - Kansas
Source Type:Master's Thesis
Keywords:encapsulation integrin manduca sexta insect cellular immunity hemocyte cell adhesion biology 0379 entomology 0353 chemistry biochemistry 0487
Date of Publication:01/01/2007