Transformation of gypsy moth (Lymantria dispar) cell lines by infection with Glyptapanteles indiensis polydnavirus.

Glyptapanteles indiensis, a species of braconid parasitic wasp, infects its host Lymantria dispar (gypsy moth) with a polydnavirus (GiPDV) to suppress the host immune system during parasitization. Here it is shown that GiPDV can infect L. dispar cell lines and that a portion of the GiPDV genome is stably maintained in infected cells. Results of Southern hybridization analyses suggested that this portion of the GiPDV genome is integrated into the L. dispar cellular genome. This is the first report of an insect viral DNA molecule that can apparently integrate into lepidopteran insect cells.

Bacteriophage HK97 structure: wholesale covalent cross-linking between the major head shell subunits.

We describe initial genetic and structural characterizations of HK97, a temperate bacteriophage of Escherichia coli. We isolated 28 amber mutants, characterized them with respect to what phage-related structures they make, and mapped many of them to restriction fragments of genomic DNA. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of HK97 virions revealed nine different protein species plus a substantial amount of material that failed to enter the gel, apparently because it is too large. Five proteins are tail components and are assigned functions as tail fiber subunit, tail length template, and major shaft subunit (two and possibly three species). The four remaining proteins and the material that did not enter the gel are head components. One of these proteins is assigned as the portal subunit, and the remaining three head proteins in the gel and the material that did not enter the gel are components of the head shell. All of the head shell protein species have apparent molecular masses well in excess of 100 kDa; they share amino acid sequence with each other and also with a 42-kDa protein that is found in infected lysates and as the major component of prohead structures that accumulate in infections by one of the amber mutants. We propose that all of the head shell species found in mature heads are covalently cross-linked oligomers derived from the 42-kDa precursor during head shell maturation.