Delayed type IV hypersensitivity reaction to porcine acellular dermal matrix masquerading as infection resulting in multiple debridements.

INTRODUCTION: Delayed type IV hypersensitivity reactions are well established in the surgical setting with respect to external exposure via topical antibiotics and internal exposure via synthetic materials. In contrast, biologic matrix is derived from decellularized human or animal tissues and is consequently believed to elicit a minimal host inflammatory response. OBJECTIVE: We report a case of delayed type IV hypersensitivity reaction secondary to a biologic comprised of porcine-derived acellular dermal matrix, [Strattice™]. CONCLUSIONS: While biologic matrix is often preferred over synthetic mesh due to its decreased risk for infection, this case emphasizes that potential for hypersensitivity to the material persists. Type IV hypersensitivity reactions should be included in the differential diagnosis for suspected post-operative infections.

DNA binding by Kaposi's sarcoma-associated herpesvirus lytic switch protein is necessary for transcriptional activation of two viral delayed early promoters.

Kaposi's sarcoma-associated herpesvirus (KSHV; also known as human herpesvirus-8) establishes latent and lytic infections in both lymphoid and endothelial cells and has been associated with diseases of both cell types. The KSHV open reading frame 50 (ORF50) protein is a transcriptional activator that plays a central role in the reactivation of lytic viral replication from latency. Here we identify and characterize a DNA binding site for the ORF50 protein that is shared by the promoters of two delayed early genes (ORF57 and K-bZIP). Transfer of this element to heterologous promoters confers on them high-level responsiveness to ORF50, indicating that the element is both necessary and sufficient for activation. The element consists of a conserved 12-bp palindromic sequence and less conserved sequences immediately 3' to it. Mutational analysis reveals that sequences within the palindrome are critical for binding and activation by ORF50, but the presence of a palindrome itself is not absolutely required. The 3' flanking sequences also play a critical role in DNA binding and transactivation. The strong concordance of DNA binding in vitro with transcriptional activation in vivo strongly implies that sequence-specific DNA binding is necessary for ORF50-mediated activation through this element. Expression of truncated versions of the ORF50 protein reveals that DNA binding is mediated by the amino-terminal 272 amino acids of the polypeptide.