HIV-1 Tat modulates invasion by a bacterial enteric pathogen into a human intestinal cell line.
OBJECTIVE
To explore the possibility that an HIV-1 gene product may modulate entry of an invasive enteric pathogen into a terminally differentiated human intestinal cell line. HIV-1 Tat was selected for investigation because of its unique ability to cross cell membranes.


METHODS
After transient transfection of HT29-C1 cells with plasmids containing HIV-1 long terminal repeat (LTR)-lacZ plus a Tat expression cassette, or with a pSR-lacZ control plasmid, bacterial invasion assays were performed on both groups of cells utilizing a clinical Salmonella isolate. Assays were performed concurrently on a control group of non-transfected cells. A second series of experiments compared bacterial invasion into cells transfected with the Tat expression vector alone versus cells transfected with either an isogenic expression vector that did not make Tat, or with pSR-lacZ. Finally, the ability of exogenous Tat protein to transactivate an HIV-1 LTR-chloramphenicol acetyltransferase (CAT) plasmid which had been transfected into HT29-C1 cells and to modulate Salmonella invasion was also assessed.


RESULTS
HT29-C1 cells transfected with a Tat expression vector, either alone or in combination with another plasmid, were significantly less susceptible to bacterial invasion than cells that either did not undergo transfection, were transfected with an otherwise isogenic expression vector without Tat, or transfected with an unrelated plasmid. Duplicate experiments also demonstrated that exogenous purified Tat protein transactivated an HIV-1 LTR-CAT plasmid which had been transfected into HT29-C1 cells and inhibited Salmonella invasion compared with unexposed cells.


CONCLUSIONS
HIV-1 Tat inhibits Salmonella invasion of a human enterocyte cell line whether the protein is expressed intracellularly or provided exogenously.
Mayer
H B
HB
Division of Infectious Diseases, New England Deaconess Hospital, Boston, MA 02115, USA.
Wanke
C A
CA
Du
B
B
Hammer
S M
SM
Terwilliger
E F
EF
D000818:Animals; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D004789:Enzyme Activation; D015696:Gene Products, tat / Q000096:biosynthesis* / Q000235:genetics; D018014:Gene Transfer Techniques; D015497:HIV-1; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000382:microbiology* / Q000821:virology; D012475:Salmonella / Q000472:pathogenicity*; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D054322:tat Gene Products, Human Immunodeficiency Virus; D015500:Chloramphenicol O-Acetyltransferase