Three pools were made to avoid excessive relative dilution of individual peptides. Pool #1 additionally included the matrix protein epitope GILGFVFTL (a human but not a murine epitope). A single large pool of listeriolysin peptides (15-mers overlapping by 11) was the kind gift small molecule library screening of Cerus Corporation (Concord, CA, USA). The study was reviewed and supervised by a local institutional review board (Massachusetts General
Hospital) and Biosafety Committee (Harvard Medical School Committee on Microbiological Safety). The study was also reviewed and approved by the NIH/NIAID Prevention Science Review Committee, an independent Data Safety Monitoring Board (DSMB) (three physicians with expertise in listeriosis, clinical trials and enteric infections), an NIH physician medical monitor, and the US Food and Drug Administration (FDA, BB IND #12760). All of these groups appreciated the goals of the study to be the further evaluation of safety and physiological and immunological responses to listerial vectors, and selleckchem not as a prelude to the development of a new influenza vaccine, and found it ethically acceptable. All subjects provided written informed consent to participate. Healthy men and women, aged 18–45 years old, were recruited by advertising and
underwent a complete screening physical exam and standard laboratory procedures, as described previously (9). Potential volunteers must have previously tolerated a course
of therapy with penicillin or ampicillin. In addition to standard clinical screening laboratories, volunteers were required to have normal iron studies, normal liver function tests, and a pre-study stool sample that was negative Pregnenolone for routine enteric pathogens, ova and parasites, as well as L. monocytogenes. Subjects were not HLA haplotyped, as this would have been prohibitively limiting and expensive. Subjects were also not screened in any way for previous exposure to L. monocytogenes or for previous influenza exposure, expecting that most would have been previously exposed, especially to influenza. L. monocytogenes are ubiquitous organisms, despite best food safety efforts. It was hypothesized that existing immunity to influenza or listerial antigens might be “boosted” by this oral vaccination. Frozen inocula (0.9% w/v saline with 20% glycerol, 1.3 mL/vial) were produced utilizing good manufacturing practices by contract with the Walter Reed Army Institute of Research Pilot Bioproduction Facility (Silver Spring, MD, USA), a requirement of the funder. Vials were thawed at 4°C for 15 min and diluted with 0.9% saline for administration to volunteers in 30 mL. Based on spread plate cultures prior to freezing and multiple assessments of thawed vials, each inoculation of a given number of live colony forming units (CFU) also contained approximately two-fold greater dead organisms, or residual thereof.