The comparative prophylactic effectiveness of oral treatment with ribavirin (1-beta-D-ribofuranosyl-1,2,4,triazole-3-carboxamide; virazole) and amantadine hydrochloride against artificially induced infection with influenza A virus was evaluated in 29 seronegative men who received ribavirin capsules (200 mg) three times daily, placebo capsules three times daily, or amantadine capsules (100 mg) twice daily. Medication was started two days before the inoculation of 2 X 10(4) 50% tissue culture infective doses of A University of Maryland/2/74 (H3N2) influenza virus and was continued for eight days after challege. Nine of the 10 subjects who received ribavirin, eight of the nine subjects who received placebo, and six of the 10 subjects who received amantadine developed influenzal illness. Significantly less virus was isolated from the amantadine-treated group than from the placebo-treated or the ribavirin-treated group. Antibody responses of the ribavirin-treated and placebo-treated groups were quite similar to each other; however, prophylactic treatment with amantadine significantly reduced titers of serum antibody and febrile responses. In a separate clinical trial involving challenge with A/Dunedin/73 (H3N2) influenza virus, ribavirin also failed to show prophylactic effectiveness.

Twenty-one healthy, susceptible adult male volunteers were enrolled in a doubleblind study designed for evaluation of the prophylactic efficacy of ascorbic acid (3 g daily) in induced rhinovirus 44 infection of the upper respiratory tract. While in continuous isolation, 11 men received 1 g of ascorbic acid three times daily, and 10 men received a placebo for two weeks, after which an intranasal inoculum containing 100 TCID 50 of rhinovirus 44 was administered. Each man continued to receive the same dose of medication for one week after the viral challenge. All participants subsequently developed typical illness due to rhinovirus. Similar levels of antibody in serum, nasal washings, and sputum developed in all subjects. Nasal shedding of virus and the flow of the nasal mucociliary blanket were unaffected by the ingestion of ascorbic acid. No prophylactic benefit was demonstrated from the daily ingestion of 3 g of ascorbic acid in induced rhinovirus 44 infection in man.

Protein-bound polysaccharide K (PSK) increased the 5-year disease-free survival rate and reduced the risk of recurrence in a randomised, controlled study for stage II and III colorectal cancer. In order to elucidate the disease-free survival benefits with PSK and what immunological markers could indicate a PSK responder, serial changes in immunological parameters were monitored in the study. PSK decreased the mean serum immunosuppressive acidic protein (IAP) level, and increased the mean population of natural killer (NK) cells compared with the controls. The 5-year disease-free and overall survival rate for patients with serum IAP values ≤500 μg ml -1 , which represents the normal value, were 75.5% (95% CI: 66.8-84.2%; p=0.016) and 85.1% (95% CI: 77.9-92.3%; p=0.032), respectively, in the PSK group compared with 57.5% (95% CI: 43.3-71.6%) and 70.2% (95% CI: 57.1-83.3%) in the control group. In patients with NK cell population ≥8% at 3 months after surgery, PSK conferred a significantly better (p=0.038) 5-year disease-free survival (86.7%; 95% CI: 74.5-98.8%) compared to the control group (60.0%; 95% CI: 29.6-90.4%).In the proportional hazards model, the presence of regional metastases (relative risk, 3.595; 95% CI: 1.518 to 8.518; p=0.004) and omission of PSK treatment (relative risk, 3.099; 95% CI: 1.202 to 7.990; p=0.019) were significant indicators of recurrence. PSK acts as an immunomodulatory activity and biochemical modulator in stage II or III colorectal cancer. Pre-operative serum IAP values ≤500 μg ml -1 and an NK cell population ≥8% at 3 months after surgery are possible PSK response predictors.

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