Comparative clinical and laboratory evaluation of the prophylactic capacity of ribavirin, amantadine hydrochloride, and placebo in induced human influenza type A

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.

Clinical studies with the Cendehill strain of attenuated rubella vaccine

The Saccharomyces cerevisiae killer factor glycoproteins killed the pathogen Torulopsis glabrata by a mechanism involving membrane damage. Some other yeast species were unaffected by these glycoprotein toxins.

Clinical and serologic effects of Alice strain live attenuated influenza A (H3N2) virus vaccine in an adult population

Alice strain live attenuated influenza A (H3N2) virus was evaluated in prison volunteers. By random double blind allocation, 94 volunteers received Alice strain vaccine (AS) intranasally and 97 received placebo. The vaccine was well tolerated, and there was no serious morbidity. The number, type, duration, and severity of symptoms was not significantly different between the vaccine and placebo groups. Seventy-five per cent of vaccines with initial HAI titers less than or equal to 1:8 had 4 fold or greater titer responses on day 30. Placebo recipients experienced no titer changes. The GMT among vaccinees increased from 23.5 prior to vaccination 59.7 30 days later. Surveillance activities failed to document influenza A (H3N2) infection in the volunteer population during a 6 month follow-up period. Additional studies on the protective effects of the vaccine are required before efficacy can be determined.

Alice strain live attenuated influenza (H3N2) vaccin in an elderly population

The clinical and antibody responses to Alice strain (AS) live attenuated influenza A (H3N2) vaccine and killed parenteral (KP) bivalent influenza vaccine were compared in a randomly allocated group of 150 elderly volunteers. AS recipients experienced more symptoms but these were mild and short in duration. Rhinitis occurred in 45% and pain at injection site in 25% of the AS and KP groups, respectively. Influenza A (H3N2) serum hemmaglutination inhibition titer responses were significantly higher in KP vaccinees; 95% of KP AND 60% OF AS recipients with initial titers smaller than or equal to 1:16 had fourfold or greater titer rises. KP induced significantly higher nasal neutralization titers but the proportion with fourfold or greater responses was not significantly different. Previous studies have shown poor correlations between antibody levels induced by live influenza vaccines and protection. Natural and/or challenge studies are needed before efficacy of influenza vaccines can be established.

Mode of action of colistin

The prophylactic efficacy of isoprinosine was evaluated in a double-blind fashion in volunteers challenged with two types of rhinovirus. In the rhinovirus 44 and 32 trials, each of 9 men received a placebo, and eight and 11 men received the drug, respectively. Oral isoprinosine, 6 g a day, was given for 2 days prior to intranasal challenge with 100 mean tissue culture infective doses of the virus and for 7 postchallenge days. In both trials the occurrence and severity of colds were greater in the placebo group, but the difference between the two groups was not significant. Higher antibody titers for both viruses and a greater number of rhinovirus 32 isolations were demonstrated in the drug group but without statistically significant differences. The prophylactic isoprinosine treatment may suppress the cold syndrome, but its effect was not convincingly apparent.

Antiviral effect of 3, 4-dihydro-1-isoquinolineacetamide hydrochloride in experimental human rhinovirus infection

Double-blind trials were conducted in volunteers to evaluate the efficacy of the prophylactic 3,4-dihydro-1-isoquinolineacetamide hydrochloride (DIQA) treatment against rhinovirus type 24 challenge. Ten men received a 7-day course of DIQA treatment and 11 men received a placebo. The intranasal viral challenge dose was 10 mean tissue culture infective doses. The oral administration of 1 g prechallenge and 2 g a day for 6 consecutive postchallenge days did not prevent the development of colds. Nine drug-treated men and 10 controls developed rhinovirus illness. However, the illnesses of the drug-treated men were mild. Rhinorrhea occurred less frequently and was more mild in the drug-treated group. The challenge virus was recovered from 80% of these subjects in both groups, but almost twice the number of challenge viruses were isolated from the controls than from the drug-treated men. The prophylactic DIQA therapy appears to suppress the cold syndrome and to reduce virus excretion, although its effect is marginal. Additional clinical trials are warranted to confirm the antirhinoviral effect of this drug.

In vitro effect of virazole against influenza viruses

The minimal inhibitory concentrations of Virazole against 32 mean tissue culture infective doses of three type A influenza strains including type A/England/42/72 (H3N2) and a type B strain in tissue culture were 0.1 and 0.05 mug/ml, respectively. The growth inhibition pattern by various Virazole concentrations of type A virus was similar to that of the type B virus. Virazole appears to be slightly more potent against the A/England/42/72 strain than are other antiinfluenzal agents.

Mucociliary function during experimentally induced rhinovirus infection in man

In conjunction with a controlled study of the effect of vitamin C on susceptibility to experimentally induced rhinovirus infections in man, we have conducted a study of nasal mucociliary function in the subjects volunteering for the study. In the 21 volunteers an average mucociliary flow rate (measured by the Quinlan tagged particle technique) of 7.5 mm/min was found in those with normal nasal morphology and 4.0 mm/min in those with abnormal nasal morphology. The rates decreased during infection in both groups but at different times after induction of infection. Ascorbic acid had no effect on either susceptibility to induced rhinovirus infection or mucociliary transport.

Evaluation of amantadine hydrochloride in the treatment of A2 influenzal disease

Amantadine hydrochloride is the first drug to show promise as a practical anti-influenza agent. Several studies demonstrating a prophylactic effect in volunteers with induced A2 disease as well as in patients during A2 outbreaks have created the impetus for therapeutic trials. The widespread A2 influenza epidemic that occurred early in 1968 provided the opportunity for therapeutic evaluation in the USA.A total of 197 prison inmates with proven influenza agreed to participate in the 10-day double-blind evaluation of amantadine (100 mg, twice daily). Onset of therapy was approximately 20 hours after first subjective awareness of illness.Assessment of drug effectiveness was based on rapidity of resolution of illness. There was a significant increase in the number of drug-treated as against placebo patients in the "rapid resolver" group whereas individuals receiving placebo dominated the "slow resolver" group. Analysis of febrile responses indicated that amantadine-treated patients had significantly more rapid defervescence. Virus isolation studies revealed etiologically related virus in 90% of all volunteers during the first 5 days of therapy. It was apparent that clinical improvement was not correlated with disappearance of the virus. Nevertheless, the trials conducted during the influenza season of early 1968 indicated the therapeutic effect of amantadine hydrochloride. Administration of 100 mg, twice daily, for 10 days did not cause any adverse effects.

Antibody Response in Respiratory Secretions of Volunteers Given Live and Dead Influenza Virus

The nature of the neutralizing antibody response in respiratory secretions to influenza virus has been compared in two groups of human volunteers, one given live virus via the respiratory tract and the other given dead virus parenterally. The “live-virus group” showed an antibody response in sputum and nasal washing that was significantly greater in magnitude and longer in duration than it was in the “dead-virus group.” There was no difference in the antibody response in saliva. In volunteers who were inoculated with live virus but showed no serum antibody rise, there was, nevertheless, a rise in sputum or nasal washing antibody. These results indicate that local infection is superior to parenteral immunization in inducing antibody in respiratory secretions.