Three lectins with different sugar binding specificities were investigated for anti-viral activity against human parainfluenza virus type 2 (hPIV-2). The lectins, concanavalin A (Con A), lens culinaris agglutinin (LCA) and peanut agglutinin (PNA), inhibited cell fusion and hemadsorption induced by hPIV-2. Virus nucleoprotein (NP) gene synthesis was largely inhibited, but fusion (F) and hemagglutinin-neuraminidase (HN) gene syntheses were not. An indirect immunofluorescence study showed that Con A inhibited virus NP, F and HN protein syntheses, but LCA did not completely inhibit them, and that PNA inhibited only NP protein synthesis. Using a recombinant green fluorescence protein-expressing hPIV-2, without matrix protein (rghPIV-2ΔM), it was found that virus entry into the cells was not completely prevented. The lectins considerably reduced the number of viruses released compared with that of virus infected cells. The lectins bound to cell surface within 10 min, and many aggregates were observed at 30 min. Con A and LCA slightly disrupted actin microfilaments and microtubules, but PNA had almost no effect on them. These results indicated that the inhibitory effects of the lectins were caused mainly by the considerable prevention of virus adsorption to the cells by the lectin binding to their receptors.

ObjectivesMethotrexate (MTX) is administered once or thrice weekly to patients with rheumatoid arthritis (RA). Even though RA continually progresses, MTX is not administered daily. Therefore, we investigated whether the daily administration of a low dose of MTX inhibits the progression of arthritis in collagen‐induced arthritis (CIA) rats.MethodsMethotrexate was orally administered once weekly, thrice weekly and once daily to CIA rats, and arthritis scores were measured.Key findingsWhen the same dose of MTX was administered, the exacerbation of arthritis was inhibited significantly more in the once‐daily group than in the other groups. When the dose in the once‐daily group was reduced to one‐fourth that of the current standard dosing method, arthritis scores were markedly lower in the once‐daily group than in the once and thrice‐weekly groups.ConclusionsThe daily administration of a low dose of MTX not only maintained normal levels that estimated adverse effects but also suppressed the progression of arthritis significantly more than the current standard dosing method. The results indicate that the reconsideration of dosing schedules based on the characteristics of MTX will lead to more effective RA therapy than that currently used in clinical practice.

Lactoferrin (Lf) is a multifunctional protein that has inhibitory activity against microorganisms. In this study, the effects of Lf on the growth of human parainfluenza virus type 2 (hPIV-2) in LLCMK 2 cells were investigated. Lf inhibited cell fusion and hemadsorption induced by hPIV-2. However, virus RNA synthesis was only slightly inhibited by Lf. In addition, indirect immunofluorescence study showed that virus protein syntheses were not completely inhibited by Lf. Using a recombinant, green fluorescence protein-expressing hPIV-2 (rghPIV-2), it was found that virus entry into cells were considerably inhibited by Lf, but cell-to-cell spread was not inhibited. The number of viruses produced by the cells were determined, and it was found that Lf reduced the number of released viruses to about 1/300 compared with that of positive control. Lf bound to cell surface within 10 min at early phase of infection, it assembled gradually, and many aggregates were observed at 120 min. These results indicated that Lf considerably inhibited virus adsorption to the surface of the cells by binding * To whom correspondence should be addressed: Department of Microbiology, Graduate School of Clinical Nutrition, Suzuka University of Medical Science, 1001-1 Kishioka, Suzuka, Mie 510-0293, Japan. Tel.: +81-59-383-8991; Fax: +81-59-383-9666; E-mail: komada@suzuka-u.ac.jp to the cell surface and prevented hPIV-2 infection.