Mucosal vaccination against influenza: protection of pigs immunized with inactivated virus and ether-split vaccine.

Effective vaccinations against swine influenza reduce the economic loss of pig industries, and also may minimize the possibility of emergence of new pandemic viruses, since pigs are intermediate hosts to generate reassortant viruses among avian and mammalian influenza viruses. In this study, we showed that intranasal immunization of pigs with formalin-inactivated or ether-split influenza vaccine (A/Aichi/2/68) induced virus-specific IgG, IgM, and IgA antibodies in their nasal secretions and sera, resulting in complete protection from virus challenge. Antibody response to the challenge virus was not observed in the immunized pigs, suggesting that the replication of the virus in the primary targets, respiratory epithelial cells, was inhibited. The present results indicate that intranasal immunization of pigs with inactivated vaccines is effective to control swine influenza, and also provide a good model, as well as a mouse model, to evaluate an intranasal application of influenza vaccine for humans.

Precursor genes of future pandemic influenza viruses are perpetuated in ducks nesting in Siberia.

Influenza A viruses of different subtypes were isolated from fecal samples of ducks in their nesting areas in Siberia in summer from 1996 to 1998. Phylogenetic analysis of the NP genes of the isolates in Siberia and those in Hokkaido, Japan on their flyway of migration from Siberia to the south in autumn revealed that they belong to the Eurasian lineage of avian influenza viruses. It is noted that the genes of the isolates in Siberia are closely related to those of H5N1 influenza virus strains isolated from chickens and humans in Hong Kong in 1997 as well as to those of isolates from domestic birds in southern China. The results indicate that influenza viruses perpetuated in ducks nesting in Siberia should have contributed genes in the emergence of the H5N1 virus in Hong Kong. Vaccine prepared from avirulent A/duck/Hokkaido/4/96 (H5N3) influenza virus was potent enough to protect mice from challenge with lethal dose of the pathogenic H5N1 virus [19]. Intensive surveillance study of aquatic birds especially in Siberia is, therefore, stressed to provide information on the future pandemic influenza virus strains and for vaccine preparation.

The effects of isosorbide dinitrate on exercise-induced ST-segment elevation at the infarcted area in old myocardial infarction.

To clarify the clinical significance and therapeutic implication of exercise-induced ST elevation at the infarcted area in old myocardial infarction (OMI), 30 patients with exercise-induced ST elevation underwent treadmill exercise testing. The patients with transient perfusion defects at the infarcted area on thallium-201 stress myocardial scintigraphy (group I: n = 12) revealed a decreased rate of ST elevation expressed as delta ST/delta HR X 10(2) after 10 mg of isosorbide dinitrate (ISDN), compared to the results of treadmill exercise testing under no medication (3.1 +/- 2.5 vs. 4.7 +/- 2.6, p less than 0.001). Exercise capacity and anginal threshold were improved after ISDN in group I. In contrast, the patients without transient perfusion defects (group II: n = 18) revealed an increased rate of ST elevation after ISDN (2.4 +/- 1.1 vs. 2.0 +/- 0.8, p less than 0.05). It is concluded from the above results that if exercise-induced ST elevation at the infarcted area reflects transient myocardial ischemia, ISDN can decrease it by its anti-anginal effect. Additionally, treadmill exercise testing with ISDN is a useful means of clarifying the underlying pathophysiology and management in OMI cases with this effect on exercise-induced ST elevation at the infarcted area.