thiobarbituric-acid and Influenza--Human

Antibodies to neuraminidase (NA), the second most abundant surface protein on influenza virus, contribute toward protection against influenza. The traditional thiobarbituric acid (TBA) method to quantify NA inhibiting antibodies is cumbersome and not suitable for routine serology. An enzyme-linked lectin assay (ELLA) described by Lambre et al. (1990) is a practical alternative method for measuring NA inhibition (NI) titers. This report describes optimization of the ELLA for measuring NI titers in human sera against influenza A viruses, using H6N1 and H6N2 viruses as antigens. The optimized ELLA is subtype-specific and reproducible. While the titers measured by ELLA are somewhat greater than those measured by a miniaturized TBA method, seroconversion rates are the same, suggesting similarity in assay sensitivity under these optimized conditions. The ELLA described in this report provides a practical format for routine evaluation of human antibody responses to NA.

Topics: Animals; Antibodies, Viral; Antibody Formation; Cross Reactions; Ferrets; Humans; Immunoenzyme Techniques; Influenza A virus; Influenza Vaccines; Influenza, Human; Lectins; Neuraminidase; Sigmodontinae; Thiobarbiturates; Viral Proteins

Antibodies to neuraminidase (NA) contribute to protection during influenza virus infection, but NA inhibition (NI) titers are not routinely analyzed in vaccine trials. One reason is the cumbersome nature of the conventional thiobarbituric acid (TBA) NI assay, which uses chemical methods to quantify free sialic acid following incubation of NA with substrate in the presence of serum. In addition, the assay is complicated by the need to use virus of a hemagglutinin (HA) subtype novel to the host to detect NA-specific antibodies only.. Our primary objectives were to miniaturize the colorimetric NI assay to a format suitable for quantitative analysis of large numbers of samples, and validate the specificity and sensitivity of the miniaturized format with ferret and human sera. An additional aim was to use reverse genetics to construct HA-mismatched viral reagents bearing NA of recent influenza A vaccine strains and H6 HA.. Analysis of ferret antisera by the miniaturized assay demonstrated sensitivity and specificity comparable with the conventional assay. Similar increases in the NI titers in sera from vaccinated human volunteers were measured in miniaturized and conventional assays. Inactivated and live-attenuated vaccines increased NI titers against a given subtype at approximately the same rate.. The reagents and miniaturized format of the TBA method described here provide a platform for practical serological monitoring of functional antibodies against NA.

Topics: Animals; Antibodies, Viral; Antigens, Viral; Colorimetry; Ferrets; Humans; Immunization; Influenza A virus; Influenza Vaccines; Influenza, Human; Miniaturization; Neuraminidase; Orthomyxoviridae Infections; Sensitivity and Specificity; Thiobarbiturates

It was established that viral particles, like low-density lipoproteins (LDLP), when subjected to some modification changes, lost their ability to be internalized by tissue somatic cells and acquired tropism to macrophage cells. The data, obtained by us by using the polymerase chain reaction (PCR) method, made it possible to assert that atherosclerotic plaques, isolated from vessels of patients with ischemic heart disease (IHD) who underwent coronary bypass, contained RNA of the A(HINI) and AH3N3) influenza viruses. Whereas, the vessel portions, undamaged by atherosclerosis, did not contain any genetic substances of influenza viruses. It was for the first time that an experimentally supported understanding was expressed on that the atherosclerotic plaques serve as a "reservoir" for influenza viruses. It is also suggested that the mentioned plaques can be the carriers of influenza viruses for a long time, thus, prolonging the persistent form of influenza infection in the human body.

Topics: Aged; Animals; Arteriosclerosis; Coronary Artery Bypass; Coronary Artery Disease; Coronary Vessels; Humans; Influenza A virus; Influenza, Human; Lipid Peroxidation; Lung; Malondialdehyde; Mice; Middle Aged; Myocardial Ischemia; Polymerase Chain Reaction; RNA, Viral; Spectrophotometry; Thiobarbiturates; Time Factors; Tropism