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Influenza Other Respir Viruses. 2012 Mar;6(2):127-35. doi: 10.1111/j.1750-2659.2011.00283.x. Epub 2011 Aug 29.

Contribution of murine innate serum inhibitors toward interference within influenza virus immune assays.

Author information

1
Division of Basic Biomedical Sciences, University of South Dakota, Vermillion, SD 57069-2390, USA.

Abstract

BACKGROUND:

Prior to detection of an antibody response toward influenza viruses using the hemagglutination inhibition assay (HAI), sera are routinely treated to inactivate innate inhibitors using both heat inactivation (56°C) and recombinant neuraminidase [receptor-destroying enzyme (RDE)].

OBJECTIVES:

We revisited the contributions of innate serum inhibitors toward interference with influenza viruses in immune assays, using murine sera, with emphasis on the interactions with influenza A viruses of the H3N2 subtype.

METHODS:

We used individual serum treatments: 56°C alone, RDE alone, or RDE + 56°C, to treat sera prior to evaluation within HAI, microneutralization, and macrophage uptake assays.

RESULTS:

Our data demonstrate that inhibitors present within untreated murine sera interfere with the HAI assay in a manner that is different from that seen for the microneutralization assay. Specifically, the γ class inhibitor α(2) -Macroglobulin (A2-M) can inhibit H3N2 viruses within the HAI assay, but not in the microneutralization assay. Based on these findings, we used a macrophage uptake assay to demonstrate that these inhibitors can increase uptake by macrophages when the influenza viruses express an HA from a 1968 H3N2 virus isolate, but not a 1997 H3N2 isolate.

CONCLUSIONS:

The practice of treating sera to inactivate innate inhibitors of influenza viruses prior to evaluation within immune assays has allowed us to effectively detect influenza virus-specific antibodies for decades. However, this practice has yielded an under-appreciation for the contribution of innate serum inhibitors toward host immune responses against these viruses, including contributions toward neutralization and macrophage uptake.

PMID:
21883963
PMCID:
PMC3235232
DOI:
10.1111/j.1750-2659.2011.00283.x
[Indexed for MEDLINE]
Free PMC Article

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