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[Changes in affinity to mucoprotein receptors of influenza A2-strains after mouse adaptation (author's transl)]
Abstract:
The aim of the study was to establish the relationship between mouse-virulence and affinity of influenza A2-viruses to certain naturally occurring mucoprotein receptor substances. Mouse adaptation of 4 egg adapted cloned H2N2-strains, sensitive to RDE-resistant horse serum inhibitor (PSI), and RDE-sensitive chick serum inhibitor (HSI) in the haemagglutination inhibition and neutralisation test (E+-strains) resulted in mouse virulent strains with diminished PSI-sensitivity (M+-strains, (Table 2). Sensitivity to HSI and to the RDE sensitive fraction of PSI was comparatively less affected (Tables 3, 4). In contrast to the original egg-adapted strains there were only minor differences in inhibitor sensitivity between different M+-strains (Tables 2, 3). 4 mouse virulent strains, derived from 3 egg-adapted strains resistant to PSI and HSI (E--strains), either remained unchanged (2) or gained inhibitor sensitivity (2), (Tables 2, 3). Mouse adapted strains resistant to HSI and PSI could also be selected from M+-strains by passage with PSI in embryonated eggs. In general, properties related to mucoprotein affinity of these strains correspond to those of M--strains derived from E--strains. During selection of M--strains by passage with PSI, strains insensitive to PSI but with considerable residual sensitivity to HSI were encountered (Tables 5, 6). Evidence is presented, that strains of intermediate sensitivity can consist of essentially homogenous populations (Figure 1). While egg adapted inhibitor-sensitive strains showed a high, insensitive strains a low affinity to the human erythrocyte membrane, the reverse was true for mouse adapted strains (Figure 2, Talbes 7, 8). On the other hand all inhibitor-insensitive strains proved to have a higher affinity to the mouse and bovine erythrocyte membrane than sensitive strains (Table 9). PSI-sensitivity of one PSI-sensitivity of one PSI-sensitive Hong Kong/1/68 (H3N2)-strain did not change during mouse adaptation. In a second line, passed in suckling mice, PSI-sensitivity decreased below HSI-sensitivity. Changes in respect to erythrocyte affinity were similar to those of H2-strains.
Insights
Influenza A2 virus adaptation to mice alters its affinity for mucoprotein receptors, impacting virulence. Mouse-adapted strains show reversed erythrocyte membrane affinity compared to egg-adapted strains, influencing viral binding properties.
Area of Science:
- Virology
- Molecular Biology
- Immunology
Context:
- Influenza A2 viruses exhibit varying sensitivities to host-derived inhibitors like RDE-resistant horse serum inhibitor (PSI) and RDE-sensitive chick serum inhibitor (HSI).
- Egg-adapted strains (E+-strains) differ in inhibitor sensitivity from strains adapted to mouse virulence (M+-strains).
Purpose:
- To investigate the relationship between mouse virulence and the affinity of influenza A2 viruses for mucoprotein receptor substances.
- To characterize changes in inhibitor sensitivity and erythrocyte membrane affinity during influenza virus adaptation to mice.
Summary:
- Mouse adaptation of H2N2 strains resulted in mouse-virulent strains with diminished PSI-sensitivity, while HSI sensitivity was less affected.
- Egg-adapted strains showed high affinity for human erythrocyte membranes, whereas mouse-adapted strains exhibited higher affinity for mouse and bovine erythrocyte membranes.
- Adaptation processes can lead to selection of strains with altered inhibitor sensitivities and reversed erythrocyte binding preferences.
Impact:
- Findings elucidate how viral adaptation influences receptor binding, potentially affecting host tropism and pathogenesis.
- Understanding these changes is crucial for developing effective antiviral strategies and vaccines.
- The study highlights the dynamic nature of viral evolution in response to host environments.