Summary auto-generated
This study demonstrates that serum albumin inhibits echovirus 7 (EV7) infection by blocking viral uncoating, a critical early step in the infection cycle. Researchers used bovine serum albumin (BSA) and human serum albumin (HSA) at physiological concentrations (1-2%) and showed that both effectively prevented EV7-induced cell damage. The inhibition was specific to EV7, as poliovirus remained unaffected. Using multiple approaches—including cold-synchronized growth analysis, sucrose gradient centrifugation, and antigen production assays—the authors confirmed that albumin blocks the conversion of intact 160S viral particles to 135S altered A-particles and 80S empty capsids. The blockade was rapid, reversible when albumin was removed within 2 hours post-infection, and could still be applied 30 minutes after virus adsorption. Notably, the inhibition persisted when followed by rhodanine, a known uncoating inhibitor, confirming that albumin targets the uncoating process specifically. The authors propose that physiological albumin concentrations in serum and interstitial fluid may function as an extracellular determinant limiting EV7 tropism in vivo, potentially protecting tissues from infection.
Key findings
- Serum albumin inhibits echovirus 7 infection specifically by blocking viral uncoating, the conversion of 160S intact particles to 135S altered A-particles
- Albumin inhibition is rapid, reversible within 2 hours post-infection, and effective even when added 30 minutes after viral adsorption
- The inhibitory effect is species- and virus-specific: multiple albumin preparations block EV7 but not poliovirus, while non-albumin proteins have no effect
- Physiological concentrations of albumin (1-2%) in serum and interstitial fluids may limit echovirus tropism in vivo as an extracellular defense factor
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Abstract
Echoviruses induce a wide spectrum of diseases in man, the most severe being meningitis. In neonates, however, a severe systemic infection can be observed, leading to death. Serum albumin is the most abundant protein in plasma and most interstitial fluids, and its functions include osmoregulation and transport and delivery of hydrophobic molecules such as fatty acids and steroids. The results of cold- synchronized one-step growth analysis of echovirus 7 infection and sucrose-gradient analysis of A-particles suggest that physiological concentrations of albumin block echovirus 7 infection by inhibiting uncoating. The blockage was reversible and was still effective when albumin was added 30 min after virus adsorption. Inhibition of uncoating was confirmed by using rhodanine, a known specific inhibitor of echovirus uncoating. After removal of the albumin blockage, addition of rhodanine perpetuated the inhibition. Serum and interstitial albumin concentrations may limit echovirus infection in vivo and thereby act as an extracellular determinant for echovirus tropism.