Highly pathogenic or low pathogenic avian influenza virus subtype H7N1 infection in chicken lungs: small differences in general acute responses

ABSTRACT: Avian influenza virus can be divided into two groups, highly pathogenic avian influenza virus (HPAI) and low pathogenic avian influenza virus (LPAI) based on their difference in virulence. To investigate if the difference in clinical outcome between LPAI and HPAI in chickens is due to immunological host responses in the lung within the first 24 hours post infection (hpi), chickens were infected with LPAI or HPAI of subtype H7N1. Virus was found in the caudal and cranial part of the lung. With LPAI, virus was localised around the intrapulmonary bronchus and secondary bronchi. In sharp contrast, HPAI was detected throughout the whole lung. However, based on viral RNA levels, no quantitative difference was observed between LPAI and HPAI infected birds. In infected areas of the lungs, an influx of CD8α+ cells as well as KUL01+ macrophages and dendritic cells (DC) occurred as fast as 8 hpi in both infected groups. No major difference between LPAI and HPAI infected birds in the induction of cytokines and interferons at mRNA level in lung tissue was found.In conclusion, the differences in lethality for chickens infected with LPAI or HPAI could be ascribed to difference in location of the virus. However similar amounts of viral RNA, similar cytokine mRNA levels, and similar influxes of CD8α+ and KUL01+ macrophages and DC were found between HPAI and LPAI in the lungs. A cytokine storm at mRNA level as described for mammals was not observed in the lungs of HPAI infected birds within 24 hpi.     

Improving laccase catalyzed cross-linking of whey protein isolate and their application as emulsifiers

Whey protein isolate (WPI) was chemically modified by vanillic acid in order to enhance its cross-linkability by laccase enzyme. Incorporation of methoxyphenol groups created reactive sites for laccase on the surface of the protein and improved the efficiency of cross-linking. The vanillic acid modified WPI (Van-WPI) was characterized using MALDI-TOF mass spectrometry, and the laccase-catalyzed cross-linking of Van-WPI was studied. Furthermore, the vanillic acid modification was compared with the conventional approach to improve laccase-catalyzed cross-linking by adding free phenolic compounds. A small extent of the vanillic acid modification significantly improved the cross-linkability of the protein and made it possible to avoid color formation in a system that is free of small phenolic compounds. Moreover, the potential application of Van-WPI as emulsifier and the effect of cross-linking on the stability of Van-WPI emulsion were investigated. The post-emulsification cross-linking by laccase was proven to enhance the storage stability of Van-WPI emulsion.     

A century of transformation: fire regime transitions from 1919 to 2019 in southeastern British Columbia,Canada

Context

In fire-excluded forests across western North America, recent intense wildfire seasons starkly contrast with fire regimes of the past. The last 100 years mark a transition between pre-colonial and modern era fire regimes, providing crucial context for understanding future wildfire behavior.

Objectives

Using the greatest time depth of digitized fire events in Canada, we identify distinct phases of wildfire regimes from 1919 to 2019 by evaluating changes in mapped fire perimeters (>?20-ha) across the East Kootenay region (including the southern Rocky Mountain Trench), British Columbia.

Methods

We detect transitions in annual number of fires, burned area, and fire size; explore the role of lightning- and human-caused fires in driving these transitions; and quantify departures from historical fire frequency at the regional level.

Results

Relative to historical fire frequency, fire exclusion has created a significant fire deficit in active fire regimes, with a minimum of 1–10 fires missed across 46.4-percent of the landscape. Fire was active from 1919 to 1939 with frequent and large fire events, but the regime was already altered by a century of colonization. Fire activity decreased in 1940, coinciding with effective fire suppression influenced by a mild climatic period. In 2003, the combined effects of fire exclusion and accelerated climate change fueled a shift in fire regimes of various forest types, with increases in area burned and mean fire size driven by lightning.

Conclusions

The extent of fire regime disruption warrants significant management and policy attention to alter the current trajectory and facilitate better co-existence with wildfire throughout this century.

Graphical abstract