Research: ASF virus rapidly attacks pig immune system
The very high death toll amongst pigs infected with African Swine Fever virus (ASFv) in pigs could be very well related to the early loss of immune cells.
That conclusion was shared by a research team of the UK-based The Pirbright Institute in a publication in the journal Discovery Immunology.
In a news release shared by the institute, the researchers explained that the rapid depletion of immune cells that are key to sensing and controlling infections in infected pigs may explain why vaccines remain elusive and the disease is almost always fatal.
Mimicking ASF infection routes
The team explained how ASFv quickly disrupts immune responses during the earliest stages of infection. The team examined early virus spread and immune cell dynamics following infection through routes that closely mimic natural exposure.
In the news article, Dr Priscilla Tng commented, “The virus was detected in lymphoid tissues associated with the mouth and respiratory tract within one to three days of infection before spreading systemically. By the time clinical signs such as fever and lethargy appeared, often within a week, critical immune cell populations were already being depleted.”
Widespread loss of pig immune cells
The news article continued to write that the researchers observed widespread loss and dysfunction of immune cells essential for mounting effective defences, including T-cells, dendritic cells, natural killer cells and macrophages.
Dr Tng was quoted to say, “Many of these cells showed signs of apoptosis, or programmed cell death, suggesting that the virus not only infects immune cells directly but also triggers their destruction.”
Early loss of key immune cells
Notably, the study showed the collapse of the “innate-adaptive interface” – the coordinated interaction between early, non-specific immune responses and the longer-lasting adaptive response. Cells that normally connect these 2 arms of immunity, such as dendritic cells and gamma-delta (γδ) T-cells, were rapidly depleted or rendered dysfunctional.
Dr Tng added, “This early loss of key immune cell populations helps explain why pigs infected with highly virulent ASFv rarely survive.”
The findings suggest the speed and breadth of immune disruption caused by virulent ASFv strains may be a defining feature of acute disease. Understanding which immune cells are targeted first – and how this varies between viral strains – could hold the key to the design of future vaccines.
Different ASFv isolates
In the news article, the research team concluded, “Our findings highlight the need to investigate the innate-adaptive axis further with different ASFv isolates of varying virulence to determine if this immune imbalance is a defining feature of acute ASFv infection.”
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