The pathogen is apparently able to infect insects as well

Jan 21, 2014 10:50 GMT  ·  By
The TRSV virus can jump hosts, from plants to insects, and infect the regular honeybees, potentially leading to their decline
   The TRSV virus can jump hosts, from plants to insects, and infect the regular honeybees, potentially leading to their decline

Finding viruses that can move from infecting plants to infecting insects or mammals is extremely rare, but this is precisely what investigators at the US Department of Agriculture's (DOA) Agricultural Research Service (ARS) Laboratory in Beltsville, Maryland found in a recent study of honeybees.

The presence of this viral pathogen, called Tobacco Ringspot Virus (TRSV), in the bodies of honeybees came as a surprise to researchers. Details of their analyses were published in the latest online issue of the American Society of Microbiology's (ASM) open-access journal mBio.

This investigation was conducted in order to gain more insight into the factors that contribute to global bee populations decline. This drop in numbers first started being recorded a few years ago, and has been going on ever since, with areas in the United States and the United Kingdom being the worst-affected, PhysOrg reports.

The team set off by screening a number of honeybees for frequent and rare viruses, using conventional testing methods. This “resulted in the serendipitous detection of [TRSV], and prompted an investigation into whether this plant-infecting virus could also cause systemic infection in the bees,” explains ARS expert and study author Yan Ping Chen.

“The results of our study provide the first evidence that honeybees exposed to virus-contaminated pollen can also be infected and that the infection becomes widespread in their bodies,” adds Ji Lian Li, the lead author of the study, and a scientist at the Chinese Academy of Agricultural Science, in Beijing.

Chen explains that previous investigations have already established that honeybees (Apis mellifera) are able to carry TSRV from one plant to the next. However, microbiologists until now thought that the bees were simply transmission vectors for the virus, not hosts.

One of the reasons why TRSV may have become able to jump host types is the fact that it is an RNA virus. These pathogens lack a proofreading function that is used inside the genome to correct replication errors. As such, new generations of the virus can have different infective properties.

“The increasing prevalence of TRSV in conjunction with other bee viruses is associated with a gradual decline of host populations and supports the view that viral infections have a significant negative impact on colony survival,” the team concludes in the new research paper.