A critical piece in California’s fight against the deadly citrus disease Huanglongbing (HLB) will soon begin research under tightly controlled biosafety conditions near the University of California, Riverside campus.

The much-anticipated Biosafety Level 3 (BSL3) lab built solely with private money in a public-private partnership will soon commence work to either cure an insidious disease or make its impacts moot for commercial citrus growers concerned that they could lose their livelihoods to a bacterial infection spread by insects that already exist in California.

Four research studies have been approved so far for the facility. California citrus packers who typically fight over market share agreed several years ago in a private meeting to fund the facility. Joel Nelsen, past president of California Citrus Mutual said his office was contacted several years ago by UC Riverside to help promote the idea of a university-led effort for a BSL3 lab to study citrus diseases.

Challenges related to the public effort were eventually deemed daunting and too costly, leading Nelsen to convene a meeting of citrus industry leaders in Exeter, Calif. Three months later Nelsen had $12 million in private donations earmarked for the containment facility.

The BSL3 lab is one of several in the state, but the only one operated by a private foundation whose mission is solely focused on curing HLB.

There are four BSL levels approved for studies, ranging from the lowest (1), to the most restrictive (4). Level 4 labs can study the most toxic and dangerous of pathogens in containment, including Ebola. A level 3 lab can study things like yellow fever, the West Nile Virus and the bacteria responsible for tuberculosis. The University of California has five BSL3 facilities, according to UC Spokesperson Pamela Kan-Rice.

As a level 3 lab, the Riverside facility can study the bacteria responsible for HLB, known as Candidatus Liberibacter asiaticus (CLas). While this capability is available in the UC Davis BSL3 facility, lab capacity and regulatory matters made it difficult to do the kind of work the citrus industry needs, according to Alyssa Houtby, government relations director for California Citrus Mutual.

Private control of the Riverside BSL3 lab means a non-government board will determine research priorities. Still, the U.S. Department of Agriculture must grant permits for studies at the lab and is responsible for regulatory oversight and inspections of the facility.

Initial projects

Four research projects will soon look into things such as tolerance and resistance to the disease; possible bactericide applications that could control the Asian citrus psyllid – the insect responsible for vectoring HLB; therapies designed to kill or suppress the CLas bacterium; and, possible early detection methods that could confirm the disease before existing DNA technology can find it.

Georgios Vidalakis, director of the citrus clonal protection program at UC Riverside, says exciting work is already ongoing to investigate why some citrus trees die from the disease, and some seem little-effected by it.

Researchers are already seeing cloned citrus exhibit various symptoms, or none, meaning that there must be more to the disease than scientists understand, Vidalakis said.

The trouble for California citrus research is that the conditions under which Florida has the disease are not the same. Environmental factors are different, thus the need to study the disease under California conditions. Though California does not yet have a confirmed case of the disease in commercial citrus, the disease has been confirmed in residential trees throughout southern California.

Vidalakis says researchers at UCR are also looking at various proteins in the plant that can suggest evidence of the bacterium. In some cases, these proteins have been discovered in the plant before approved DNA testing can confirm evidence of the disease.

The DNA testing now used by regulators as the only method to declare infection takes time and is said to not be thorough enough. Researchers believe the CLas bacterium can exist in parts of a citrus tree, and not in others. This suggests DNA samples can elicit a false negative if plant materials sampled do not contain enough bacteria when tested.

This is why the protein work holds promise, Vidalakis said.