Automation Streamlines Arbovirus Sample Pooling in New Hampshire
By Carol Loring , MS , field applications specialist , INTEGRA Biosciences
Denise Bolton , supervisor of the Arbovirus Testing Laboratory at the New Hampshire Public Health Laboratories , knew changes to the laboratory ’ s mosquito surveillance program for West Nile / Eastern Equine Encephalitis viruses ( WNV / EEE ) were needed .
“ We always strive to make best use of resources by right-sizing our arbovirus surveillance program through evidencebased testing ,” she said . “ We use mosquito ecology data to determine when to start testing mosquitos in the summer , and test sensitivity data allowed us to increase the numbers of mosquitos in each sample batch .” But as summer 2020 approached and the SARS-CoV-2 pandemic showed no signs of slowing down , Bolton knew that more drastic change was needed .
“ We had been thinking about trying out a pooled testing model for arbovirus surveillance prior to the pandemic . When we realized the surging demand for testing supplies , limited availability of polymerase chain reaction ( PCR ) instrumentation and incredible strain on laboratory staff would continue through summer 2020 , we knew it was time to implement pooled testing .”
Moving to Pooled Testing
Bolton researched pooling methods and wrote a procedure . She performed a “ proof of concept ” study by testing combinations of WNV / EEE positive samples in varying concentrations . Her initial studies demonstrated that even very low positive samples would still be detected in a pool of four specimens .
“ Our validation showed really high accuracy and sensitivity . We implemented pooled testing in summer 2020 , but initially , construction of the pools was performed manually .” Bolton soon realized that the additional step of mosquito pool construction complicated the workflow and occupied over an hour of analyst time , requiring high concentration and focus right when the energy level of the mosquito processor may be flagging .
We always strive to make best use of resources by right-sizing our arbovirus surveillance program through evidence-based testing .”
“ Mosquito processing is really labor intensive . There are many steps requiring uncapping and capping of tubes and pipetting of samples , and all must be performed while following strict safety protocols . Adding a manual pooling step at the end of process was quite risky from a quality standpoint . I worried about the opportunity for analyst error in constructing the pools .”
Reducing Opportunity for Error
Bolton decided to automate the pooling of samples on the INTEGRA ASSIST PLUS pipetting robot .
“ I was already familiar with the ASSIST PLUS , as we use it for handling our COVID-19 samples ,” she said . “ It was easy to write a pooling program on the VIALAB software that comes with the instrument , and the flexibility of the INTEGRA pipettes meant there was no need to change our mosquito processing method .”
Bolton uses the INTEGRA VOYAGER eight channel pipette on the robot . This adjustable tip spacing pipette transfers sample from 2ml tubes into a 96-well plate for the pool construction . Bolton added that in the simplified pooling process they developed , a 200 µ l pool is constructed from four samples . After pooling is completed the ASSIST PLUS pipetting robot then adds lysis buffer directly to the sample pools .
Arbovirus Laboratory Supervisor Denise Bolton prepares the INTEGRA ASSIST PLUS pipetting robot for pooling arbovirus specimens . Photo : INTEGRA Biosciences
16 LAB MATTERS Spring 2022