Baculovirus Titer Service

Kempbio determines the infectious titer of baculovirus particles in various types of samples using the standard plaque assay and/or the Virocyt Virus Counter. Plaque assay titers require a week for results to be finalized while titers are available using the Virus Counter in less than 24 hours from the receipt of your sample. By comparing results obtained with these two methods we have developed a numerical factor that converts the virus-particle count obtained with the Virocyt counter to plaque forming units.


For the plaque assay, plates of Sf9 cells are exposed to dilutions of the virus sample and covered with an agarose layer. The plates are incubated for one week at 27ºC and stained with a neutral red dye. The titer of the virus is determined from the mean of two wells at two selected dilutions of virus. The results are presented as pfu/mL HTS.


For the rapid Virocyt Virus Counter method samples are diluted and stained with a combination dye containing fluorescent tags for protein and nucleic acid. The counter detects particles that demonstrate coincident signals from the protein and nucleic acid probes above a certain threshold value. These coincident signals register as a virus particle. In addition to baculovirus this method has been used to successfully determine the titer of various other types of viruses including influenza.

To submit samples for titer analysis simply email us at with the identification of each sample submitted. Please be sure to identify which method you would like for us to use to determine the titer. Samples submitted for plaque assay titer cost $375.00 per sample and results will be ready within 10 days of the receipt of the sample(s). The cost for a sample submitted for titer determination using the Virocyt counter is $140.00 and results are typically reported within 24hours of sample receipt. Purchase orders and credit cards (VISA/Master Card) are accepted for payment. The final results are emailed to the Customer as soon as they are available.


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