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Cygnus is pleased to announce the re-introduction of HEK 293 Host Cell Protein ELISA kit. This 2nd Generation kit utilizes antibodies derived from the same pool of goat anti-HEK antiserum used in the 1st Generation kit, however this antiserum has now been affinity purified with new and a more represenatitve preparation of HCPs typically found in virus, vaccine and recombinant protein products.

Important Subject: Replacement Antibody Pool for the HEK 293 HCP ELISA Kit, Cat # F650

This is to notify all current customers of our Catalog # F650, HEK 293 Host Cell Protein ELISA Kit, of a pending change to the capture and detector antibodies used in this assay. The HEK kit sales have increased dramatically in the last two years necessitating the need for a replacement antibody pool ahead of our previous projections. Based on the current supply and demand for this kit, we expect the depletion of the current antibody to occur within the next nine months. New antibodies have been produced and developed into an ELISA format otherwise identical to the format of the current F650 kit. This notification is done in advance to allow you time to plan and perform any bridging, re-qualification, or re-validation studies that you may deem necessary for transition to the new antibody.

Cygnus has qualified large pools of the new antibody that will replace the current lot of antibody. These new antibodies were produced in both goats and rabbits. The antigen used to generate these antibodies was processed in the same way as the antigen used for the current antibody. Also, the new antibodies were affinity purified by the same procedure using the same HCP preparation as used to affinity purify the current antibody. New kits will use the rabbit antibody as the detector and a blend of both goat and rabbit antibodies for capture. These antibodies show coverage to the majority of the HCPs found in HEK as evidenced by Antibody Affinity Extraction (AAE), a method with far better sensitivity and specificity than 2D Western blot. Moreover, Cygnus Technologies has evaluated these new antibodies in the ELISA using a panel of 20 process samples obtained from several customers. In this study, ten final product samples were tested giving an average HCP concentration of 146 ng/mL by the current assay and 201 ng/mL by the new antibody assay. For the ten in-process samples, the average concentration was 55 µg/mL for the current assay and 52.6 µg/mL for the new antibody assay. While most of the samples in our test panel gave less than a 2-fold difference between antibodies, some samples showed differences of up to 5-fold between the two assays. There was no trend for consistently higher or lower values in one assay or the other. 

We suggest at least the following studies be performed to qualify the new antibody:

1. Establish the mean and acceptable range for your controls with the new kit. These values may be different (higher or lower) relative to the current antibody. To avoid failing runs due to controls ‘out of specification’ it may be necessary to set a new range. If you use other curve parameters such as ODs as an indirect specification, these too may require a new range to be established.

2. Test previous in-process and drug substance samples using the new antibody to determine if there is a consistent and significant difference and bias (higher or lower values) from the kit using the old antibody.

3. We suggest performing dilution linearity and spike recovery on your samples with the new antibodies to assure accuracy and specificity.

4. Orthogonal determination of coverage is best determined using our AAE method. We recommend performing AAE on at least two samples: 1) an upstream harvest sample to determine coverage to the majority of the proteome and 2) a downstream sample to determine coverage those HCPs that persist through the purification process. Cygnus can perform the AAE analysis for you.

5. If you are using the F650 kit for lot release testing, determine what if any effect differences in control and sample values will have on your release criteria and document those changes.

Kits using the new antibody will be available in March 2017, so that you can begin comparison studies. New kits will be distinguished from old kits by the letter 'R' at the end of the catalog number. To order ‘new’ kits, please specify catalog # F650R on the purchase order. If not specified, current/’old’ kits will be shipped until our supplies are exhausted.

If you have any questions or concerns, please feel free to contact our Technical Services Department.


Catalog # Size Price Qty.
F650 1 kit $690.00