E. coli HCP ELISA Kit

13 September 2022
 Importance: HIGH
E. coli HCP ELISA Kit, 2G, Item # F1020, Now Available  

 
Dear Customer,
 
This letter is to provide all current customers of our E. coli HCP ELISA Kit, catalog # F410 [available since September 2005], with notification of a resupply of the critical components used in this assay. Based on the current supply and demand of this kit, we expect the depletion of the current reagents to occur within the next 9 - 10 months. 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 in order to transition to the new reagents. Kits, Item # F1020, based on the new antibodies are now available, so that you can begin bridging studies.

Cygnus Technologies produced, characterized, and qualified large pools of the new capture and detection antibodies that will replace the current antibody lots. These antibodies have been generated through immunization against a new lot of E. coli host cell protein derived from the mild lysate of DH5α, BL21, JM109, TOP10F, K12, & MC1061 E. coli strains. The immunization was conducted in the same way as was performed in generating the F410 reagents and the antibodies have been affinity purified using the same procedures as the original reagents. The coverage of the new antibodies to the E. coli HCP antigen was determined to be 87-88% by Antibody Affinity Extraction combined with Mass Spectrometry. More importantly, Cygnus Technologies has evaluated these new antibodies in the ELISA using a panel of 5 process samples obtained from several customers. Most of the samples in our test panel did not show a significant difference between antibodies, however some samples showed differences of up to 4-fold between the two assays. There was no trend for consistently higher or lower values in one assay or the other. Such differences are expected and should not be concluded to mean one assay is more sensitive or more broadly reactive. 

The following table compares F410 and F1020 assay design and specifications and highlights changes:
 

We suggest at least the following studies be performed to qualify the F1020 kit and corresponding capture antibody:

1. Establish the mean and acceptable range for your controls with the F1020 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 in-process and drug substance samples using the F410 and F1020 kits in parallel to determine if there is a consistent and significant difference and bias (higher or lower values) from the F410 kit.
    
3. Perform 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 F410 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. Changing the immunoreagents changes the originally validated specificity of the HCP ELISA for each product, regardless of whether the measured ppm levels are the same or not. That requires re-validation of immunoreactivity and updating of the HCP ELISA SOP before the new F1020 kits can be used for lot release testing of DS lots previously approved for testing with F410.

Kits using the new antibody are now available, so that you can begin bridging studies.

Please forward a copy of this notification to those in your organization affected by this change.

Cygnus Technologies strives to provide you with the highest quality products and services, and we hope that this notification will result in as little disruption to your processes as possible. If you have any questions or concerns, please email technical services at techsupport@cygnustechnologies.com and we will be pleased to arrange teleconference to discuss the use of orthogonal testing to better understand any observed differences.