Fuel critical immunogenicity tests, functional assays, and preclinical research with reagents from the world’s only large-scale producer of antibody-depleted human complement and baby rabbit complement. From early discovery to regulatory submission, Pel-Freez delivers quality and consistency you can count on.
Key applications we support
Opsonophagocytic assays (OPA/OPKA)
Pel-Freez’s antibody-depleted human serums and high-activity complement from multiple species support functional testing for vaccines that target bacteria, including Group A and Group B Streptococcus.
Bulk volumes and lot-locked supply ensure consistency across studies and sites.
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Serum bactericidal assays (SBA)
Serum bactericidal assays rely on active complement to assess vaccine-induced protection against pathogens such as N. meningitidis, N. gonorrhea, and Shigella spp. Pel-Freez is a leading supplier of bulk complement-preserved human and animal sera, supporting reliable and reproducible measurement of functional antibody responses during vaccine R&D.
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Viral neutralization tests
Pel-Freez provides high-quality human and animal sera for viral neutralization assays, including plaque reduction neutralization tests (PRNT), microneutralization, and pseudovirus-based formats.
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Complement sourcing guide for vaccine R&D
Find the right complement for your assay with our Technical Guide for Sourcing Complement Serum for Vaccine Immunogenicity and Efficacy Testing.
Bulk supply & consistency you can count on
From lot-locked supply to cold chain logistics, we make sure your reagents arrive ready to perform.
It all began with rabbits
Beginning in 1911 as a backyard rabbit farm, Pel-Freez now serves the global research community as the only large-scale producer of U.S.-sourced rabbit tissues and blood products, including baby rabbit complement.
With the largest USDA-inspected rabbit facility in the country, we control every step from sourcing to QC to deliver consistent, quality biological reagents to vaccine developers and labs worldwide.
What researchers say about Pel-Freez
“For over a decade Pel-Freez Biologicals has been a consistent supplier of high-quality reagents and an excellent partner."
“Human complement is an essential reagent for much of our research and product testing. [Pel-Freez] has saved us a considerable amount of time and expense allowing us to focus on experiments instead of preparing reagents.”
Frequently Asked Questions
Can I order products from a single lot? Can I order products from several different lots?
Yes, you can request products that originate from a single lot or from several different lots. We are usually able to accommodate these requests but availability may vary due to maximum lot volumes for certain products. We try to maintain a minimum inventory of ten 5+ liter baby rabbit complement (BRC) lots at all times so that customers have options to select from.
We recommend that you contact us directly with your request on our contact page or by emailing biosales@pel-freez.com.
May I receive a sample of your products? Will you hold a reserve of the product while I complete my testing?
Yes! We understand our products are used in a variety of applications and testing is often required to ensure acceptability. We are happy to provide samples and hold reserves up to 30 days. While we often have multiple inquiries for each lot of our products, we do our best to fulfill all customer requests.
How is Pel-Freez Biologicals’ antibody-depleted complement made?
We have developed a proprietary process for antibody removal based on affinity chromatography. Our method results in low residual antibody (<3% vs. feed serum) while maintaining high complement potency.
Should I use human, rabbit, or guinea pig complement for my application?
The WHO has accepted rabbit complement for use in a variety of vaccine efficacy tests and in most cases is a suitable alternative to human complement. Now that Pel-Freez has developed a large-scale commercial of source antibody depleted human complement; however, we encourage new and existing vaccine development programs to evaluate this product for suitability in their assay systems. Guinea pig complement is also a viable option for highly potent complement function.
