Development of a validated molecular analytical method to determine the viral safety of F(AB´)(2) products: A novel application for a well-known technique

The immunotherapy agents derived from horses are biological products that allow the neutralization of clinically relevant immunogens, such as the SARS-CoV-2 virus that causes COVID-19, or the neutralization of toxins present in the venoms of snakes, spiders, and other poisonous animals. Due to their importance, detecting adventitious viruses in equine hyperimmune serum (raw material in industrial processes) is a critical step to support the safety of products for human use, and, in consequence, it is a requirement for commercialization and distribution. The safety of the finished product is based on three complementary approaches: (i) testing of the source material (horse serum) donations, (ii) release of the starting material (i.e., pool of horse serum) based on non-reactivity for a range of human infectious or pathogenic viruses, and (iii) validate (selected) steps of the manufacturing process for their capacity to inactivate and/or remove a wide range of viruses potentially present in the starting material. Orthogonal approaches to reduce viral contamination risk include implementing a reliable and validated system for detecting adventitious viruses. Thus, it is necessary to establish trustworthy and sufficiently sensitive analytical methods to evidence the lack of viruses to assure the safety of the therapeutic product. Therefore, in this research, an analytical method based on end-point Reverse Transcription Polymerase Chain Reaction (RT-PCR) was developed, implemented, and validated in hyperimmune equine serum samples to detect Venezuelan equine encephalitis virus, West Nile virus, and Rabies virus.