RITM and its vaccine production
The Purified Cobra Antivenom (PCAV) section of the Biologicals Manufacturing Division (BMD) has been recently awarded with a PhP1 million research grant for year 2019 through the Department of Health’s (DOH) Advancing Health Through Evidence-Assisted Decisions with Health Policy and Systems Research (AHEAD-HPSR) program at the Annual Research Conference of the Research Institute for Tropical Medicine at The Bellevue Hotel, Alabang on December 12, 2018.
The research entitled “Determination of Titer Yield and Purity of Purified Cobra Antivenom (PCAV) Bulk Concentrate Against Naja philippinensis Produced Using Combined Precipitation Technique in the Purification Process” aims to determine the antibody titer and purity of PCAV bulk concentrate and compare it to the usual antibody recovery and purity of the current production process.
“Right now, we are waiting for the review and approval of the RITM-Institutional Animal Care and Use Committee (IACUC). After that, we’ll be submitting it to RIO, who will then coordinate with the Department of Health to process the grant,” said Precious Montales, Bacteriologist II of the PCAV section, which facilitates the conduct of the research.
Since around 1940s to 1999, PCAV has been the sole producer of antivenom in the Philippines under the Biologicals Production Service (BPS). In 2000, the facility was merged to RITM after the BPS’ closure to give way to land developments by Filinvest Corporation. BMD-PCAV produces 4.8 mL of liquid antivenom in ampoules, capable of neutralizing cobra venom, specifically that of the Northern Philippine Cobra or Naja philippinensis.
The production starts with the creation of Cobra Venom Toxoid (CVT) that is injected to horses to hyperimmunize their blood. The equine plasma is then purified and formulated to become PCAV as final product.
The Ammonium Sulfate Precipitation Technique
Following horse blood collection, staff from the Veterinary Research Department (VRD) transports the blood from the VRD – Experimental Animal Facility Annex (VRD-EAFA) in Los Banos to BMD-PCAV for processing and actual production of antivenom. The collected horse blood initially undergoes complete sedimentation to separate the red blood cells from the plasma. The process of sedimentation takes about three (3) to seven (7) days to complete.
A total of about 10 liters of plasma is expected to be collected per batch of production. The purification process starts with the introduction of the Ammonium Sulfate Precipitation Technique which ensures the removal of unwanted proteins and the precipitation of the IgG antibodies. Dialysis and formulation of plasma are done afterwards.
The final product undergoes quality control tests before and after dispensing and filling into sterile ampoules. It is essential to check if product is pyrogenic or not. Pyrogenic ampoules are excluded from the production batch as these can induce fever on patients when injected.
Finally, the ampoules are delivered to the labeling section for packaging and subsequently stored for distribution to hospitals and health centers in the country.
The Combined Precipitation Technique
Ms. Montales explained that the combined precipitation technique will include both the utilization of caprylic acid and ammonium sulfate to increase the yield of antibody titer of the bulk concentrate. This method is expected to enhance the removal of unwanted proteins to obtain the immunoglobulin of interest, the main component in the production of purified cobra antivenom.
According to the Global Burden of Disease 2016 study by the World Health Organization (WHO), an estimated number of 79,000 deaths were caused by venomous animals. The WHO’s 2018 Global Snakebite Burden Report stated that prevalence of snakebite envenoming is inversely proportional to the level of country income, with the prevalence highest in low- and middle-income countries, and lowest in high-income countries.
Evidently, snakebites cases indicated high incidence in many tropical and subtropical countries.
In 2016 alone, the Storage and Distribution Department (SDD) of BMD reported around 10,800 requests for antivenom ampoules to the PCAV Department. Ms. Montales explained that “with the combined precipitation technique, we hope to be able to save on resources and yield higher titer which means higher number of ampoules produced.”
by Ma. Patricia Lansang, Communication and Engagement Office