The subjects of this study belong to the populations used for the HBV seroepidemiology survey in Lipa City, Roxas City, Laguna and Leyte. The actual subpopulations are those who are HBsAg positive and those susceptible to HBV as evidenced by negative serology to the three main antigen/antibody systems of HBV. Blood was extracted from the HBsAg positive approximately one year after their initial positive determination to establish seroconversion to HBsAg negative. The susceptibles were also bled to determine those who will convert to HBsAg positive to establish new infection. Calculations were made on the incidence rate of the carrier state. From the prevalence, seroconversion and incidence rates on estimate of the pool size of potential HBsAg donors were established.Laboratory examinations include HBsAg separation and purification. The three major first year objectives of establishment of laboratory facilities for HBsAg purification, anti HBs production, and the collection of PNRC HBsAg positive plasma were achieved. The first batch of PNRC HBsAg positive plasma yielded 10 mg/liter of HBsAg, while the animal immunization produced 460 mL of high titered anti HBs.A total of 22,040 RPHA tests for HBsAg were produced during the year (1989). The reagents were used by the Philippine National Red Cross (65%), the RITM Hepatitis Research Laboratory (25%), and the UP Liver Study Group (10%). Activity for 1990 concentrated on medium scale production of reagents for screening hepatitis B infection, specifically the manufacture of HBV reagents and the corresponding quality control of these products. A total of 2726 units of HBsAg positive blood were collected by the Research Institute for Tropical Medicine (RITM), Laboratory from the Philippine National Red Cross (PNRC), the Bureau of Research Laboratory (BRL) and the Philippine General Hospital (PGH). Approximately 111.8 mg of purified polyclonal antibody HBsAg was collected by preliminary purification of anti-HBsAg from rabbit sera using affinity column chromatography. Reverse passive hemagglutination (R-PHA) cells reagent production amounted to a total of 81.25 mL for the 8.0% preparation and 30 mL for the 1.0% preparation which can perform 34,000 one-point HBsAg testing. PNRC received R-PHA reagents that cover 19,200 one-point test for screening of HBsAg in donor bloods. The technology for the commercial production of HBsAg reagents has been to Medtest through a memorandum of agreement signed on September 26,1991.
The study aims to control the HBV infection in the country by making available low cost HBV reagents and vaccines.