virology
Our virology laboratory consists of a team of scientists and skilful laboratory technicians working together to isolate, identify viruses and produce autogenous vaccines for a wide range of animal viruses. Beside providing diagnostic analysis to veterinarians, our team also has the capability to design specific in vitro assays to help in the development of new products or testing the activity of existing products. For this embryonated egg, multiple primary cells or continuous cell lines (MDCK, Vero, LMH, MA-104, etc) can be used. A large collection of different target viruses (Table 1) is available. Our comprehensive facility has the capability to conduct multiple testing (ex: cell culture, PCR, qPCR, and ELISA) to ensure that all your needs are served under one roof.
Viruses available for testing
Below is a list of viruses (not limited) that is available for in vitro assays.
Table 1. List of viruses. Recent fields and prototype strains
Assay capabilities
Below is the description of some of the assays that we have readily developed in our laboratory.
Cytotoxicity assay
Physical and chemical agents may cause toxicity on cells. In vitro viability and cytotoxicity assay with cultured cells are widely used for cytotoxicity test of chemicals or drug screening. The evaluation is based on the reduction of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) by viable cells to form purple formazan crystal which can be measured spectrophotometrically. Various concentrations of substances can be tested on target cells in 96-well plate format. The 50% Cytotoxicity concentration (CC50) is defined as the substance concentration that reduced the cell viability by 50%. Sample type can be a drug candidate, antiviral substance, toxin, or feed additives.
Antiviral testing
This test evaluates the ability of the substance to inhibit virus replication/production in cell culture. It is performed by infecting cells in the presence of different concentrations of test substance, collecting cells and cell culture supernatants at different timepoints after several cycle of viral replication. Different mode of treatment/delivery of the substance can also be tested here.
50 Percent Tissue Culture Infectious Dose (TCID50) end point dilution
The TCID50 is the amount of virus required to kill 50% of the cells in a well. The assay is performed by inoculating serially diluted cell culture supernatant/virus stock into a permissive cell line and incubating them for several days. The presence of Cytopathic effect (CPE) is examined by visual observation under light microscope. The titre of the virus is calculated using Reed and Muench method or by plaque forming units.
Hemagglutination Inhibition (HI) assay (for influenza, or other hemagglutinating viruses)
The principal of HI is the inhibition of hemagglutination of Influenza by antibodies against the virus. The hemagglutinin protein (HA) of the influenza virus binds to the sialic acid receptor or red blood cells (RBCs). This process is called hemagglutination. When influenza virus binds to RBCs, the influenza virus will hemagglutinate RBCs and causing the formation of a lattice. If a serum containing influenza antibodies is added to the virus before addition of RBCs, the antibodies present in the serum will bind to the virus and inhibit the hemagglutination process. The highest dilution of the serum that inhibit hemagglutination is called HI titre.
Microneutralization or Virus neutralization assay
This test is performed to evaluate the presence of functional antibodies to prevent viral infection. Prediluted antibodies (or serum from vaccinated animals) are pre incubated with target virus/toxin for some length of time then the complex is inoculated into permissive cell line. After several hours(days) of incubation, the presence of CPE is examined under light microscope. If the virus/toxin doesn’t produce cytopathic effect, cell viability is measured by MTT assay.
