Optimal Multiplicity Of Infection Research Articles

A rapid method for estimation of baculovirus titer based on viable cell size

Baculovirus protein expression system is a powerful tool for producing recombinant proteins. To optimize conditions for efficient recombinant protein expression, it is important to determine titer of virus stock for arriving at an optimal multiplicity of infection (MOI) that maximizes recombinant protein expression. Traditionally plaque assays have been used for titer determination. Other methods such as endpoint dilution, quantitative real-time polymerase chain reaction and flow cytometry have been developed to aid the determination of virus titers. However, most of these methods are time-consuming and labor intensive. In this regard, a simple and rapid method for determination of virus titers based on the cytopathic effects that lead to viable cell size increase following virus infection is presented in this paper. In this study, the Vi-CELL (Beckman Coulter) was used to measure cell-diameter over a range of virus dilutions, following infection. Applying statistical modeling techniques, the viable cell-diameter data was used to estimate the virus titer. The results indicated that the viable cell-diameter based titer estimation to be reliable and comparable to titers determined by the traditional plaque assay.

Receptors for Theiler's murine encephalomyelitis virus: characterization by using rabbit antiviral antiserum.

An immunological assay was developed to characterize the binding of Theiler's murine encephalomyelitis virus to BHK-21 cell receptors. After absorption of the virus and formaldehyde fixation, rabbit antibodies and Staphylococcus aureus protein A labeled with 125I formed a specific complex on the surfaces of the cells. The optimal multiplicity of infection in this system was 10 PFU per cell. The virus was internalized at 33 and 37 degrees C, but internalization did not take place at 25 or 4 degrees C. The binding was proportional to the number of cells and was significant within 30 s. Cell surface receptors were still active after fixation, and only intact viruses were bound, as demonstrated by the lack of binding of the purified, isolated virion proteins VP1, VP2, and VP3.