Transgenic Core (Marten): This absolutely essential core was established in Year 3 of the present funding period to provide transgenic (TG) and gene deficient (KO) mice to the investigators and to have control over both the breeding of the production mice and the transfer of specific genes onto various genetic backgrounds. Under Dr. Marten's direction it has been an extremely well functioning core and he will continue to direct the core during the next funding period. Mice used in this program are separated into two distinct animal rooms within the Animal Resources Department at USC. Based on biohazard concerns for both our transgenic and knockout colony and the other mouse colonies within the University, all of our experimental groups are housed in isolation. The transgenic core, which comprises the strains listed in Table 1, are housed in an additional separate room. These mice are separated from all other mice within the University. This was done because our colony is large and the TG/KO Core technician changes cages for all KO mice (receiving a substantial discount from $1.85/cage to $1.00/cage). The $1.00/cage charge is identical to the charges for all mice within the University and reflects their supplying sterile cages, food, bedding and water to our technician. It should be noted that we have experienced no cage to cage transmission of MHV in our experimental room, nor have we had an outbreak in the TG KO core. All new TG and KO mice acquired by the program are obtained from 'clean' vendors or investigators, quarantined and sero-surveyed prior to being admitted to the core facility. This core controls the back crossing and production breeding of our transgenic and KO mice. A running tab is kept of the total mice in each production colony by age. The core director meets with the core technician every Monday morning to go over problems, changes in needs, updates on back crossing etc. A list of available mice, starting at 4 weeks of age is circulated to all investigators every week. Mice are all used for JHMV experiments between 6 - 7 weeks of age. This scheme allows time for both adjustments in the number of production mice, prioritizing experiments as well as efficient planning. Once per week, mice are moved from the production room to the separate holding room, which is attached to the experimental room. This room also contains all mice purchased directly from vendors prior to their inclusion in the experimental protocols.
