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Sentinel Screening Program

Mice and rats at JHU are maintained free of a wide range of excluded pathogens that can affect biomedical research.  All colonies are maintained in barrier housing and routinely manipulated in filtered air change stations using high level disinfectants to prevent cross contamination. Mice and rats are continually tested for infections by use of sentinel animals (from the french "sentinelle" meaning watchtower).   The sentinel mice are outbred female mice on Swiss background, free of designated pathogens (SPF), housed 2 per cage, one cage per single-sided rack.  The sentinel rats are SPF female outbred rats, housed 1 or 2 per cage, one cage per single-sided rack.  At each bedding change, soiled bedding from each of the rack cages is added to the sentinel cage, thus exposing the sentinels to diseases carried by colony animals.  One quarter of all the sentinel cages in each room are tested monthly on a rotating schedule so that each sentinel cage is exposed to colony animal bedding for up to 4 months. Serum from only one of the paired sentinels is evaluated: serum from the second animal is frozen and evaluated in the event of a positive test from the first animal. Mesenteric lymph nodes or spleens from sentinel mice are frozen and tested by PCR when serology suggests an infection with a mouse parvovirus.
Mouse sentinels are evaluated for pathogens in the short screen every month, and additionally for pathogens in the complete screen twice a year. Rat sentinels are evaluated for the rat screen every month.
Investigator Housing in Laboratory  Colonies
Mice and rats are either evaluated as for the central housing colonies, or colony samples submitted quarterly for the same pathogen panel as for central housing. Mice in laboratory housing may not return to central housing.
Incoming animals are tested on arrival for ectoparasites by fur pluck of one animal per cage,and for Helicobacter sp. by fecal PCR.  Two SPF female weanling outbred sentinel animals age 3-6 weeks are used for every 7-14 shipment cages. One sentinel is ear punched and placed in a shipment cage, (the 'contact sentinel') the other is placed in its own cage containing soiled bedding from the shipping box (the 'bedding sentinel').   At the first bedding change, the contact sentinel is removed from the shipment cage and placed with the bedding sentinel.  Both sentinels continue to be exposed to soiled bedding  from every shipment cage at each cage change.  After 6 weeks exposure the sentinels are submitted for the complete mouse or rat screen as described above.  The contact sentinel is tested as described above, while backup serum is stored from the bedding sentinel.
Short Mouse Screen:
Ectoparasites (mites) by microscopic evaluation of fur plucks
Endoparasites (pinworms) by cecal and colon float and anal tape test
Gross necropsy followed by histopathology where indicated by gross findings.
Mouse Hepatitis Virus (MHV)
Epidemic Diarrhea of Infant Mice (rotavirus, EDIM)
Theiler's Murine Encephalomyelitis Virus (TMEV, GDVII)
Mouse Parvovirus (MPV1)(MPV2) (VP2)general (NS1)
Minute Virus of Mice (MMV)
Complete Mouse Screen = agents in short screen PLUS:
Mouse Adenovirus I and II (MAD):
Ectromelia (Ectro)
Lymphocytic Choriomeningitis Virus (LCM)
Mycoplasma pulmonis (M. pulmonis)
Pneumonia Virus of Mice (PVM)
Reovirus (Reo)
Sendai Virus (Sendai)
Mouse Cytomegalovirus (MCMV)

Mouse Norovirus (MNV)
Rat Screen
Ectoparasites (mites) by microscopic evaluation of fur plucks
Endoparasites (pinworms) by cecal float and anal tape test
Pneumonia Virus of Mice (PVM)
Cilia Associated Respiratory Bacillus (CARB)
Mycoplasma pulmonis (M. pulmonis)
Reovirus (Reo)
Sendai Virus (Sendai)
Lymphocytic Choriomeningitis Virus (LCM)
Rat Coronavirus/Sialodacryoadenitis Virus (RCV)
Rat Parvoviruses(RPV and RMV)
Kilham Rat Virus,
H-1 Virus


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