Biomedical Engineering Reference
In-Depth Information
AIDS-like condition. SIV is a target agent for eradication
in SPF macaque colonies.
SIV viral screening of macaque colonies is performed
using immunoassays. The ideal immunoassay uses whole
virus preparations to ensure that all SIV variants are iden-
tified (
Morton et al., 2008
). It is unlikely that animals will
seroconvert unless they are exposed experimentally, housed
with or exposed to African species, or exposed through
fomites. Therefore, confirmation of indeterminate or posi-
tive immunoassay results should be confirmed using PCR
or Western Blot (
Lairmore et al., 1990; Lerche et al., 1994;
Berry et al., 2011
). PCR should target conserved regions of
the viral sequence in order to identify all possible SIV
variants. In general, the genetic variation increases from
LTR
desirable to screen smaller groups of animals for specific
viruses. Screening tests are available for a host of viruses
including Simian Foamy Virus, rhesus cytomegalovirus,
rhesus lymphocryptovirus, simian virus 40, rhesus rhadi-
novirus, measles, lymphocryptovirus, and varicella virus.
However, the potential risk to colony health and limited
effect on research makes regular screening for these viruses
of limited utility in most settings.
Parasitic Disease Surveillance
Control of parasitic infections within a colony is based on
knowledge of parasite life cycles and dependent on the
species of NHP and housing options available. Screening
for parasites involves a combination of strict quarantine,
rigorous attention to clinical signs of infection (i.e. diar-
rhea), strict pest control measures, and preventive antipar-
asitic treatment when necessary. Animals can be screened
using fecal flotation for a wide variety of parasite ova.
There are also specialized immunoassays to recognize
specific protozoal or parasitic infections.
Eliminating parasites in indoor, singly housed animals
is easier than in outdoor housed or group housed animals.
The approach to interrupting life cycles depends on
whether the cycles are direct or indirect. Indirect life cycles
require intermediate hosts, often small rodents or insects. If
these can be eliminated, the life cycle and further trans-
mission can be interrupted, highlighting the importance of
adequate pest control. Elimination of intermediate hosts is
not always feasible depending on the housing environment.
Direct life cycles do not require a secondary host but their
lifecycle may be broken by a combination of antiparasitic
therapies and rigorous sanitation practices. Animals should
be treated for and cleared of parasites before moving to new
groups or clearing quarantine.
The intensity of a parasite surveillance program will
vary with the species of NHPs, their source, and the
management and housing practices. The choice of anthel-
mintics will be dictated by the agents identified in the
surveillance program.
One specific concern is malarial disease. Animals from
US and European sources should not have been exposed to
this agent as malaria is generally not spread in these
regions. The main concern is with imported animals from
areas where malaria is endemic (
Ameri, 2010
). In these
animals, malaria can cause disease and potentially spread
directly to other animals through blood transfusion,
congenital infection, or percutaneous inoculation. An
additional concern is that these animals could potentially
introduce disease into the USA or Europe given the
proliferation of competent vectors in certain areas as
a consequence of global warming. If treatment is required,
the current CDC recommendations for treatment of malaria
should be followed (
Griffith et al., 2007
).
env. SIV is also included in an
available multiplex microbead immunoassay and this can
be used to screen large numbers of animals for SIV anti-
bodies (
Khan et al., 2006
).
Simian T-lymphotropic virus (STLV) is the fourth virus
included as a target for eradication from specific pathogen
free breeding colonies. Many macaque colonies historically
had high seroprevalence rates but the virus causes
subclinical infection in these animals. In contrast, in
African species, including vervets, gorillas, and baboons
(
Lerche and Osborn, 2003
), the virus may cause lympho-
proliferative disease. Screening for STLV is important
primarily to form and maintain SPF colonies but may also
be beneficial as this agent is a potential confounder of
experimental research (
Lerche and Osborn, 2003
). The
virus shares significant sequence homology with human
T-lymphotropic virus (HTLV) and HTLV specific immu-
noassays can be used to screen for disease (
Meertens et al.,
2001
). PCR or Western Blot can be used to confirm positive
test results.
/
gag
/
pol
/
Simian Hemorrhagic Fever Virus
Simian hemorrhagic fever is an arterivirus that infects
many African species subclinically but can cause serious
and fatal disease in macaques. Strict separation of African
and Asian species is important to limit spread of this
disease within a colony. Screening newly imported African
green monkeys, baboons, or Patas monkeys should be
strongly considered during the quarantine period. Indirect
immunofluorescence assays and ELISA are available for
screening (
Godeny, 2002
).
Additional Viral Screening
The aforementioned viruses form the backbone of a viral
screening program. Additional viral screening should be
performed as needed for research or management needs or
if an expanded-SPF program is desired. The costs of testing
and potential benefits should be carefully weighed before
large scale screening programs are implemented. It may be
