Bull Pan Am Health Orgm 14(3), 1980.
BREEDING OF AOTUS MONKEYS FOR HUMAN MALARIA RESEARCH
Karl H. Rieckmann,’ John E. K. Mrema,‘: Peggy H. Marshall,3 and Diane M. HafnerS
The owl (Aotus) monkey ti an important experimental host for
human malaria, but one currently in short supply. This shortage
of owl monkeys is hampering work to develop effective antimalar-
ial drugs and vaccines. The following article describes the breed-
ing performance of a small colony of Aotus monkeys which, zy
projected on a larger scale, could Partially overcome the problem
presented by the scarcity of these primates.
Introduction
Owl monkeys (Aotus trivilgutus) from
South America have proven useful models for
studying a number of different human dis-
eases (l-6). Aotus trizhgatus grtieimembra,
found predominantly in the northern part of
Colombia (7), is generally regarded as the
best experimental host for falciparum malaria
(8). Because of increasing concern about the
depletion of nonhuman primates from their
habitats, greater emphasis is now being given
to the conservation and management of this
renewable natural resource (9, 10); and in
order to meet biomedical research needs for
these monkeys, controlled extraction of ani-
mals from their natural environment will
undoubtedly have to be supplemented by the
breeding of primates in captivity (II).
This article describes the breeding per-
formance of our small colony of owl monkeys
‘Professor. Division of Tropical and Geographic Med- icine. University of New Mexico School of Medicine, Albuquerque. New Mexico 87131, U.S.A. This work was supported by the Agency for International Develop- ment. contract Nos. AID/ta-C-1259 and AID/DSPE-C- 0036.
2Assistant Professor. Division of Tropical and Geo- graphic Medicine.
3Research Animal Technician, Division of Tropical and Geographic Medicine.
over a period of three and a half years. Male-
female pairs were selected at random, housed
in individual cages, and only separated from
one another because of behavioral incom-
patibility or illness. In view of a suggestion
that the low birth-rates observed among owl
monkeys in captivity might be improved by
mating monkeys of the same karyotype (12,
13), we determined retrospectively whether
the chromosomal pattern of monkey pairs in
our colony had any relationship to their re-
productive performance.
Materials and Methods
A majority of the adult owl monkeys in
our colony are A. t. griseimembru (14, 15),
phenotype B pelage (16), that were captured
originally in Colombia and subsequently
transferred to our primate facility during
1973 and 1974. Most of them were used in
malaria research experiments involving one
or more exposures to sublethal, drug-sup-
pressed infections of Plasmodium falciparum.
During the first two or three years in captivi- ty, the monkeys were kept in groups of three
or four per cage, under environmental con-
ditions and on diets similar to those described
previously (8); they produced only occasional
offspring during this period of time.
252
PAHO BULLETIN l vol.14,
no.
3, 1980
Rieckmann et al. l BREEDING OF AOTUS MONKEYS 2.53
In July 1976, as more cages became avail-
able, four male and four female monkeys
were paired rather arbitrarily on the basis of
behavioral compatibility and each male-
female pair was placed in a separate cage.
During the next 18 months, 12 more pairs
were formed and housed in separate cages
(Table 1). Included in this pairing were two
other A. t. gnlseimembra from Colombia
that had previously been used elsewhere in
eye research and two male Aotus monkeys
from Bolivia that were phenotypically differ-
ent from the Colombian monkeys. Each pair
was monitored carefully for behavioral com-
patibility and, if fighting was noted, the
members of the pair were separated and if
possible reassigned to compatible partners.
Thus, breeding partners from four pairs were
changed during the course of the study. No
attempt was ever made to pair monkeys
according to matching karyotypes. Offspring
shared their parents’ cage until they were
about 1 year old. They were then separated
from their parents and housed with other
compatible monkeys born in captivity.
An effort was made to determine the
Table 1. Offspring produced by Aotus monkeys of different karyotypes between July 1976 and December 1979. -__ P.XYllC.?.l Parental
ND. karyotype 1976 1977 1978 1979 _-
M F M F 7-9" 10-u. l-3 4-6 7-9 10-12 1-3 4-6 7-9 10-12 l-3 4-6 7-9 10-12
-- -- 45 04 14 91 91 12 19 19 96 57 21 44 28 28 90 90 70 47 Hlf 849 831
86 II II
06 III III
42 I" III
48 II III 31 II II
43 III III
94 II II 50 II III 94 II II
54 II II
93 III III
35 I" IV
38 I" IV 07 I" II
31e III 'II H27f III III
92 III III
53 III III
t15f II II
82 "I II
51 "I II
4- Ab A M-11=
+ M-11
+ M-IV
t F-11
4 F-IV
Cd F-II
+ F-II
t
r
t
F-III
M-IV
M-111 F-III
d
f
F-II
M-IV
M-I”
A +
*
F-II + rc
*
c
c M-II
*
M
A M
P M
M-P
F
F
F
F
M M
M F M M M F F M F M M F ” F M F M F M M
aArabic numerals refer to month of the year. bA = abortion.
CM = male offspring; F= female offspring; Roman numerals refer to karyotype class. dArrows indicate start ( + ; or end ( -c ; of pairing.
eMonkey 31 was subsequently paired with monkey 91 (shown towards top of table;.
254
karyotypes of parental pairs and older off-
spring after the colony had experienced over
a dozen live births. About 2 ml of blood was
collected from each monkey, transferred into
heparinized tubes containing 2 ml of Nu-
trient Mixture F10 (GIBCO, Grand Island,
New York) and forwarded to Dr. Nancy Ma,
Pathobiology, Inc., Marlboro, Massachusetts.
After culturing leucocytes from these pe-
ripheral blood specimens (I 7), conventional
metaphase chromosome spreads were treated
for demonstration of G-banding and photo-
graphed for analysis of karyotypes (16). The
identity of the breeding partners and their
offspring was not disclosed to Dr. Ma until she
had forwarded the results to us.
Results
The Aotw monkey colony, consisting of 34
Colombian and two Bolivian monkeys, expe-
rienced 47 live births and four abortions
during a total pairing period of 542 months
(Tables 1 and 2). This represents an average of about one live birth for each year that a pair was housed together. Three of the viable
offspring resulted from matings between
Bolivian and Colombian monkeys.
Table 1 shows that 18 of the 19 female
monkeys experienced at least one live birth
during the 7 to 42 months that different
PAHO BULLETIN . vol. 14, no. 3, 1980
pairs were housed together. Two monkeys
produced one live offspring, eight produced
two, four produced three, and four monkeys
produced four or more live offspring. Births
appeared to be distributed randomly through-
out the year, and the survival rate of live off-
spring was 95.7 per cent. The gestation
period, as determined by the shortest interval
between pairing and parturition or between
two successive parturitions, was less than 146
days in three cases.
Karyotypic analysis of 34 adult A. t. grisei-
mem bra and 16 of their offspring showed that
they belonged to one of three karyotypic (K)
groups: K II (2n= 54), K III (2n = 53), or K
IV (2n= 52). The chromosome pairs of all
three karyotypes have matching elements,
with the exception of the K IV metacentric
pair Al and the K II acrocentric pair B13 and
subtelocentric pair B14 (16). However, these
three unmatched pairs are found as single
chromosomes in K III, indicating hybridiza-
tion between monkeys of karyotypes K II and
K IV. The mating of the two phenotypically
different male monkeys from Bolivia (K VI)
with two female monkeys from Colombia (K
II) resulted in the birth of hybrid monkeys.
The hybrids had 52 chromosomes contain-
ing haploid sets from K VI (2n=49) and K
II (2n = 54).
Table 2 shows that the breeding perfor-
mance among monkey pairs of the same
Table 2. Summary of the breeding experience with various grc~ups of Aotw monkeys between July 1976 and December 1979.
Karyotype of parent
pairs
No. of
pairs Pairing period No. of live
(months; births
No. of
abortions Average pairing
period
(months:
Average no. of
live births during
each 12 months
of pairing
Same karyotyfxs 14 358 30 4 25.6 1.0
K II 6 129 13 2 21.5 1.2
K III 6 189 13 1 31.5 0.8
K IV 2 40 4 1 20.0 1.2
DiJferent karyotyfws 7 184 17 0 26.3 1.1
Rieckmann et al. l BREEDING OF AOTUS MONKEYS
karyotype was similar to that among pairs in
which the two members had different karyo-
types. Birth rates in the three different
karyotypic groups of identically Paired mon-
keys were also comparable to one another.
Discussion
The birth and survival rates of A. t. grisei-
membra in our colony have been considerably
higher than those reported in other Aotw
colonies (12, 13). The breeding performance
of monkey pairs, matched solely according to
behavioral compatibility, is also substantially
greater than that observed in colonies where
pairs were matched according to their karyo-
types (13). In fact, retrospective analysis of
parental karyotypes in our colony revealed
that no advantage would heve been gained by
karyotypic matching of monkey pairs. (It also
confirmed our ability to recognize A. t. grisei-
membra monkeys originating in Colombia by
the appearance of their pelts.) Although ade-
quate housing, acclimatization, nutrition,
and husbandry practices are undoubtedly im-
portant, we feel that personal care and gentle
handling of these monkeys have been primari-
ly responsible for the success achieved in our
breeding colony.
The recent identification of a hybrid
monkey, presumably the offspring of A. t. tri-
vlrgatus from Brazil and A. t. grtieimembra
from Colombia, was the first indication that
phenotypically different Aotus monkeys are
capable of producing viable offspring (18).
The three live births observed in our colony
after mating phenotypically disparate mon-
keys from Bolivia and Colombia indicate that
Aotus monkeys from other areas of South
America can also produce hybrid offspring. It
will be interesting to compare the reproduc-
tive performance of such monkeys with that of
phenotypically similar ones and to observe the
fertility of their hybrid offspring.
Different varieties of Aotus monkeys vary in
their susceptibility to human malaria para-
sites, particularly to P. falci’parum (8, 19).
Golden-throated A. t. tnin’rgatw from the
southern part of Colombia were found not
susceptible to strains of P. falciparum that
were virulent for grayish-pelted A. t. gn’sei-
membra from the northern part of the coun-
try. In our colony, the Aotus monkeys from
Bolivia developed only low-grade infections
after inoculation of parasites of the FVO
strain of P. falciparum; this is in marked con-
trast to the acute fulminating infections
observed in the A. t. griseimembra monkeys.
It will therefore be important to determine
the susceptibility to falciparum malaria of our
hybrid Bolivian-Colombian offspring after
they are old enough to be infected.
Our findings indicate that the successful
breeding of Aotus monkeys in captivity is
possible without resorting to costly chromoso-
ma1 karyotype analysis. Therefore, efforts to
establish large Aotus breeding colonies should
now be intensified in order to provide urgent-
ly needed experimental hosts for biomedical
research. Such colonies are particularly neces-
sary for the evaluation of new antimalarial
drugs and vaccines.
ACKNOWLEDGMENTS
We wish to express our appreciation to Dr. M. Evans for the photograph. Finally, we
S. B. Snyder for his advice and assistance dur- would like to acknowledge the service pro-
ing the initial formation of the colony. We vided by Dr. N. Ma, Pathobiology Inc.,
would also like to thank L. Dunnahoo for her Marlboro, Massachusetts in determining the
256 PAHO BULLETIN . vol. 14, no. 3, 1980
SUMMARY
This report describes the breeding performance of a small colony of 36 owl (A&us) monkeys from South America. The monkeys were paired for seven to 42 months, and there were 47 live births and four abortions. The survival rate among viable off- spring was 95.7 per cent. This represents an aver- age of about one viable offspring for each year that a pair was housed together. Although 44 of the off- spring resulted from the mating of Aotus trzirirga.
tus griseimembra from Colombia, three were hy-
brid offspring of two phenotypically different pairs of Aotw monkeys from Bolivia and Colombia.
Our findings indicate that A t griseimembru
can breed very well in captivity without being matched according to their chromosomal charac- teristics. Considerate and gentle handling of these primates seems to be the most important factor contributing to successful breeding. In order to meet biomedical research needs for such animals, particularly in the development and assessment of potential antimalarial agents, large-scale breeding of Aotus monkeys should be encouraged.
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DR. HERNANDO GROOT RECEIVES THE 1980
ABRAHAM HORWITZ AWARD FOR
INTER-AMERICAN HEALTH
On 30 September 1980 Dr. Hernando Groot, President of the National Academy of Medicine of Colombia and an internationally recognized expert on dengue and yellow fever, received the 1980 Abraham Horwitz Award for Inter-American Health. The award, named after former PAHO Director Abraham Horwitz, is given each year by the Pan American Health and Education Foundation (PAHEF), a collaborating partner of the Pan American Health Organization, for scientific or pedagogic achievement.
The award ceremony was presided over by Dr. Jorge Michelsen, Vice- Minister of Health of Colombia, and by Dr. Hector R. Acuiia, Director of PAHO. Dr. Abel Wolman, President of the Foundation, presented the award; he pointed out that Dr. Groot was chosen from among 19 nominees in 11 countries as an outstanding scientist, teacher, and public health leader in the field of tropical medicine.
Dr. Groot has been Director of the Carlos Finlay Institute, Vice-Rector of Colombia’s Universidad de 10s Andes, Director of the National Institute of Health of Colombia, and a prolific author of scientific works on tropical medicine. Among his other achievements, Dr. Groot discovered the Guama group of arboviruses; his main contributions to health in the Americas, however, have grown out of research and control efforts directed against dengue and yellow fever.
