Normal T-cell turnover in sooty mangabeys harboring active simian immunodeficiency virus infection. (1/33)

Sooty mangabeys naturally infected with simian immunodeficiency virus (SIV) remain healthy though they harbor viral loads comparable to those in rhesus macaques that progress to AIDS. To assess the immunologic basis of disease resistance in mangabeys, we compared the effect of SIV infection on T-cell regeneration in both monkey species. Measurement of the proliferation marker Ki-67 by flow cytometry showed that mangabeys harbored proliferating T cells at a level of 3 to 4% in peripheral blood irrespective of their infection status. In contrast, rhesus macaques demonstrated a naturally high fraction of proliferating T cells (7%) that increased two- to threefold following SIV infection. Ki-67(+) T cells were predominantly CD45RA(-), indicating increased proliferation of memory cells in macaques. Quantitation of an episomal DNA product of T-cell receptor alpha rearrangement (termed alpha1 circle) showed that the concentration of recent thymic emigrants in blood decreased with age over a 2-log unit range in both monkey species, consistent with age-related thymic involution. SIV infection caused a limited decrease of alpha1 circle numbers in mangabeys as well as in macaques. Dilution of alpha1 circles by T-cell proliferation likely contributed to this decrease, since alpha1 circle numbers and Ki-67(+) fractions correlated negatively. These findings are compatible with immune exhaustion mediated by abnormal T-cell proliferation, rather than with early thymic failure, in SIV-infected macaques. Normal T-cell turnover in SIV-infected mangabeys provides an explanation for the long-term maintenance of a functional immune system in these hosts.  (+info)

Catarrhine photopigments are optimized for detecting targets against a foliage background. (2/33)

The colour vision of many primates is trichromatic, whereas that of all other mammals is thought to be dichromatic or monochromatic. Moreover, the triplets of cone pigments in different catarrhines (Old World apes and monkeys) are strikingly similar in their spectral positions. We ask whether the selective advantage of trichromacy lies in an enhanced ability to find edible leaves or fruit. Further, we ask whether any factor in these two search tasks has constrained the particular set of cone spectral sensitivities observed in all catarrhines. We measured the spectral properties of the natural environments of six primate species in Uganda: Pan troglodytes, Cercopithecus mitis, Cercopithecus ascanius, Lophocebus albigena, Colobus guereza and Colobus badius. We concentrated on the fruit and leaves in their diets and the leaves of the trees that make up the background against which these diet items must be found. We plotted these measured stimuli in colour spaces appropriate for each primate species, and found that both frugivory and folivory are facilitated by the extra dimension of colour vision found in catarrhines but lacking in most other mammals. Furthermore, by treating the task of searching for food as a signal-detection task, we show that, of all possible combinations of cone sensitivities, the spectral positions of the actual primate pigments are optimal for finding fruit or young leaves against the background of mature leaves. This is because the variance of the chromaticities of the mature leaves is minimised in one channel of the primate's colour vision, so allowing anything that is not a mature leaf to stand out.  (+info)

Characterization of novel simian immunodeficiency viruses from red-capped mangabeys from Nigeria (SIVrcmNG409 and -NG411). (3/33)

Two novel simian immunodeficiency virus (SIV) strains from wild-caught red-capped mangabeys (Cercocebus torquatus torquatus) from Nigeria were characterized. Sequence analysis of the fully sequenced SIV strain rcmNG411 (SIVrcmNG411) and gag and pol sequence of SIVrcmNG409 revealed that they were genetically most closely related to the recently characterized SIVrcm from Gabon (SIVrcmGB1). Thus, red-capped mangabeys from distant geographic locations harbor a common lineage of SIV. SIVrcmNG411 carried a vpx gene in addition to vpr, suggesting a common evolutionary ancestor with SIVsm (from sooty mangabeys). However, SIVrcm was only marginally closer to SIVsm in that region than to any of the other lentiviruses. SIVrcm showed the highest similarity in pol with SIVdrl, isolated from a drill, a primate that is phylogenetically distinct from mangabey monkeys, and clustered with other primate lentiviruses (primarily SIVcpz [from chimpanzees] and SIVagmSab [from African green monkeys]) discordantly in different regions of the genome, suggesting a history of recombination. Despite the genetic relationship to SIVcpz in the pol gene, SIVrcmNG411 did not replicate in chimpanzee peripheral blood mononuclear cells (PBMC), although two other viruses unrelated to SIVcpz, SIVmndGB1 (from mandrills) and SIVlhoest (from L'Hoest monkeys), were able to grow in chimpanzee PBMC. The CCR5 24-bp deletion previously described in red-capped mangabeys from Gabon was also observed in Nigerian red-capped mangabeys, and SIVrcmNG411, like SIVrcmGB1, used CCR2B and STRL33 as coreceptors for virus entry. SIVrcm, SIVsm, SIVmndGB1, and all four SIVlhoest isolates but not SIVsun (from sun-tailed monkeys) replicated efficiently in human PBMC, suggesting that the ability to infect the human host can vary within one lineage.  (+info)

Molecular epidemiology of simian T-lymphotropic virus (STLV) in wild-caught monkeys and apes from Cameroon: a new STLV-1, related to human T-lymphotropic virus subtype F, in a Cercocebus agilis. (4/33)

A serological survey for human T-lymphotropic virus (HTLV)/simian T-lymphotropic virus (STLV) antibodies was performed in 102 wild-caught monkeys and apes from 15 (sub)species originating from Cameroon. Two animals (a Mandrillus sphinx and a Cercocebus agilis) exhibited a complete HTLV-1 seroreactivity pattern while two others lacked either the p24 (a Mandrillus sphinx) or the MTA-1/gp46 bands (a Pan troglodytes). Sequence comparison and phylogenetic analyses, using a 522 bp env gene fragment and the complete LTR, indicated that the two mandrill STLV strains belonged to the HTLV/STLV subtype D clade while the chimpanzee strain clustered in the HTLV/STLV subtype B clade. The Cercocebus agilis STLV strain, the first one found in this species, was closely related to the two HTLV/STLV subtype F strains. Such data indicate that the African biodiversity of STLV-1 in the wild is far from being known and reinforces the hypothesis of interspecies transmission of STLV-1 from monkeys and apes to humans leading to the present day distribution of HTLV-1 in African inhabitants.  (+info)

Complete sequence of a novel highly divergent simian T-cell lymphotropic virus from wild-caught red-capped mangabeys (Cercocebus torquatus) from Cameroon: a new primate T-lymphotropic virus type 3 subtype. (5/33)

Among 65 samples obtained from a primate rescue center located in Cameroon, two female adult red-capped mangabeys (Cercocebus torquatus) (CTO-602 and CTO-604), of wild-caught origin, had a peculiar human T-cell lymphotropic virus type 2 (HTLV-2)-like Western blot seroreactivity (p24, RGD21, +/-K55). Analyses of the simian T-cell lymphotropic virus type 3 (STLV-3)/CTO-604 complete proviral sequence (8,919 bp) indicated that this novel strain was highly divergent from HTLV-1 (60% nucleotide similarity), HTLV-2 (62%), or STLV-2 (62%) prototypes. It was, however, related to STLV-3/PH-969 (87%), a divergent STLV strain previously isolated from an Eritrean baboon. The STLV-3/CTO-604 sequence possesses the major open reading frames corresponding to the structural, enzymatic, and regulatory proteins. However, its long terminal repeat is shorter, with only two 21-bp repeats. Furthermore, as demonstrated by reverse transcriptase PCR, this new STLV exhibits significant differences from STLV-3/PH-969 at the mRNA splice junction position level. In all phylogenetic analyses, STLV-3/CTO-604 and STLV-3/PH-969 clustered in a highly supported single clade, indicating an evolutionary lineage independent from primate T-lymphotropic virus type 1 (PTLV-1) and PTLV-2. Nevertheless, the nucleotide divergence between STLV-3/PH-969 and STLV-3/CTO-604 is equivalent to or higher than the divergence observed between the different HTLV-1 or HTLV-2 subtypes. Thus, the STLV-3/CTO-604 strain can be considered the prototype of a second subtype in the PTLV-3 type. The presence of two related viruses in evolutionarily distantly related African monkeys species, living in two opposite ecosystems (rain forest versus desert), reinforces the possible African origin of PTLV and opens new avenues regarding the search for a possible human counterpart of these viruses in individuals exhibiting such HTLV-2-like seroreactivities.  (+info)

Divergent simian T-cell lymphotropic virus type 3 (STLV-3) in wild-caught Papio hamadryas papio from Senegal: widespread distribution of STLV-3 in Africa. (6/33)

Among eight samples obtained from a French primatology research center, six adult guinea baboons (Papio hamadryas papio), caught in the wild in Senegal, had a peculiar human T-cell leukemia virus type 2 (HTLV-2)-like Western blot seroreactivity (p24(+), GD21(+), K55(+/-)). Partial sequence analyses of the tax genes (433 bp) indicated that these baboons were infected by a novel divergent simian T-cell lymphotropic virus (STLV). Analyses of the complete proviral sequence (8,892 bp) for one of these strains (STLV-3/PPA-F3) indicate that this STLV was highly divergent from the HTLV-1 (61.6% of nucleotide similarity), HTLV-2 (61.2%), or STLV-2 (60.6%) prototype. It was, however, much more closely related to the few other known STLV-3 strains, exhibiting 87 and 89% of nucleotide similarity with STLV-3/PHA-PH969 (formerly PTLV-L/PH969) and STLV-3/CTO-604, respectively. The STLV-3/PPA-F3 sequence possesses the major HTLV or STLV open reading frames corresponding to the structural, enzymatic, and regulatory proteins. However, its long terminal repeat comprises only two 21-bp repeats. In all phylogenetic analyses, STLV-3/PPA-F3 clustered together in a highly supported single clade with the other known strains of STLV-3, indicating an independent evolution from primate T-cell lymphotropic virus type 1 (PTLV-1) and PTLV-2. The finding of a new strain of STLV-3 in a West African monkey (Guinea baboon) greatly enlarges the geographical distribution and the host range of species infected by this PTLV type in the African continent. The recent discovery of several different STLV-3 strains in many different African monkey species, often in contact with humans, strongly suggests potential interspecies transmission events, as it was described for STLV-1, between nonhuman primates but also to humans.  (+info)

A novel, divergent simian T-cell lymphotropic virus type 3 in a wild-caught red-capped mangabey (Cercocebus torquatus torquatus) from Nigeria. (7/33)

We present here a novel, distinct simian T-cell lymphotropic virus (STLV) found in a red-capped mangabey (Cercocebus torquatus) (CTO-NG409), wild-caught in Nigeria, that showed an HTLV-2-like Western blot (WB) seroreactivity. The complete genome (8920 bp) of CTO-NG409 STLV was related to but different from STLV-3/PHA-PH969 (13.5 %) and STLV-3/PPA-F3 (7.6 %), and STLV-3/CTO604 (11.3 %), found in Eritrean and Senegalese baboons, and red-capped mangabeys from Cameroon, respectively. Phylogenetic analysis of a conserved tax (180 bp) sequence and the env gene (1482 bp) confirmed the relatedness of STLV-3/CTO-NG409 to the STLV-3 subgroup. Molecular clock analysis of env estimated that STLV-3/CTO-NG409 diverged from East and West/Central African STLV-3s about 140,900+/-12,400 years ago, suggesting an ancient African origin of STLV-3. Since phylogenetic evidence suggests multiple interspecies transmissions of STLV-1 to humans, and given the antiquity and wide distribution of STLV-3 in Africa, a search for STLV-3 in human African populations with HTLV-2-like WB patterns is warranted.  (+info)

Simian T-cell leukemia virus (STLV) infection in wild primate populations in Cameroon: evidence for dual STLV type 1 and type 3 infection in agile mangabeys (Cercocebus agilis). (8/33)

Three types of human T-cell leukemia virus (HTLV)-simian T-cell leukemia virus (STLV) (collectively called primate T-cell leukemia viruses [PTLVs]) have been characterized, with evidence for zoonotic origin from primates for HTLV type 1 (HTLV-1) and HTLV-2 in Africa. To assess human exposure to STLVs in western Central Africa, we screened for STLV infection in primates hunted in the rain forests of Cameroon. Blood was obtained from 524 animals representing 18 different species. All the animals were wild caught between 1999 and 2002; 328 animals were sampled as bush meat and 196 were pets. Overall, 59 (11.2%) of the primates had antibodies cross-reacting with HTLV-1 and/or HTLV-2 antigens; HTLV-1 infection was confirmed in 37 animals, HTLV-2 infection was confirmed in 9, dual HTLV-1 and HTLV-2 infection was confirmed in 10, and results for 3 animals were indeterminate. Prevalences of infection were significantly lower in pets than in bush meat, 1.5 versus 17.0%, respectively. Discriminatory PCRs identified STLV-1, STLV-3, and STLV-1 and STLV-3 in HTLV-1-, HTLV-2-, and HTLV-1- and HTLV-2-cross-reactive samples, respectively. We identified for the first time STLV-1 sequences in mustached monkeys (Cercopithecus cephus), talapoins (Miopithecus ogouensis), and gorillas (Gorilla gorilla) and confirmed STLV-1 infection in mandrills, African green monkeys, agile mangabeys, and crested mona and greater spot-nosed monkeys. STLV-1 long terminal repeat (LTR) and env sequences revealed that the strains belonged to different PTLV-1 subtypes. A high prevalence of PTLV infection was observed among agile mangabeys (Cercocebus agilis); 89% of bush meat was infected with STLV. Cocirculation of STLV-1 and STLV-3 and STLV-1-STLV-3 coinfections were identified among the agile mangabeys. Phylogenetic analyses of partial LTR sequences indicated that the agile mangabey STLV-3 strains were more related to the STLV-3 CTO604 strain isolated from a red-capped mangabey (Cercocebus torquatus) from Cameroon than to the STLV-3 PH969 strain from an Eritrean baboon or the PPA-F3 strain from a baboon in Senegal. Our study documents for the first time that (i) a substantial proportion of wild-living monkeys in Cameroon is STLV infected, (ii) STLV-1 and STLV-3 cocirculate in the same primate species, (iii) coinfection with STLV-1 and STLV-3 occurs in agile mangabeys, and (iv) humans are exposed to different STLV-1 and STLV-3 subtypes through handling primates as bush meat.  (+info)

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