Amylase iso-enzymes in primates of the families Lemuridae,Cebidae, Cercopithecidae,Hylobatidae and Pongidae

This paper presents the first data in the alpha-amylase isoenzymes in primates of the families: Lemuridae, Cebidae, Cercopithecidae, Hylobatidae and Pongidae. By means of agar-gel electrophoresis of urine samples from 33 individuals belonging to ten species of the above mentioned families a total of 14 different variants of amylase heterogeneity were found.     

Intestinal parasitism—protozoa and helminths—in primates at the Barcelona Zoo

Abstract: The faunistic results regarding intestinal parasitism by protozoa and helminths in 21 primate species (three Cebidae, thirteen Cercopithecidae, one Hylobatidae, one Lemuridae, three Pongidae) are reported. The primate species were housed in four separate galleries. Six faecal samples of each host species were subjected to coprological analysis. Fifteen parasite species were detected: 11 protozoa (Entamoeba coli, E. chattoni, E. hartmanni, Iodamoeba bütschlii, Endolimax nana, Giardia intestinalis, Chilomastix mesnilii, Enteromonas hominis, Trichomonas intestinalis, Balantidium coli, and Blastocystis hominis) and 4 helminths (Ancylostoma sp., Strongyloides fuelleborni, Strongyloides sp., and Trichuris trichiura). The results reveal certain parasitic similarities between host species housed in the same gallery; however, these primate species do not always carry identical parasite species.     

Use of inhibitors to evaluate coreceptor usage by simian and simian/human immunodeficiency viruses and human immunodeficiency virus type 2 in primary cells

We have used coreceptor-targeted inhibitors to investigate which coreceptors are used by human immunodeficiency virus type 1 (HIV-1), simian immunodeficiency viruses (SIV), and human immunodeficiency virus type 2 (HIV-2) to enter peripheral blood mononuclear cells (PBMC). The inhibitors are TAK-779, which is specific for CCR5 and CCR2, aminooxypentane-RANTES, which blocks entry via CCR5 and CCR3, and AMD3100, which targets CXCR4. We found that for all the HIV-1 isolates and all but one of the HIV-2 isolates tested, the only relevant coreceptors were CCR5 and CXCR4. However, one HIV-2 isolate replicated in human PBMC even in the presence of TAK-779 and AMD3100, suggesting that it might use an undefined, alternative coreceptor that is expressed in the cells of some individuals. SIV(mac)239 and SIV(mac)251 (from macaques) were also able to use an alternative coreceptor to enter PBMC from some, but not all, human and macaque donors. The replication in human PBMC of SIV(rcm) (from a red-capped mangabey), a virus which uses CCR2 but not CCR5 for entry, was blocked by TAK-779, suggesting that CCR2 is indeed the paramount coreceptor for this virus in primary cells.     

Envelope glycoproteins from human immunodeficiency virus types 1 and 2 and simian immunodeficiency virus can use human CCR5 as a coreceptor for viral entry and make direct CD4-dependent interactions with this chemokine receptor.

Several members of the chemokine receptor family have recently been identified as coreceptors, with CD4, for entry of human immunodeficiency virus type 1 (HIV-1) into target cells. In this report, we show that the envelope glycoproteins of several strains of HIV-2 and simian immunodeficiency virus (SIV) employ the same chemokine receptors for infection. Envelope glycoproteins from HIV-2 use CCR5 or CXCR4, while those from several strains of SIV use CCR5. Our data indicate also that some viral envelopes can use more than one coreceptor for entry and suggest that some of these coreceptors remain to be identified. To further understand how different envelope molecules use CCR5 as an entry cofactor, we show that soluble purified envelope glycoproteins (SU component) from CCR5-tropic HIV-1, HIV-2, and SIV can compete for binding of iodinated chemokine to CCR5. The competition is dependent on binding of the SU glycoprotein to cell surface CD4 and implies a direct interaction between envelope glycoproteins and CCR5. This interaction is specific since it is not observed with SU glycoprotein from a CXCR4-tropic virus or with a chemokine receptor that is not competent for viral entry (CCR1). For HIV-1, the interaction can be inhibited by antibodies specific for the V3 loop of SU. Soluble CD4 was found to potentiate binding of the HIV-2 ST and SIVmac239 envelope glycoproteins to CCR5, suggesting that a CD4-induced conformational change in SU is required for subsequent binding to CCR5. These data suggest a common fundamental mechanism by which structurally diverse HIV-1, HIV-2, and SIV envelope glycoproteins interact with CD4 and CCR5 to mediate viral entry.     

Tyrosine sulfation of the amino terminus of CCR5 facilitates HIV-1 entry

Chemokine receptors and related seven-transmembrane-segment (7TMS) receptors serve as coreceptors for entry of human and simian immunodeficiency viruses (HIV-1, HIV-2, and SIV) into target cells. Each of these otherwise diverse coreceptors contains an N-terminal region that is acidic and tyrosine rich. Here, we show that the chemokine receptor CCR5, a principal HIV-1 coreceptor, is posttranslationally modified by O-linked glycosylation and by sulfation of its N-terminal tyrosines. Sulfated tyrosines contribute to the binding of CCR5 to MIP-1 alpha, MIP-1 beta, and HIV-1 gp120/CD4 complexes and to the ability of HIV-1 to enter cells expressing CCR5 and CD4. CXCR4, another important HIV-1 coreceptor, is also sulfated. Tyrosine sulfation may contribute to the natural function of many 7TMS receptors and may be a modification common to primate immunodeficiency virus coreceptors.     

The level of CD4 expression limits infection of primary rhesus monkey macrophages by a T-tropic simian immunodeficiency virus and macrophagetropic human immunodeficiency viruses

The entry of primate immunodeficiency viruses into cells is dependent on the interaction of the viral envelope glycoproteins with receptors, CD4, and specific members of the chemokine receptor family. Although in many cases the tropism of these viruses is explained by the qualitative pattern of coreceptor expression, several instances have been observed where the expression of a coreceptor on the cell surface is not sufficient to allow infection by a virus that successfully utilizes the coreceptor in a different context. For example, both the T-tropic simian immunodeficiency virus (SIV) SIVmac239 and the macrophagetropic (M-tropic) SIVmac316 can utilize CD4 and CCR5 as coreceptors, and both viruses can infect primary T lymphocytes, yet only SIVmac316 can efficiently infect CCR5-expressing primary macrophages from rhesus monkeys. Likewise, M-tropic strains of human immunodeficiency virus type 1 (HIV-1) do not infect primary rhesus monkey macrophages efficiently. Here we show that the basis of this restriction is the low level of CD4 on the surface of these cells. Overexpression of human or rhesus monkey CD4 in primary rhesus monkey macrophages allowed infection by both T-tropic and M-tropic SIV and by primary M-tropic HIV-1. By contrast, CCR5 overexpression did not specifically compensate for the inefficient infection of primary monkey macrophages by T-tropic SIV or M-tropic HIV-1. Apparently, the limited ability of these viruses to utilize a low density of CD4 for target cell entry accounts for the restriction of these viruses in primary rhesus monkey macrophages.     

A Broad Range of Chemokine Receptors Are Used by Primary Isolates of Human Immunodeficiency Virus Type 2 as Coreceptors with CD4

Like human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV), HIV-2 requires a coreceptor in addition to CD4 for entry into cells. HIV and SIV coreceptor molecules belong to a family of seven-transmembrane-domain G-protein-coupled receptors. Here we show that primary HIV-2 isolates can use a broad range of coreceptor molecules, including CCR1, CCR2b, CCR3, CCR4, CCR5, and CXCR4. Despite broad coreceptor use, the chemokine ligand SDF-1 substantially blocked HIV-2 infectivity of peripheral blood mononuclear cells, indicating that its receptor, CXCR4, was the predominant coreceptor for infection of these cells. However, expression of CXCR4 together with CD4 on some cell types did not confer susceptibility to infection by all CXCR4-using virus isolates. These data therefore indicate that another factor(s) influences the ability of HIV-2 to replicate in human cell types that express the appropriate receptors for virus entry.     

Simian immunodeficiency viruses of diverse origin can use CXCR4 as a coreceptor for entry into human cells

Primary simian immunodeficiency virus (SIV) isolated from sooty mangabey (SIVsm [n = 6]), stumptail (SIVstm [n = 1]), mandrill (SIVmnd [n = 1]), and African green (SIVagm [n = 1]) primates were examined for their ability to infect human cells and for their coreceptor requirements. All isolates infected human peripheral blood mononuclear cells (PBMCs) from a CCR5(+/+) donor, and seven of eight isolates tested also infected CCR5(-/-) PBMCs. Analysis of coreceptor utilization using GHOST and U87 cell lines revealed that all of the isolates tested used CCR5 and the orphan receptors STRL33 and GPR15. Coreceptors such as CCR2b, CCR3, CCR8, and CX3CR1 were also utilized by some primary SIV isolates. More importantly, we found that CXCR4 was used as a coreceptor by the SIVstm, the SIVagm, and four of the SIVsm isolates in GHOST and U87 cells. These data suggest that primary SIV isolates from diverse primate species can utilize CXCR4 for viral entry, similar to what has been described for human immunodeficiency viruses.     

Evolution of the Sweetness Receptor in Primates. II. Gustatory Responses of Non-human Primates to Nine Compounds Known to be Sweet in Man

The gustatory responses of nine compounds, namely glycine, D-phenylalanine,D-tryptophan, cyanosuosan, magapame, sucrononate, campame, cyclamateand superaspartame, all known as sweet in man, were studiedin 41 species or subspecies of non-human primates, selectedamong Prosimii (Lemuridae and Lorisidae), Platyrrhini (Callitrichidaeand Cebidae) and Catarrhini (Cercopithecidae, Hylobatidae andPongidae). The first six compounds are generally sweet to allprimates, which implies that they interact with the primatesweetness receptors essentially through constant recognitionsites. Campame is sweet only to Cebidae and Catarrhini, cyclamateonly to Catarrhini, superaspartame principally to Callitrichidaeand Catarrhini, which implies that all these compounds interactwith the receptors partly through variable recognition sites.From the present work, from other previous results (where notablyit was observed that alitame is sweet to all primates, ampameonly to Prosimii and Catarrhini, and aspartame only to Catarrhini),and from the multipoint attachment (MPA) theory of sweetnessreception (as elaborated by Nofre and Tinti from a detailedstudy of structure-activity relationships of various sweetenersin man), it is inferred that the primate sweetness receptorsare very likely made up of eight recognition sites, of whichthe first, second, third, fourth, seventh and eighth are constant,and the fifth and sixth variable. From these results and fromthe MPA theory, it is also inferred that the recognition sitesof the primate sweetness receptors could be: Asp-1 or Glu-1,Lys-2, Asp-3 or Glu-3, Thr-4, X-5, X-6, Thr-7, Ser-8, wherethe variable recognition sites X-5 and X-6 would be: Ala-5 andAla-6 for Callitrichidae, Ser-5 and Ala-6 for Cebidae, Ala-5and Thr-6 for Prosimii, and Thr-5 and Thr-6 for Catarrhini.By using Tupaiidae (tree shrews) as a reference outgroup andby means of other structural and functional molecular considerations,it appears that Callitrichidae have retained the most primitivereceptor among the four types of primate receptors. The possibletaxonomic and phylogenetic implications of these findings arediscussed. Chem. Senses 21: 747–762, 1996.     

Simian immunodeficiency virus variants with differential T-cell and macrophage tropism use CCR5 and an unidentified cofactor expressed in CEMx174 cells for efficient entry.

The recent identification of coreceptors that mediate efficient entry of human immunodeficiency virus type 1 (HIV-1) suggests new therapeutic and preventive strategies. We analyzed simian immunodeficiency virus (SIV) entry cofactors to investigate whether the macaque SIV model can be used as an experimental model to evaluate these strategies. Similar to primary HIV-1 isolates, a well-characterized molecular clone, SIVmac239, which replicates poorly but efficiently enters into rhesus alveolar macrophages and an envelope variant, SIVmac239/316Env, with an approximately 1,000-fold-higher replicative capacity in macrophages used the beta-chemokine receptor CCR5 for efficient entry. The transmembrane portion of 316Env allowed low-level entry into cells expressing CCR1, CCR2B, and CCR3. A single amino acid substitution in the V3 loop of SIVmac239/316Env, 321P-->S, impaired the ability to enter into the T-B hybrid cell line CEMx174 but had relatively little effect on entry into primary cells and HOS.CD4 cells expressing CCR5. Although CEMx174 cells do not express CCR5, most SIVmac variants entered this hybrid cell line efficiently but did not enter the parental T-cell line CEM. It seems likely that CEMx174 cells express an as-yet-unidentified, perhaps B-cell-derived cofactor which allows efficient entry of SIVmac.     

CD4-independent, CCR5-dependent simian immunodeficiency virus infection and chemotaxis of human cells

Most simian immunodeficiency virus (SIV), human immunodeficiency virus type 2 (HIV-2), and HIV-1 infection of host peripheral blood mononuclear cells (PBMCs) is CD4 dependent. In some cases, X4 HIV-1 chemotaxis is CD4 independent, and cross-species transmission might be facilitated by CD4-independent entry, which has been demonstrated for some SIV strains in CD4(-) non-T cells. As expected for CCR5-dependent virus, SIV required CD4 on rhesus and pigtail macaque PBMCs for infection and chemotaxis. However, SIV induced the chemotaxis of human PBMCs in a CD4-independent manner. Furthermore, in contrast to the results of studies using transfected human cell lines, SIV did not require CD4 binding to productively infect primary human PBMCs. CD4-independent lymphocyte and macrophage infection may facilitate cross-species transmission, while reacquisition of CD4 dependence may confer a selective advantage for the virus within new host species.     

Utilization of chemokine receptors, orphan receptors, and herpesvirus-encoded receptors by diverse human and simian immunodeficiency viruses.

Human immunodeficiency virus type 1 (HIV-1) requires both CD4 and a coreceptor to infect cells. Macrophage-tropic (M-tropic) HIV-1 strains utilize the chemokine receptor CCR5 in conjunction with CD4 to infect cells, while T-cell-tropic (T-tropic) strains generally utilize CXCR4 as a coreceptor. Some viruses can use both CCR5 and CXCR4 for virus entry (i.e., are dual-tropic), while other chemokine receptors can be used by a subset of virus strains. Due to the genetic diversity of HIV-1, HIV-2, and simian immunodeficiency virus (SIV) and the potential for chemokine receptors other than CCR5 or CXCR4 to influence viral pathogenesis, we tested a panel of 28 HIV-1, HIV-2, and SIV envelope (Env) proteins for the ability to utilize chemokine receptors, orphan receptors, and herpesvirus-encoded chemokine receptor homologs by membrane fusion and virus infection assays. While all Env proteins used either CCR5 or CXCR4 or both, several also used CCR3. Use of CCR3 was strongly dependent on its surface expression levels, with a larger number of viral Env proteins being able to utilize this coreceptor at the higher levels of surface expression. ChemR1, an orphan receptor recently shown to bind the CC chemokine I309 (and therefore renamed CCR8), was expressed in monocyte and lymphocyte cell populations and functioned as a coreceptor for diverse HIV-1, HIV-2, and SIV Env proteins. Use of ChemR1/CCR8 by SIV strains was dependent in part on V3 loop sequences. The orphan receptor V28 supported Env-mediated cell-cell fusion by four T- or dual-tropic HIV-1 and HIV-2 strains. Three additional orphan receptors failed to function for any of the 28 Env proteins tested. Likewise, five of six seven-transmembrane-domain receptors encoded by herpesviruses did not support Env-mediated membrane fusion. However, the chemokine receptor US28, encoded by cytomegalovirus, did support inefficient infection by two HIV-1 strains. These findings indicate that additional chemokine receptors can function as HIV and SIV coreceptors and that surface expression levels can strongly influence coreceptor use.     

Comparative morphology of primate spermatozoa using scanning electron microscopy. I. Families Hominidae,Pongidae, Cercopithecidae and Cebidae

Spermatozoa from 16 species of primates, representing Families Cercopithecidae Cebidae, Pongidae, and Hominidae, were viewed using scanning electron microscopy (SEM). Various techniques of specimen preparation were employed, especially critical point drying using CO₂, but also critical point drying using N₂O as well as air drying using amyl acetate. Details of ultrastructure and identifying features of the various families are presented, with both relationships and differences being evident. Accompanying light micrographs of several of the species illustrate size relationships of the head, midpiece, and principal piece of the tail. Dimensions of these parts of spermatozoa were calculated from such photographs, and add to the interpretation of overall morphology. SEM is of considerable value in understanding many details of structure in spermatozoa, and should contribute to the study of taxonomic affinities among the various primate groups.     

CD4-independent infection of two CD4(-)/CCR5(-)/CXCR4(+) pre-T-cell lines by human and simian immunodeficiency viruses

The infection of CD4-negative cells by variants of tissue culture-adapted human immunodeficiency virus type 1 (HIV-1) or HIV-2 strains has been shown to be mediated by the CXCR4 coreceptor. Here we show that two in vitro-established CD4(-)/CCR5(-)/CXCR4(+) human pre-T-cell lines (A3 and A5) can be productively infected by wild-type laboratory-adapted T-cell-tropic HIV-1 and HIV-2 strains in a CD4-independent, CXCR4-dependent fashion. Despite the absence of CCR5 expression, A3 and A5 cells were susceptible to infection by the simian immunodeficiency viruses SIVmac239 and SIVmac316. Thus, at least in A3 and A5 cells, one or more of the chemokine receptors can efficiently support the entry of HIV and SIV isolates in the absence of CD4. These findings suggest that to infect cells of different compartments, HIV and SIV could have evolved in vivo to bypass CD4 and to interact directly with an alternative receptor.     

Conservation and host specificity of Vpr-mediated cell cycle arrest suggest a fundamental role in primate lentivirus evolution and biology.

The human immunodeficiency virus type 1 (HIV-1) Vpr protein prevents infected cells from passing through mitosis by arresting them in the G2 phase of the cell cycle. Vpr is conserved among all primate lentiviruses, suggesting an important role in the virus life cycle. Moreover, in this study we show that the ability to cause cell cycle arrest is also conserved in Vpr proteins from a wide variety of both tissue culture-passaged and uncultured human (HIV-1 and HIV-2), sooty mangabey (simian immunodeficiency virus SIV(SM)), African green monkey (SIV(AGM)), and Sykes' monkey (SIV(SYK)) isolates. However, this property is cell type specific and appears to depend on the particular primate species from which the cells are derived. SIV(AGM) and SIV(SYK) Vpr proteins are capable of arresting African green monkey cells but are completely inactive in human cells. By contrast, HIV-1, HIV-2, and SIV(SM) Vpr proteins function in both simian and human cell types, although SIV(SM) Vpr functions more efficiently in simian cells than it does in human cells. Neither differential protein stability nor subcellular localization explains the species-specific activities of these proteins. These results thus suggest that Vpr exerts its G2 arrest function by interacting with cellular factors that have evolved differently among the various primate species.     

The Orphan Seven-Transmembrane Receptor Apj Supports the Entry of Primary T-Cell-Line-Tropic and Dualtropic Human Immunodeficiency Virus Type 1

Human immunodeficiency virus type 1 (HIV-1) enters target cells by sequential binding to CD4 and specific seven-transmembrane-segment (7TMS) coreceptors. Viruses use the chemokine receptor CCR5 as a coreceptor in the early, asymptomatic stages of HIV-1 infection but can adapt to the use of other receptors such as CXCR4 and CCR3 as the infection proceeds. Here we identify one such coreceptor, Apj, which supported the efficient entry of several primary T-cell-line tropic (T-tropic) and dualtropic HIV-1 isolates and the simian immunodeficiency virus SIVmac316. Another 7TMS protein, CCR9, supported the less efficient entry of one primary T-tropic isolate. mRNAs for both receptors were present in phytohemagglutinin- and interleukin-2-activated peripheral blood mononuclear cells. Apj and CCR9 share with other coreceptors for HIV-1 and SIV an N-terminal region rich in aromatic and acidic residues. These results highlight properties common to 7TMS proteins that can function as HIV-1 coreceptors, and they may contribute to an understanding of viral evolution in infected individuals.     

Primary Human Immunodeficiency Virus Type 2 (HIV-2) Isolates Infect CD4-Negative Cells via CCR5 and CXCR4: Comparison with HIV-1 and Simian Immunodeficiency Virus and Relevance to Cell Tropism In Vivo

Cell surface receptors exploited by human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) for infection are major determinants of tropism. HIV-1 usually requires two receptors to infect cells. Gp120 on HIV-1 virions binds CD4 on the cell surface, triggering conformational rearrangements that create or expose a binding site for a seven-transmembrane (7TM) coreceptor. Although HIV-2 and SIV strains also use CD4, several laboratory-adapted HIV-2 strains infect cells without CD4, via an interaction with the coreceptor CXCR4. Moreover, the envelope glycoproteins of SIV of macaques (SIV(MAC)) can bind to and initiate infection of CD4(-) cells via CCR5. Here, we show that most primary HIV-2 isolates can infect either CCR5(+) or CXCR4(+) cells without CD4. The efficiency of CD4-independent infection by HIV-2 was comparable to that of SIV, but markedly higher than that of HIV-1. CD4-independent HIV-2 strains that could use both CCR5 and CXCR4 to infect CD4(+) cells were only able to use one of these receptors in the absence of CD4. Our observations therefore indicate (i) that HIV-2 and SIV envelope glycoproteins form a distinct conformation that enables contact with a 7TM receptor without CD4, and (ii) the use of CD4 enables a wider range of 7TM receptors to be exploited for infection and may assist adaptation or switching to new coreceptors in vivo. Primary CD4(-) fetal astrocyte cultures expressed CXCR4 and supported replication by the T-cell-line-adapted ROD/B strain. Productive infection by primary X4 strains was only triggered upon treatment of virus with soluble CD4. Thus, many primary HIV-2 strains infect CCR5(+) or CXCR4(+) cell lines without CD4 in vitro. CD4(-) cells that express these coreceptors in vivo, however, may still resist HIV-2 entry due to insufficient coreceptor concentration on the cell surface to trigger fusion or their expression in a conformation nonfunctional as a coreceptor. Our study, however, emphasizes that primary HIV-2 strains carry the potential to infect CD4(-) cells expressing CCR5 or CXCR4 in vivo.     

Electron tomography of the contact between T cells and SIV/HIV-1: implications for viral entry

The envelope glycoproteins of primate lentiviruses, including human and simian immunodeficiency viruses (HIV and SIV), are heterodimers of a transmembrane glycoprotein (usually gp41), and a surface glycoprotein (gp120), which binds CD4 on target cells to initiate viral entry. We have used electron tomography to determine the three-dimensional architectures of purified SIV virions in isolation and in contact with CD4+ target cells. The trimeric viral envelope glycoprotein surface spikes are heterogeneous in appearance and typically approximately 120 A long and approximately 120 A wide at the distal end. Docking of SIV or HIV-1 on the T cell surface occurs via a neck-shaped contact region that is approximately 400 A wide and consistently consists of a closely spaced cluster of five to seven rod-shaped features, each approximately 100 A long and approximately 100 A wide. This distinctive structure is not observed when viruses are incubated with T lymphocytes in the presence of anti-CD4 antibodies, the CCR5 antagonist TAK779, or the peptide entry inhibitor SIVmac251 C34. For virions bound to cells, few trimers were observed away from this cluster at the virion-cell interface, even in cases where virus preparations showing as many as 70 envelope glycoprotein trimers per virus particle were used. This contact zone, which we term the "entry claw", provides a spatial context to understand the molecular mechanisms of viral entry. Determination of the molecular composition and structure of the entry claw may facilitate the identification of improved drugs for the inhibition of HIV-1 entry.