New multiple antigenic peptide-based enzyme immunoassay for detection of simian immunodeficiency virus infection in nonhuman primates and humans

Genetic characterization of near full length SIVdrl genomes from four captive drills (Mandrillus leucophaeus)

We sequenced near full length SIVdrl genomes from four captive drills (Mandrillus leucophaeus). All four animals were born in captivity in German zoos. Although serologically SIV negative before acquisition in zoo A in 2008 and 2009, during a routine analysis all four animals were determined to be SIV antibody positive in 2011. Comparisons of the four new SIVdrl sequences showed high identity among each other (90.7-97.7% in env) and to the only published full length sequence SIVdrl FAO (90.5-92.8% in env), which is also derived from a captive drill. SIVdrl infections seem to be highly prevalent in captive drills, probably resulting from frequent animal transfers between the zoos in an effort to maintain this highly endangered species and its genetic diversity. This should be kept in mind as SIVdrl may be transmitted to uninfected animals in open groups and potentially also to animal keepers having contact with these nonhuman primates.

Discovery and full genome characterization of two highly divergent simian immunodeficiency viruses infecting black-and-white colobus monkeys (Colobus guereza) in Kibale National Park, Uganda

Background

African non-human primates (NHPs) are natural hosts for simian immunodeficiency viruses (SIV), the zoonotic transmission of which led to the emergence of HIV-1 and HIV-2. However, our understanding of SIV diversity and evolution is limited by incomplete taxonomic and geographic sampling of NHPs, particularly in East Africa. In this study, we screened blood specimens from nine black-and-white colobus monkeys (Colobus guereza occidentalis) from Kibale National Park, Uganda, for novel SIVs using a combination of serology and “unbiased” deep-sequencing, a method that does not rely on genetic similarity to previously characterized viruses.

Results

We identified two novel and divergent SIVs, tentatively named SIVkcol-1 and SIVkcol-2, and assembled genomes covering the entire coding region for each virus. SIVkcol-1 and SIVkcol-2 were detected in three and four animals, respectively, but with no animals co-infected. Phylogenetic analyses showed that SIVkcol-1 and SIVkcol-2 form a lineage with SIVcol, previously discovered in black-and-white colobus from Cameroon. Although SIVkcol-1 and SIVkcol-2 were isolated from the same host population in Uganda, SIVkcol-1 is more closely related to SIVcol than to SIVkcol-2. Analysis of functional motifs in the extracellular envelope glycoprotein (gp120) revealed that SIVkcol-2 is unique among primate lentiviruses in containing only 16 conserved cysteine residues instead of the usual 18 or more.

Conclusions

Our results demonstrate that the genetic diversity of SIVs infecting black-and-white colobus across equatorial Africa is greater than previously appreciated and that divergent SIVs can co-circulate in the same colobine population. We also show that the use of “unbiased” deep sequencing for the detection of SIV has great advantages over traditional serological approaches, especially for studies of unknown or poorly characterized viruses. Finally, the detection of the first SIV containing only 16 conserved cysteines in the extracellular envelope protein gp120 further expands the range of functional motifs observed among SIVs and highlights the complex evolutionary history of simian retroviruses.

Multiple antigenic peptide (MAP): a synthetic peptide dendrimer for diagnostic, antiviral and vaccine strategies for emerging and re-emerging viral diseases

The peptide dendrimer provides novel strategies for various biological applications. Assembling of peptide in macromolecular structure is expected to give rational models as drugs, their delivery and diagnostic reagents. Improved understanding of virus structure and their molecular interactions with ligands have paved the way for treatment and control of emerging and re-emerging viral diseases. This review presents a brief account of a synthetic peptide dendrimer used for diagnostic, therapeutic and prophylactic applications. The designs comprise of multiple antigenic peptides which are being used as alternate synthetic antigens for different viruses.

Cross-species transmission of simian retroviruses: how and why they could lead to the emergence of new diseases in the human population

The HIV-1 group M epidemic illustrates the extraordinary impact and consequences resulting from a single zoonotic transmission. Exposure to blood or other secretions of infected animals, through hunting and butchering of bushmeat, or through bites and scratches inflicted by pet nonhuman primates (NHPs), represent the most plausible source for human infection with simian immunodeficiency virus (SIV), simian T-cell lymphotropic virus (STLV) and simian foamy virus. The chance for cross-species transmissions could increase when frequency of exposure and retrovirus prevalence is high. According to the most recent data, human exposure to SIV or STLV appears heterogeneous across the African countries surveyed. Exposure is not sufficient to trigger disease: viral and host molecular characteristics and compatibility are fundamental factors to establish infection. A successful species jump is achieved when the pathogen becomes transmissible between individuals within the new host population. To spread efficiently, HIV likely required changes in human behavior. Given the increasing exposure to NHP pathogens through hunting and butchering, it is likely that SIV and other simian viruses are still transmitted to the human population. The behavioral and socio-economic context of the twenty-first century provides favorable conditions for the emergence and spread of new epidemics. Therefore, it is important to evaluate which retroviruses the human population is exposed to and to better understand how these viruses enter, infect, adapt and spread to its new host.

Failure to detect simian immunodeficiency virus infection in a large Cameroonian cohort with high non-human primate exposure

Hunting and butchering of wildlife in Central Africa are known risk factors for a variety of human diseases, including HIV/AIDS. Due to the high incidence of human exposure to body fluids of non-human primates, the significant prevalence of simian immunodeficiency virus (SIV) in non-human primates, and hunting/butchering associated cross-species transmission of other retroviruses in Central Africa, it is possible that SIV is actively transmitted to humans from primate species other than mangabeys, chimpanzees, and/or gorillas. We evaluated SIV transmission to humans by screening 2,436 individuals that hunt and butcher non-human primates, a population in which simian foamy virus and simian T-lymphotropic virus were previously detected. We identified 23 individuals with high seroreactivity to SIV. Nucleic acid sequences of SIV genes could not be detected, suggesting that SIV infection in humans could occur at a lower frequency than infections with other retroviruses, including simian foamy virus and simian T-lymphotropic virus. Additional studies on human populations at risk for non-human primate zoonosis are necessary to determine whether these results are due to viral/host characteristics or are indicative of low SIV prevalence in primate species consumed as bushmeat as compared to other retroviruses in Cameroon.

Novel multiplexed HIV/simian immunodeficiency virus antibody detection assay

Like most emerging infectious disease viruses, HIV is also of zoonotic origin. To assess the risk for cross-species transmission of simian immunodeficiency viruses (SIVs) from nonhuman primates to humans in the Democratic Republic of Congo, we collected 330 samples derived from nonhuman primate bushmeat at 3 remote forest sites. SIV prevalences were estimated by using a novel high-throughput assay that included 34 HIV and SIV antigens in a single well. Overall, 19% of nonhuman primate bushmeat was infected with SIVs, and new SIV lineages were identified. Highest SIV prevalences were seen in red-tailed guenons (25%) and Tshuapa red colobus monkeys (24%), representing the most common hunted primate species, thus increasing the likelihood for cross-species transmission. Additional studies are needed to determine whether other SIVs crossed the species barrier. With the newly developed assay, large-scale screening against many antigens is now easier and faster.

Extensive survey on the prevalence and genetic diversity of SIVs in primate bushmeat provides insights into risks for potential new cross-species transmissions

To evaluate the risk of cross-species transmissions of SIVs from non-human primates to humans at the primate/hunter interface, a total of 2586 samples, derived from primate bushmeat representing 11 different primate species, were collected at 6 distinct remote forest sites in southeastern Cameroon and in Yaoundé, the capital city. SIV prevalences were estimated with an updated SIV lineage specific gp41 peptide ELISA covering the major part of the SIV diversity. SIV positive samples were confirmed by PCR and sequence analysis of partial pol fragments. The updated SIV ELISA showed good performance with overall sensitivity and specificity of 96% and 97.5% respectively. The overall SIV seroprevalence was low, 2.93% (76/2586) and ranged between 0.0% and 5.7% at forest sites, and reached up to 10.3% in Yaoundé. SIV infection was documented in 8 of the 11 species with significantly different prevalence rates per species: 9/859 (1.0%) in Cercopithecus nictitans, 9/864 (1.0%) Cercopithecus cephus, 10/60 (16.7%) Miopithecus ogouensis, 14/78 (17.9%) Colobus guereza, 15/37 (40.5%) Cercopithecus neglectus, 10/27 (33.3%) Mandrillus sphinx, 6/12 (50%) Cercocebus torquatus, and 3/6 (50%) Chlorocebus tantalus. No SIV infection was identified in Cercopithecus pogonias (n=293), Lophocebus albigena (n=168) and Cercocebus agilis (n=182). The SIV prevalences also seem to vary within species according to the sampling site, but most importantly, the highest SIV prevalences are observed in the primate species which represent only 8.5% of the overall primate bushmeat. The phylogenetic tree of partial pol sequences illustrates the high genetic diversity of SIVs between and within different primate species. The tree also showed some interesting features within the SIVdeb lineage suggesting phylogeographic clusters. Overall, the risk for additional cross-species transmissions is not equal throughout southern Cameroon and depends on the hunted species and SIV prevalences in each species. However, humans are still exposed to a high diversity of SIVs as illustrated by the high inter and intra SIV lineage genetic diversity.

Genetic diversity of simian lentivirus in wild De Brazza's monkeys (Cercopithecus neglectus) in Equatorial Africa

De Brazza’s monkeys (Cercopithecus neglectus) are non-human primates (NHP) living in Equatorial Africa from South Cameroon through the Congo-Basin to Uganda. As most of the NHP living in sub-Saharan Africa, they are naturally infected with their own simian lentivirus, SIVdeb. Previous studies confirmed this infection for De Brazza’s from East Cameroon and Uganda. In this report, we studied the genetic diversity of SIVdeb in De Brazza’s monkeys from different geographical areas in South Cameroon and from the Democratic Republic of Congo (DRC). SIVdeb strains from east, central and western equatorial Africa form a species-specific monophyletic lineage. Phylogeographic clustering was observed among SIVdeb strains from Cameroon, the DRC and Uganda, but also among primates from distinct areas in Cameroon. These observations suggest a longstanding virus–host co-evolution. SIVdeb prevalence is high in wild De Brazza’s populations and thus represents a current risk for humans exposed to these primates in central Africa.

Coinfection of Ugandan red colobus (Procolobus [Piliocolobus] rufomitratus tephrosceles) with novel, divergent delta-, lenti-, and spumaretroviruses

Nonhuman primates host a plethora of potentially zoonotic microbes, with simian retroviruses receiving heightened attention due to their roles in the origins of human immunodeficiency viruses type 1 (HIV-1) and HIV-2. However, incomplete taxonomic and geographic sampling of potential hosts, especially the African colobines, has left the full range of primate retrovirus diversity unexplored. Blood samples collected from 31 wild-living red colobus monkeys (Procolobus [Piliocolobus] rufomitratus tephrosceles) from Kibale National Park, Uganda, were tested for antibodies to simian immunodeficiency virus (SIV), simian T-cell lymphotrophic virus (STLV), and simian foamy virus (SFV) and for nucleic acids of these same viruses using genus-specific PCRs. Of 31 red colobus tested, 22.6% were seroreactive to SIV, 6.4% were seroreactive to STLV, and 97% were seroreactive to SFV. Phylogenetic analyses of SIV polymerase (pol), STLV tax and long terminal repeat (LTR), and SFV pol and LTR sequences revealed unique SIV and SFV strains and a novel STLV lineage, each divergent from corresponding retroviral lineages previously described in Western red colobus (Procolobus badius badius) or black-and-white colobus (Colobus guereza). Phylogenetic analyses of host mitochondrial DNA sequences revealed that red colobus populations in East and West Africa diverged from one another approximately 4.25 million years ago. These results indicate that geographic subdivisions within the red colobus taxonomic complex exert a strong influence on retroviral phylogeny and that studying retroviral diversity in closely related primate taxa should be particularly informative for understanding host-virus coevolution.

Implications of simian retroviruses for captive primate population management and the occupational safety of primate handlers

Nonhuman primates can be naturally infected with a plethora of viruses with zoonotic potential, including retroviruses. These simian viruses present risks to both captive nonhuman primate populations and persons exposed to nonhuman primates. Simian retroviruses, including simian immunodeficiency virus, simian type D retrovirus, simian T-lymphotropic virus, and gibbon ape leukemia virus, have been shown to cause clinical disease in nonhuman primates. In contrast, simian foamy virus, a retrovirus that is highly prevalent in most nonhuman primates, has not been associated with clinical disease in naturally infected primates. Although it has been shown that human retrovirus infections with human T-lymphotropic virus and human immunodeficiency virus originated through multiple independent introductions of simian retroviruses into human populations that then spread globally, little is known about the frequency of such zoonotic events. In this article, exogenous simian retroviruses are reviewed as a concern for zoo and wildlife veterinarians, primate handlers, other persons in direct contact with nonhuman primates, and other nonhuman primates in a collection. The health implications for individual animals as well as managed populations in zoos and research institutions are discussed, the cross-species transmission and zoonotic disease potential of simian retroviruses are described, and suggestions for working safely with nonhuman primates are provided.

Chimeric multiple antigenic peptides for simultaneous detection of specific antibodies to HIV-1 groups M, N, O, and HIV-2

Synthetic peptides have frequently replaced the more costly recombinant proteins or viral lysates as the antigens of choice for detection of antibodies to human immunodeficiency viruses. However, development of an assay that is sensitive to all the types and groups of HIV, including the divergent strains of HIV-1 group O, group N, and HIV-2, would require many peptides derived from different types and groups of HIV. Combining multiple peptide antigens may reduce the analytical sensitivity of the individual peptide due to the competition for binding to the solid surface when used in an enzyme immunoassay format. In this study, we developed and evaluated two chimeric multiple antigenic peptides (CMAP) for simultaneous detection of specific antibodies to HIV-1 groups M, N, O, and HIV-2. Both CMAPs correctly identified 304 known HIV positive serum or plasma specimens (260 HIV-1 group M of varying subtypes, 3 group O, and 41 HIV-2) and one chimpanzee serum specimen (group N) and all 66 known HIV negative specimens. CMAP performance was superior to the corresponding individual linear peptides or a linear peptide mixture. The results indicate that CMAPs are useful for the development of highly sensitive and specific assays for the detection of infections caused by HIV-1, including group M, N, and O, and HIV-2.

A Simple Parallel Analytical Method of Prenatal Screening

Protein microarray has progressed rapidly in the past few years, but it is still hard to popularize it in many developing countries or small hospitals owing to the technical expertise required in practice. We developed a cheap and easy-to-use protein microarray based on dot immunogold filtration assay for parallel analysis of ToRCH-related antibodies including Toxoplasma gondii, rubella virus, cytomegalovirus and herpes simplex virus type 1 and 2 in sera of pregnant women. It does not require any expensive instruments and the assay results can be clearly recognized by the naked eye. We analyzed 186 random sera of outpatients at the gynecological department with our microarray and commercial ELISA kit, and the results showed there was no significant difference between the two detection methods. Validated by clinical application, the microarray is easy to use and has a unique advantage in cost and time. It is more suitable for mass prenatal screening or epidemiological screening than the ELISA format.

Central African hunters exposed to simian immunodeficiency virus

HIV-seronegative Cameroonians with exposure to nonhuman primates were tested for simian immunodeficiency virus (SIV) infection. Seroreactivity was correlated with exposure risk (p<0.001). One person had strong humoral and weak cellular immune reactivity to SIVcol peptides. Humans are exposed to and possibly infected with SIV, which has major public health implications.

Molecular characterization of a novel simian immunodeficiency virus lineage (SIVtal) from northern talapoins (Miopithecus ogouensis)

Simian immunodeficiency viruses (SIVs) are found in an extensive number of African primates, and humans continue to be exposed to these viruses by hunting and handling of primate bushmeat and following occupational exposures to captive nonhuman primates. Here, we report the molecular characterization of a new SIV lineage, SIVtal, from wild-caught and captive talapoin monkeys (Miopithecus ogouensis) from Cameroon and U.S. zoos, respectively. Phylogenetic tree analyses of a small fragment in the pol gene indicated that all SIVtal strains clustered together forming a single species-specific lineage. Full-length sequence analysis for two strains, SIVtal-00CM266 and SIVtal-01CM8023, from wild-caught animals in Cameroon confirmed that SIVtal was distinct from all primate lentiviruses isolated so far and represents a new SIV lineage. Phylogenetic analyses in different viral genes showed a significant clustering of the SIVtal lineage with the Cercopithecus-specific SIVs. In addition, SIVtal and Cercopithecus-specific SIVs share functional motifs in Gag and Env that distinguish them from other primate lentiviruses. Like SIVsyk and SIVdeb, a vpu gene homologue was also absent in SIVtal. Although northern talapoins belong to the Miopithecus genus, their SIVs belong to the Cercopithecus SIV lineage, suggesting evolution from a common ancestor or cross-species transmission between both primate genera.

Widely varying SIV prevalence rates in naturally infected primate species from Cameroon

Although it is now well established that a substantial proportion of wild-living primates in sub-Saharan Africa harbor SIV, no study to date has examined to what extent the various species are naturally infected. In this study, we first describe the development and validation of sensitive and specific SIV antibody detection assays representing all major known primate lentiviral lineages on a panel of 207 sera from 11 different primate species with known infection status. The newly developed assays were then used to determine SIV prevalence rates in nine primate species native to Cameroon. Analysis of 722 sera revealed widely varying prevalence rates, ranging from an apparent absence of SIV infection in crested mona (0/70), grey cheeked (0/36) and agile mangabeys (0/92), to prevalence rates of 3%, 4%, 11%, 27%, 39% and 52% for mustached (6/203), greater spot-nosed (8/193), northern talapoin (3/26), mantled guereza (14/52), De Brazza's (9/23) and mandrill (14/27) monkeys, respectively. The epidemiology of naturally occurring SIV infections is thus more complex than previously appreciated and the various non-human primate hosts seem to differ in their susceptibility to SIV infection. The newly developed assays should now permit to define with greater accuracy existing SIV reservoirs and associated human zoonotic risk.

Peptide dendrimers

Dendrimers are branched structures and represent a fast growing field covering many areas of chemistry. Various types of dendrimers differing in composition and structure are mentioned, together with their practical use spanning from catalysis, transport vehicles to synthetic vaccines. The main stress is given to peptide dendrimers, namely, multiple antigenic peptides (MAPs). Their synthesis, physicochemical properties, biological activities, etc. have been described with many examples. MAPs can be used as diagnostics, mimetics, for complexation of different cations, as vaccines against parasites, bacteria, viruses, etc.