Additional files 1: Figure S1 . A plot of the values of the Axis1a (20.82%) and the Axis2a (16.27%) of each ORF in principle component analysis. Novel, Divergent Simian Hemorrhagic Fever Viruses in a Wild Ugandan Red Colobus Monkey Discovered Using Direct Pyrosequencing BACKGROUND: Simian hemorrhagic fever virus (SHFV) has caused lethal outbreaks of hemorrhagic disease in captive primates, but its distribution in wild primates has remained obscure. Here, we describe the discovery and genetic characterization by direct pyrosequencing of two novel, divergent SHFV variants co-infecting a single male red colobus monkey from Kibale National Park, Uganda. METHODOLOGY/PRINCIPAL FINDINGS: The viruses were detected directly from blood plasma using pyrosequencing, without prior virus isolation and with minimal PCR amplification. The two new SHFV variants, SHFV-krc1 and SHFV-krc2 are highly divergent from each other (51.9% nucleotide sequence identity) and from the SHFV type strain LVR 42-0/M6941 (52.0% and 51.8% nucleotide sequence identity, respectively) and demonstrate greater phylogenetic diversity within SHFV than has been documented within any other arterivirus. Both new variants nevertheless have the same 3′ genomic architecture as the type strain, containing three open reading frames not present in the other arteriviruses. CONCLUSIONS/SIGNIFICANCE: These results represent the first documentation of SHFV in a wild primate and confirm the unusual 3′ genetic architecture of SHFV relative to the other arteriviruses. They also demonstrate a degree of evolutionary divergence within SHFV that is roughly equivalent to the degree of divergence between other arterivirus species. The presence of two such highly divergent SHFV variants co-infecting a single individual represents a degree of within-host viral diversity that exceeds what has previously been reported for any arterivirus. These results expand our knowledge of the natural history and diversity of the arteriviruses and underscore the importance of wild primates as reservoirs for novel pathogens. Simian hemorrhagic fever virus (SHFV) was discovered during an ''explosive'' outbreak of hemorrhagic disease in rhesus macaques (Macaca mulatta) in 1964 [1] . Since then, sporadic epidemics have occurred in macaques, likely as a result of contact with, or iatrogenic transmission from, infected but asymptomatic captive African monkeys [2, 3, 4] . Viruses related to SHFV have not yet been found to infect humans, but the clinical manifestations of SHFV resemble those of other primate-associated hemorrhagic fever viruses significant for human health (e.g. Ebola, Marburg, Yellow fever), making SHFV of interest with respect to emerging infectious disease surveillance and biodefense [4, 5] . Although asymptomatic SHFV infections in captive patas monkeys (Erythrocebus patas), vervet monkeys (Cercopithecus aethiops), and baboons (Papio sp.) suggest that such species could be natural SHFV reservoirs [2, 3] , the virus has never, to our knowledge, been found in a primate in the wild.