Isolation and characterization of simian immunodeficiency virus from African white-crowned mangabey monkeys (Cercocebus torquatus lunulatus)

While simian immunodeficiency viruses (SIVs) are generally nonpathogenic in their natural hosts, dramatic increases in pathogenicity may occur upon cross-species transmission to new hosts. Deciphering the drivers of these increases in virulence is of major interest for understanding the emergence of new human immunodeficiency viruses (HIVs). We transmitted SIVsab from the sabaeus species of African green monkeys (AGMs) to pigtailed macaques (PTMs). High acute viral replication occurred in all SIVsab-infected PTMs, yet the outcome of chronic infection was highly variable, ranging from rapid progression to controlled infection, which was independent of the dynamics of acute viral replication, CD4؉ T cell depletion, or preinfection levels of microbial translocation. Infection of seven PTMs with plasma collected at necropsy from a rapid-progressor PTM was consistently highly pathogenic, with high acute and chronic viral replication, massive depletion of memory CD4 ؉ T cells, and disease progression in all PTMs. The plasma inoculum used for the serial passage did not contain adventitious bacterial or viral contaminants. Single-genome amplification showed that this inoculum was significantly more homogenous than the inoculum directly derived from AGMs, pointing to a strain selection in PTMs. In spite of similar peak plasma viral loads between the monkeys in the two passages, immune activation/inflammation levels dramatically increased in PTMs infected with the passaged virus. These results suggest that strain selection and a massive cytokine storm are major factors behind increased pathogenicity of SIV upon serial passage and adaptation of SIVs to new hosts following cross-species transmission. IMPORTANCEWe report here that upon cross-species transmission and serial passage of SIVsab from its natural host, the sabaeus African green monkey (AGM), to a new host, the pigtailed macaque (PTM), viral adaptation and increased pathogenicity involve strain selection and a massive cytokine storm. These results permit the design of strategies aimed at preventing cross-species transmission from natural hosts of SIVs to humans in areas of endemicity. Furthermore, our study describes a new animal model for SIV infection. As the outcomes of SIVsab infection in PTMs, African green monkeys, and rhesus macaques are different, the use of these systems enables comparative studies between pathogenic, nonpathogenic, and elite-controlled infections, to gain insight into the mechanisms of SIV immunodeficiency and comorbidities.

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confidence: 99%

Pathogenic Features Associated with Increased Virulence upon Simian Immunodeficiency Virus Cross-Species Transmission from Natural Hosts

Mandell

Kristoff

Gaufin

et al. 2014

“…They form at least eight phylogenetic lineages (3,11,20) and have evolved through host-dependent evolution (1,9,27,45,57), cross-species transmissions (12,37,62,65), recombinations (4,10,28,35,36,61), and preferential host switching (17). This highly divergent group of viruses may represent a significant threat for crossspecies transmission to humans, as shown by the fact that both human immunodeficiency virus type1 (HIV-1) and HIV-2 have originated from cross-species transmission from two different simian sources: chimpanzee for HIV-1 (27) and sooty-mangabey (SM) for HIV-2 (18).…”

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confidence: 99%

Primary Simian Immunodeficiency Virus SIVmnd-2 Infection in Mandrills ( Mandrillus sphinx )

Onanga

Souquière

Makuwa

et al. 2006

Mandrills are the only nonhuman primate (NHP) naturally infected by two types of simian immunodeficiency virus (SIV): SIVmnd-1 and SIVmnd-2. We have already reported that the high SIVmnd-1 replication during primary infection contrasts with only transient changes in CD4؉ and CD8 ؉ cell counts. Since early virus-host interactions predict viral control and disease progression in human immunodeficiency virusinfected patients, we investigated the dynamics of SIVmnd-2 primary infection in mandrills to examine the impact on immune effectors in blood and lymph nodes (LNs). To avoid in vitro strain selection, all mandrills in this study received plasma from SIVmnd-2-infected mandrills. SIVmnd-2 plasma viremia peaked at 10 7 to 10 8 RNA copies/ml between days 7 and 10. This peak was followed in all four monkeys by a decline in virus replication, with a set point level of 10 5 to 10 6 RNA copies/ml at day 42 postinfection (p.i.). Viral DNA load in PBMC and LNs also peaked between days 7 and 10 (10 5 to 10 6 DNA copies/10 6 cells) and stabilized at 10 3 to 10 4 DNA copies/10 6 cells during the chronic phase. Anti-SIVmnd-2 antibodies were detected starting from days 28 to 32. A transitory decline of CD3 ؉ CD4 ؉ cells in the LNs occurred in animals with high peak VLs. CD4؉ and CD8 ؉ T-cell activation in blood and LNs was noted between days 5 and 17 p.i., surrounding the peak of viral replication. This was most significant in the LNs. Activation markers then returned to preinfection values despite continuous and active viral replication during the chronic infection. The dynamics of SIVmnd-2 infection in mandrills showed a pattern similar to that of SIVmnd-1 infection. This might be a general feature of nonpathogenic SIV natural African NHP models.

“…However, in many cases the differences between phylogenetic relationships of some viruses and primate phylogeny indicated that there have been multiple crossspecies transmissions in the past (7,28,51). Cross-species transmission of PLVs can have a variety of outcomes in the new host.…”

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confidence: 99%

Characterization and Comparison of Recombinant Simian Immunodeficiency Virus from Drill ( Mandrillus leucophaeus ) and Mandrill ( Mandrillus sphinx ) Isolates

Switzer

Foley

et al. 2003

Since simian immunodeficiency virus (SIV) was found to be the source of the human AIDS pandemic, a major goal has been to characterize the diversity of SIV strains in the wild and to assess their potential for crossover into humans. In the present study, SIV was isolated from a seropositive drill (Mandrillus leucophaeus) and three seropositive mandrills (Mandrillus sphinx) by using macaque peripheral blood mononuclear cells (PBMC). Full-length sequences were obtained from a drill and mandrill and designated SIVdrl1FAO and SIVmnd5440, respectively. A 182-bp fragment of the pol genes of the two remaining mandrill SIV isolates was also analyzed. Phylogenetic analyses demonstrated that SIVdrl1FAO formed a monophyletic clade with SIVmnd5440 and SIVmndM14, recently designated SIVmnd type 2. Both the SIVdrl and SIVmnd type 2 genomes carried a vpx gene and appeared to share a common ancestor with SIVrcm in the 5 region of the genome and with SIVmndGB1 (type 1) in the 3 region of the genome. A statistically significant recombination breakpoint was detected at the beginning of envelope, suggesting that the viruses were descendents of the same recombinant. Phylogenetic analysis of vpx and vpr genes demonstrated that the vpx genes formed a monophyletic cluster that grouped with vpr from SIVagm. In addition, both SIVdrl1FAO and SIVmnd5440 replicated in human PBMC and therefore could pose a risk of transmission to the human population.