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In July 2019, a vaccine-derived recombinant Porcine reproductive and respiratory syndrome virus 1 strain (PRRSV-1) (Horsens strain) infected more than 40 Danish sow herds, resulting in severe losses. In the present study, the pathogenicity of the recombinant Horsens strain was assessed and compared to a reference PRRSV-1 strain using a well-characterized experimental model in young SPF pigs. Furthermore, the efficacies of three different PRRSV-1 MLV vaccines to protect pigs against challenge with the recombinant strain were assessed. Following challenge, the unvaccinated pigs challenged with the Horsens strain had significant increased viral load in serum compared to all other groups. No macroscopic changes were observed at necropsy, but tissue from the lungs and tonsils from almost all pigs were PRRSV-positive. The viral load in serum was lower in all vaccinated groups compared to the unvaccinated group challenged with the Horsens strain, and only small differences were seen among the vaccinated groups. The findings in the present study, combined with two other recent reports, indicate that this recombinant “Horsens” strain indeed is capable of inducing infection in growing pigs as well as in pregnant sows that is comparable to or even exceeding those induced by typical PRRSV-1, subtype 1 strains. However, absence of notable clinical signs and lack of significant macroscopic changes indicate that this strain is less virulent than previously characterized highly virulent PRRSV-1 strains.

European PRRS Research Award 2017Juillette Bougon received a PhD thesis fellowship from Université de Rennes (UNIR), France, in the framework of grant agreements with Région Bretagne, Conseil Départemental des Côtes d’Armor and Saint-Brieuc Armor Agglomération, France; International audience; Modified-live vaccines (MLVs) against porcine reproductive and respiratory syndrome viruses (PRRSVs) are usually administrated to piglets at weaning when swine influenza A virus (swIAV) infections frequently occur. SwIAV infection induces a strong interferon alpha (IFNa) response and IFNa was shown to abrogate PRRSV2 MLV replication and an inherent immune response. In this study, we evaluated the impacts of swIAV infection on the replication of a PRRSV1 MLV (MLV1), post-vaccine immune responses and post-challenge vaccine efficacy at both the systemic and pulmonary levels. Piglets were either swIAV inoculated and MLV1 vaccinated 6 h apart or singly vaccinated or mock inoculated and mock vaccinated. Four weeks after vaccination, the piglets were challenged with a PRRSV1 field strain. The results showed that swIAV infection delayed MLV1 viremia by six days and post-vaccine seroconversion by four days. After the PRRSV1 challenge, the swIAV enhanced the PRRSV1-specific cell-mediated immunity (CMI) but the PRRSV1 field strain viremia was not better controlled. High IFNa levels that were detected early after swIAV infection could have been responsible for both the inhibition of MLV1 replication and CMI enhancement. Thus, whereas swIAV infection had a negative impact on humoral responses post-vaccination, it did not interfere with the protective effectiveness of the PRRSV MLV1 in our experimental conditions.

International audience; Respiratory infections are still a major concern in pigs. Amongst the involved viruses, the porcine reproductive and respiratory syndrome virus (PRRSV) and the swine influenza type A virus (swIAV) have a major impact. These viruses frequently encounter and dual infections are reported. We analyzed here the molecular interactions between viruses and porcine tracheal epithelial cells as well as lung tissue. PRRSV-1 species do not infect porcine respiratory epithelial cells. However, PRRSV-1, when inoculated simultaneously or shortly before swIAV, was able to inhibit swIAV H1N2 infection, modulate the interferon response and alter signaling protein phosphorylations (ERK, AKT, AMPK, and JAK2), in our conditions. SwIAV inhibition was also observed, although at a lower level, by inactivated PRRSV-1, whereas acid wash treatment inactivating non-penetrated viruses suppressed the interference effect. PRRSV-1 and swIAV may interact at several stages, before their attachment to the cells, when they attach to their receptors, and later on. In conclusion, we showed for the first time that PRRSV can alter the relation between swIAV and its main target cells, opening the doors to further studies on the interplay between viruses. Consequences of these peculiar interactions on viral infections and vaccinations using modified live vaccines require further investigations.

WOS:000467333800001; International audience; Swine lymph nodes (LN) present an inverted structure compared to mouse and human, with the afferent lymph diffusing from the center to the periphery. This structure, also observed in close and distant species such as dolphins, hippopotamus, rhinoceros, and elephants, is poorly described, nor are the LN macrophage populations and their relationship with B cell follicles. B cell maturation occurs mainly in LN B cell follicles with the help of LN macrophage populations endowed with different antigen delivery capacities. We identified three macrophage populations that we localized in the inverted LN spatial organization. This allowed us to ascribe porcine LN M 8 to their murine counterparts: subcapsular sinus M 8, medullary cord M 8 and medullary sinus M 8. We identified the different intra and extrafollicular stages of LN B cells maturation and explored the interaction of M 8, drained antigen and follicular B cells. The porcine reproductive and respiratory syndrome virus (PRRSV) is a major porcine pathogen that infects tissue macrophages (M 8). PRRSV is persistent in the secondary lymphoid tissues and induces a delay in neutralizing antibodies appearance. We observed PRRSV interaction with two LN M 8 populations, of which one interacts closely with centroblasts. We observed BCL6 up-regulation in centroblast upon PRRSV infection, leading to new hypothesis on PRRSV inhibition of B cell maturation. This seminal study of porcine LN will permit fruitful comparison with murine and human LN for a better understanding of normal and inverted LN development and functioning.

The outputs of epidemiological models are strongly related to the structure of the model and input parameters. The latter are defined by fitting theoretical concepts to actual data derived from field or experimental studies. However, some parameters may remain difficult to estimate and are subject to uncertainty or sensitivity analyses to determine their variation range and their global impact on model outcomes. As such, the evaluation of immunity duration is often a puzzling issue requiring long-term follow-up data that are, most of time, not available. The present analysis aims at characterizing the kinetics of antibodies against Porcine Reproductive and Respiratory Syndrome virus (PRRSv) from longitudinal datasets. The first dataset consisted in the serological follow-up of 22 vaccinated gilts during 21 weeks post vaccination. The second one gathered the maternally derived antibody (MDA) kinetics in piglets from 3 different farms up to 14 weeks of age. The peak of the post-vaccination (PV) serological response against PRRSv was reached 6.9 weeks post-vaccination on average withan average duration of antibodies persistence of 26.5 weeks. In the monitored cohort of piglets, the duration of passive immunity was found relatively short, with an average duration of 4.8 weeks. The level of PRRSv-MDAs was found correlated with the dams’ antibody titer at birth and the antibody persistence was strongly related to the initial MDAs titers in piglets. These results evidenced the importance of PRRSv vaccination schedule in sows, to optimize the delivery of antibodies to suckling piglets. These estimates of the duration of active and passive immunity could be further used as input parameters of epidemiological models to analyze their impact on the persistence of PRRSV within farms.

Porcine reproductive and respiratory syndrome virus (PRRSV) replicates primarily in pulmonary alveolar macrophages (PAMs) and the resulting lung damage is influenced by strain virulence. To better understand the pathogenesis of PRRSV infection, we performed a longitudinal study of the PAM population and lung cytokines in specific pathogen-free pigs infected either with the highly pathogenic Lena strain or with the low pathogenic Finistere strain in comparison to uninfected pigs. Bronchoalveolar lavage fluid (BALF) and blood were collected to follow viral, cellular and cytokine changes in lung with respect to clinical signs and systemic events. Compared to Finistere-infected pigs, Lena-infected pigs exhibited more severe clinical signs and 10- to 100-fold higher viral loads in BALF and blood. Similarly, they showed an earlier drop in BALF cell viability and phagocytic activity along with a decrease in the macrophage count. From 8 to 15 days post-infection (dpi), monocytes increased both in BALF and blood from Lena-infected pigs. BALF and blood showed contrasting cytokine patterns, with low increase of IFN-α and TNF-α levels and high increase for IL-1α and IL-8 in BALF after Lena-infection. In contrast, in the blood, the increase was marked for IFN-α and TNF-α but limited for IL-1β and IL-8. Down-regulation of PAM functions combined with inflammatory cytokine and monocyte recruitment may promote lung pathogenesis and virus replication in PRRSV infections with the highly pathogenic Lena strain. In contrast, the low pathogenic Finistere strain showed prolonged viral replication in lung, possibly related to the weak IFN-γ response. Electronic supplementary material The online version of this article (doi:10.1186/s13567-017-0420-y) contains supplementary material, which is available to authorized users.

Author(s): Camus, Celine; Matusali, Giulia; Bourry, Olivier; Mahe, Dominique; Aubry, Florence; Bujan, Louis; Pasquier, Christophe; Massip, Patrice; Ravel, Celia; Zirafi, Onofrio; Munch, Jan; Roan, Nadia R; Pineau, Charles; Dejucq-Rainsford, Nathalie | Abstract: ObjectivesSemen composition is influenced by HIV-1 infection, yet the impact of semen components on HIV infection of primary target cells has only been studied in samples from HIV-uninfected donors.DesignWe compared the effect of seminal plasma (SP) from chronically HIV-infected (SP+) versus uninfected donors (SP-) on HIV-1 infection of peripheral blood mononuclear cells (PBMCs) and CD4 T cells.MethodsPrimary cells were infected with HIV-1 in the presence of SP+ or SP- and analyzed for infection level, metabolic activity, HIV receptor expression, proliferation and activation. SP+ and SP- were compared for infection-enhancing peptides, cytokines and prostaglandin E2 levels.ResultsSP- efficiently enhanced HIV-1 R5 infection of CD4 T cells, whereas SP+ enhancing activity was significantly reduced. RANTES (CCL5) concentrations were elevated in SP+ relative to SP-, whereas the concentrations of infectivity-enhancing peptides [semen-derived enhancer of viral infection (SEVI), SEM1, SEM2] were similar. CCR5 membrane expression levels were reduced on CD4 T cells shortly postexposure to SP+ compared with SP- and correlated to R5-tropic HIV-1 infection levels, and CCR5 ligands' concentrations in semen. SP+ and SP- displayed similar enhancing activity on PBMC infection by X4-tropic HIV-1. Addition/depletion of RANTES (regulated on activation, normal T-cell expressed and secreted) from SPs modulated their effect on PBMC infection by R5-tropic HIV-1.ConclusionSemen from HIV-infected donors exhibits a significantly reduced enhancing potential on CD4 T-cell infection by R5-tropic HIV-1 when compared with semen from uninfected donors. Our data indicate that elevated seminal concentrations of RANTES in HIV-infected men can influence the ability of semen to enhance infection.

The influence of maternally-derived antibodies (MDAs) on the post-vaccination humoral and cellular immune responses in piglets vaccinated against PRRS was studied. The piglets came from a vaccinated breeding herd. Thirty piglets with a low (A-) or high level (A+) of PRRSV-neutralizing MDAs were vaccinated (V+) with a modified live vaccine at 3 weeks of age. Blood samples were collected before vaccination and then at 2, 4, 8 and 14 weeks post-vaccination (WPV). The samples were analysed to detect the vaccine viraemia (RT-PCR) and quantify the post-vaccination humoral (ELISA and virus neutralisation test) and cellular (ELISPOT IFNγ) immune responses. PRRSV vaccine strain was detected in 60%, 64%, 36% and 0% of A-V+ piglets 2, 4, 8 and 14 WPV respectively. No virus was detected in A+V+ piglets during the first four WPV but 32% and 6% of A+V+ piglets were PCR-positive at 8 and 14 WPV. Eighty-five percent of A-V+ piglets and 0% of A+V+ piglets seroconverted (ELISA) between 2 and 4 WPV. Neutralising antibodies appeared 4 WPV in the A-V+ piglets and 14 WPV in the A+V+ piglets. The number of PRRSV-specific IFNγ-secreting cells was significantly higher in A-V+ piglets at 2 and 4 WPV than in A+V+ piglets. These results show that MDAs can affect both post-vaccination humoral and cellular immune responses in piglets. Further studies are required to assess the impact of MDAs on vaccine efficacy following a PRRSV challenge and its ability to reduce viral transmission.

To evaluate the efficacy of postexposure prophylaxis with a combination of zidovudine (ZDV), lamivudine (3TC) and indinavir (IDV), after vaginal exposure to HIV.: Experimental intravaginal exposure of female cynomolgus macaques to SIVmac251.ZDV/3TC/IDV treatment was initiated 4 h after exposure and continued for 28 days. Groups of six animals received a placebo or a combination of oral ZDV (4.5 mg/kg), 3TC (2.5 mg/kg) and IDV (20 mg/kg) twice daily or subcutaneous ZDV (4.5 mg/kg) and 3TC (2.5 mg/kg) twice daily, and a higher dose of IDV (60 mg/kg) administered orally twice daily.In the placebo group, all animals were infected. Antiretroviral association protected one of the six animals if all drugs were administered orally and four of the six animals if ZDV and 3TC were administered subcutaneously and IDV was given orally at triple dose. In infected animals, viremia was significantly delayed and lowered in treated animals than in animals given placebo, and high CD4 cell counts were maintained in the treated animals, at least in the medium term. Antiretroviral dosages made in macaques receiving the same treatments showed that protection efficacy could be linked to antiretroviral plasmatic concentration.This study shows, for the first time in macaques, that the postexposure prophylaxis recommended for humans may be effective after vaginal exposure. Improvements in pharmacokinetic parameters significantly increased treatment efficiency.

Porcine respiratory disease complex (PRDC) is one of the main causes of economic losses for swine producers. This complex is due to a combination of different pathogens and their interactions. Two major pathogens involved in PRDC are Mycoplasma hyopneumoniae (Mhp) and porcine reproductive and respiratory syndrome virus (PRRSV). The objectives of this study were (i) to develop an experimental model of dual Mhp/PRRSV infection in SPF pigs with European strains of Mhp and PRRSV and (ii) to assess and compare the effects of single Mhp, single PRRSV or combined Mhp/PRRSV vaccination against this dual infection. Pigs dually infected with Mhp and PRRSV showed a combination of symptoms characteristic of each pathogen but no significant exacerbation of pathogenicity. Thus, the co-infected pigs displayed coughing and pneumonia typical of Mhp infection in addition to PRRSV-related hyperthermia and decrease in average daily gain (ADG). Hyperthermia was reduced in PRRSV vaccinated animals (single or combined vaccination), whereas ADG was restored in Mhp/PRRSV vaccinated pigs only. Regarding respiratory symptoms and lung lesions, no vaccine decreased coughing. However, all vaccines reduced the pneumonia score but more so in animals receiving the Mhp vaccine, whether single or combined. This vaccine also decreased the Mhp load in the respiratory tract. In conclusion, combined vaccination against both Mhp and PRRSV efficiently pooled the efficacy of each single PRRSV and Mhp vaccination and could be an interesting tool to control PRDC in European swine production.

We examined hematological parameters for a semifree-ranging population of mandrills to investigate the influence of age and sex, and to establish normative values for age-sex classes. We also investigated the influence of the reproductive cycle on hematological parameters in females and the influence of seasonality on both sexes. We examined hemoglobin concentration, platelet count, white cell count, red cell count, hematocrit, mean cell volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), and differential white cell counts, with a total of 459 observations. Red cell counts, hemoglobin, and hematocrit are significantly lower in females than in males, while female white cell counts are significantly higher. Platelet and white cell counts both decreased with age, while MCV and MCHC (males only) increased with age. Absolute lymphocyte counts also decreased with age. Female reproductive status had little effect on hematology, but melengestrol acetate contraceptive implants resulted in significant increases in hemoglobin, white cell count, red cell count, and hematocrit. Finally, lymphocyte counts increased significantly during the wet season in comparison with dry months, which may be related to increased parasite infection during the wet season. We compare our findings to those for other species, and discuss age-sex patterns in light of mandrill life history. Our results demonstrate the importance of including age-sex class, female reproductive status, and season in studies of hematology and will be useful in further studies of the colony.

The mandrill (Mandrillus sphinx) has been shown to be infected with an STLV-1 closely related to HTLV-1. Two distinct STLV-1 subtypes (D and F) infect wild mandrills with high overall prevalence (27.0%) but are different with respect to their phylogenetic relationship and parallel to the mandrills' geographic range. The clustering of these new STLV-1mnd sequences with HTLV-1 subtype D and F suggests first, past simian-to-human transmissions in Central Africa and second, that species barriers are easier to cross over than geographic barriers.

A recent serological survey of wild-born captive monkeys from Gabon, Central Africa, revealed that 1 of 20 Cercopithecus nictitans tested was infected with a new simian T cell lymphotropic virus type 1 (STLV-1). We investigated the molecular relationship between the STLV-1 strain present in this C. nictitans (CN01) and the other available HTLV/STLV strains. Phylogenetic analysis of the env (gp46 and gp21) region showed that the new STLV(nict) clusters with the HTLV-1/STLV-1 group and not with the other nictitans STLVs belonging to the STLV-3 group. Moreover, our new STLV(nict) is closely related to the molecular subtype D, which presently includes five HTLV-1 and three mandrill STLV-1 strains from Gabon and two from Cameroon. These data show that C. nictitans may be the natural carrier of two different molecular types of STLV, one related to STLV-3 and the other possibly one of the simian STLV type 1 counterparts of HTLV-1 subtype D.

African nonhuman primates are natural hosts for simian immunodeficiency viruses (SIVs). To date, SIV infections have been detected in 20 distinct species (24). SIVs were shown to cluster in six major, approximately equidistant lineages (17, 53). Human immunodeficiency virus type 1 (HIV-1) and HIV-2 belong to two of these clusters and emerged most likely following zoonotic transmissions of, respectively, SIVcpz from chimpanzees and SIVsm from sooty mangabeys (14, 16, 21). The remaining clusters are formed by SIVs isolated from African green monkeys (AGMs), Syke's monkeys, l'hoest monkeys, and colobus monkeys (4, 17, 20, 27, 39, 60). The phylogeny of many SIVs resembles that of their host species, suggesting a coevolution (1, 21, 39). In contrast to these, some viruses (SIVrcm, SIVagm.sab, SIVmnd-2, and SIVdrl) cluster in different lineages according to the genomic region analyzed (15, 22, 31, 55). These viruses most likely result from recombination events in monkeys dually infected by SIVs of two distinct lineages (15, 22, 31, 55). Such dual infections suppose the existence of cross-species transmissions of SIV in nature. It has indeed been shown that wild patas monkeys and baboons can acquire SIVagm (7, 32, 61). It remains unclear if these two latter species are infected with species-specific SIVs (54). This was also questioned for mandrills (Mandrillus sphinx). The first SIVmnd strain (GB1), now defined as SIVmnd-1, was isolated 13 years ago from a wild-born mandrill (59). This virus was the only representative of the SIVmnd lineage until two Cercopithecinae viruses, from l'hoest (Cercopithecus l'hoesti l'hoesti) and sun-tailed monkeys (Cercopithecus l'hoesti solatus) were shown to cluster in the same lineage as SIVmnd GB1 (4, 29). As the genome of SIVmnd GB1 had the organization of Cercopithecus SIVs and not that of Papionini SIVs, and because the habitat of mandrills and sun-tailed monkeys overlaps in Gabon, it was suggested that SIVmnd GB1 represents a virus cross-transmitted from sun-tailed monkeys to mandrills, and the lineage was renamed the l'hoest lineage (4, 5). It was subsequently demonstrated that SIVmnd GB1-related viruses are commonly present in wild adult mandrills, indicating that the virus is capable, at least today, of efficiently spreading between animals of this species (55). Mandrills infected with SIVmnd-1 are separated by the Ogooue River from mandrills infected with SIVmnd type 2 (55). This latter virus has a genomic organization distinct from those of SIVmnd GB1 and SIVlhoest and identical to that of SIVs of other Papio monkeys, such as SIVsm and SIVdrl (15, 55). It is unknown why SIV infections are generally nonpathogenic in African nonhuman primates. SIVmnd-2 infections in mandrills have not been associated with signs of AIDS. SIVmnd-1 infection, which apparently results from SIV transmission from C. l'hoesti to mandrills, is also considered to be asymptomatic, although a possible exception has been reported (44). SIVlhoest, which is genetically close to SIVmnd-1 and is also associated with asymptomatic infection in its natural host, appears to induce AIDS in macaques (29). In both HIV-1-infected humans and SIVmac-infected macaques, it was shown that early virus-host interactions are predictive of the outcome of infection. Predictive markers are in particular gag-specific T-helper responses and viral load levels in the post-acute phase of infection (36, 50). In macaques, the steady-state level of plasma viremia 5 to 6 weeks after exposure to the virus is an excellent predictor of the subsequent disease course (28, 35, 42, 63). RNA levels in plasma measured early in HIV-1 infection are also highly predictive of subsequent rates of disease progression (36, 37, 43). However, although this observation is broadly acknowledged and used as the main indication for treating HIV-1-infected patients early in the course of the disease (10), little is still known about the driving mechanism(s) directing this phenomenon. Studies of the early events during nonpathogenic infections in natural host species can help to elucidate such mechanisms. So far, studies during the early phase of infection in African nonhuman primates are limited (58). Studies in SIVagm.sab92018-infected AGMs have revealed for the first time an extensive replication during the acute and post-acute phases (18). Many naturally infected AGMs analyzed during the chronic phase also show continuously high levels of viral RNA in plasma (9, 23). Moreover, virus load in the blood and lymph nodes (LN) of mangabeys during chronic infection is at levels equivalent to that in macaques and humans progressing to AIDS, despite the lack of clinical signs of AIDS (49). The absence of AIDS in these monkeys therefore seems to be paradoxical in the presence of such a high viral load. However, it is not clear whether the high viral replication observed is a general feature of nonpathogenic infections in natural host species (3, 23). Moreover, the precise dynamics of CD4+ and CD8+ cells during primary infection have not been reported so far. Our primary objective for the present study was to investigate the acute and post-acute phases of SIVmnd-1 infection in mandrills. SIVmnd-1 is thought to represent the result of an ancient cross-species transmission in the wild (4, 6), and we investigated whether it would represent an intermediate model between the pathogenic and nonpathogenic models of lentiviral infections. We analyzed viral dynamics and corroborated the virological study with the analyses of CD4+- and CD8+-T-cell changes over time in the blood and LN.

HIV causes rapid CD4+ T cell depletion in the gut mucosa, resulting in immune deficiency and defects in the intestinal epithelial barrier. Breakdown in gut barrier integrity is linked to chronic inflammation and disease progression. However, the early effects of HIV on the gut epithelium, prior to the CD4+ T cell depletion, are not known. Further, the impact of early viral infection on mucosal responses to pathogenic and commensal microbes has not been investigated. We utilized the SIV model of AIDS to assess the earliest host-virus interactions and mechanisms of inflammation and dysfunction in the gut, prior to CD4+ T cell depletion. An intestinal loop model was used to interrogate the effects of SIV infection on gut mucosal immune sensing and response to pathogens and commensal bacteria in vivo. At 2.5 days post-SIV infection, low viral loads were detected in peripheral blood and gut mucosa without CD4+ T cell loss. However, immunohistological analysis revealed the disruption of the gut epithelium manifested by decreased expression and mislocalization of tight junction proteins. Correlating with epithelial disruption was a significant induction of IL-1β expression by Paneth cells, which were in close proximity to SIV-infected cells in the intestinal crypts. The IL-1β response preceded the induction of the antiviral interferon response. Despite the disruption of the gut epithelium, no aberrant responses to pathogenic or commensal bacteria were observed. In fact, inoculation of commensal Lactobacillus plantarum in intestinal loops led to rapid anti-inflammatory response and epithelial tight junction repair in SIV infected macaques. Thus, intestinal Paneth cells are the earliest responders to viral infection and induce gut inflammation through IL-1β signaling. Reversal of the IL-1β induced gut epithelial damage by Lactobacillus plantarum suggests synergistic host-commensal interactions during early viral infection and identify these mechanisms as potential targets for therapeutic intervention., Author Summary The loss of intestinal CD4+ T cells in chronic HIV infection is associated with impaired immune responses to pathogens, aberrant immune activation, and defects in the gut epithelial barrier. While much is known about the pathogenesis of HIV in chronic disease, less is known about the defects that occur prior to gut CD4+ T cell depletion and whether these defects alter host interactions with pathogenic and commensal bacteria. Using a non-human primate model of HIV infection, we examined the immune and structural changes in the gastrointestinal tract 2.5 days following SIV infection. Paneth cells, in immediate proximity of SIV infected immune cells, generated a robust IL-1β response. This IL-1β response correlated with defects in epithelial tight junctions and preceded the IFN-α response, which is characteristic of innate antiviral immune responses. Despite this inflammatory environment, we did not observe defects in mucosal immune responses to pathogenic or commensal bacteria. In fact, commensal bacteria were able to dampen the IL-1β response and ameliorate tight junction defects. Our study highlights the importance of the gut epithelium in HIV infection, not just as a target of pathogenesis but also the initiator of immune responses to viral infection, which can be strongly influenced by commensal bacteria.

International audience; BACKGROUND: The male genital tract is suspected to constitute a viral sanctuary as persistent HIV shedding is found in the semen of a subset of HIV-infected men receiving effective antiretroviral therapy (HAART). The origin of this persistent shedding is currently unknown. Phylogenetic studies indicated that HIV in semen from untreated men arises from local sources and/or passive diffusion from the blood. We previously demonstrated in human and macaque low levels and localized infection of several semen-producing organs by HIV/SIV. Using a macaque model, this study investigates the impact of short term HAART (2-4 weeks) initiated either during the asymptomatic chronic stage or 4 h post-intravenous inoculation of SIVmac251 on the infection of male genital organs. METHODOLOGY/PRINCIPAL FINDINGS: Short term HAART during the chronic stage decreased blood viral load. No major impact of HAART was observed on SIV DNA levels in male genital organs using a sensitive nested PCR assay. Using in situ hybridization, SIV RNA+ cells were detected in all male genital tract organs from untreated and treated animals with undetectable blood viral load following HAART. Infected CD68+ myeloid cells and CD3+ T lymphocytes were detected pre- and post-HAART. In contrast, short term HAART initiated 4 h post-SIV exposure led to a drastic decrease of the male genital tissues infection, although it failed to prevent systemic infection. In both cases, HAART tended to decrease the number of CD3+ T cells in the male organs. CONCLUSIONS: Our results indicate that the established infection of male genital organs is not greatly impacted by short term HAART, whereas the same treatment during pre-acute phase of the infection efficiently impairs viral dissemination to the male genital tract. Further investigations are now needed to determine whether infection of male genital organs is responsible for long term persistent HIV shedding in semen despite HAART.

International audience; BACKGROUND: The contribution of infected semen cells to sexual transmission of human immunodeficiency virus (HIV) is still debated. We addressed this issue in the model of experimental infection of macaques with simian immunodeficiency virus (SIV). METHODS: Frozen stocks of cells obtained from the spleen of macaques at the peak of SIVmac251 viremia were prepared. After being thawed and washed, cells were deposited at different concentrations in the vaginas of adult macaques treated with medroxyprogesterone acetate (Depo-Provera). To unravel mechanisms of infection, stock cells labeled with carboxyfluorescein diacetate succinimidyl ester (CFSE) were inoculated intravaginally. Follow-up testing of samples from the mucosa and different lymphoid tissues obtained 21 and 45 h later was performed by flow cytometry, immunohistochemical analysis, and in situ hybridization. RESULTS: Systemic and persistent infection was achieved after vaginal exposure of macaques to SIV-infected cells. The dose needed to infect 50% of females was 6.69 x 10(5)+/-2.08 x 10(5) viral DNA copies. At days 1 and 2 after exposure to cell-associated SIV labeled with CFSE, SIV-positive cells were detected in proximal and distal lymphoid tissues. CONCLUSIONS: Infection with SIV after exposure of vaginal and cervical mucosa to cell-associated virus represents a new mechanism of sexual transmission of HIV and SIV that may have significant impacts in the development of preventive approaches like microbicides.

Background HIV reservoirs are rapidly established after infection, and the effect of HAART initiated very early during acute infection on HIV reservoirs remains poorly documented, particularly in tissue known to actively replicate the virus. In this context, we used the model of experimental infection of macaques with pathogenic SIV to assess in different tissues: (i) the effect of a short term HAART initiated at different stages during acute infection on viral dissemination and replication, and (ii) the local concentration of antiviral drugs. Results Here, we show that early treatment with AZT/3TC/IDV initiated either within 4 hours after intravenous infection of macaques with SIVmac251 (as a post exposure prophylaxis) or before viremia peak (7 days post-infection [pi]), had a strong impact on SIV production and dissemination in all tissues but did not prevent infection. When treatment was initiated after the viremia peak (14 days pi) or during early chronic infection (150 days pi), significant viral replication persists in the peripheral lymph nodes and the spleen of treated macaques despite a strong effect of treatment on viremia and gut associated lymphoid tissues. In these animals, the level of virus persistence in tissues was inversely correlated with local concentrations of 3TC: high concentrations of 3TC were measured in the gut whereas low concentrations were observed in the secondary lymphoid tissues. IDV, like 3TC, showed much higher concentration in the colon than in the spleen. AZT concentration was below the quantification threshold in all tissues studied. Conclusions Our results suggest that limited antiviral drug diffusion in secondary lymphoid tissues may allow persistent viral replication in these tissues and could represent an obstacle to HIV prevention and eradication.

Background The time of infection is rarely known in human cases; thus, the effects of delaying the initiation of antiretroviral therapy (ART) on the peripheral viral load and the establishment of viral reservoirs are poorly understood. Methodology/Principal Findings Six groups of macaques, infected intravenously with SIVmac251, were given placebo or antiretroviral therapy to explore reservoir establishment; macaques were treated for 2 weeks, with treatment starting 4 hours, 7 or 14 days after infection. Viral replication and dissemination were measured in the gut (rectum), in the lung and in blood and lymphoid tissues (peripheral lymph nodes), by quantifying viral RNA, DNA and 2LTR circles. We used immunohistochemistry (CD4 and CD68) to assess the impact of these treatments on the relative amount of virus target cells in tissue. Treatment that was started 4 hours post-infection (pi) decreased viral replication and dissemination in blood and tissue samples, which were assessed on day 14 (RNA/DNA/2LTR circles). The virus remained detectable and lymphoid tissues were activated in LN and the gut in both placebo- and ART-treated animals. Viral RNA in plasma continued to be lower in macaques treated seven days after infection; however, this was not the case for viral DNA in peripheral blood mononuclear cells. There was a small but significant difference in RNA and DNA levels in tissues between placebo- and ART-treated animals on day 21. When started 14 days after infection, treatment resulted in a limited decrease in the plasma viral load. Conclusions Treatment that was started 4 hours after infection significantly reduced viral replication and dissemination. When started 7 days after infection, it was of slight virological benefit in peripheral blood and in tissues, and treatment was even less effective if started 14 days pi. These data favor starting ART no longer than one week after intravenous SIVmac251 exposure.

Background Extensive studies of primary infection are crucial to our understanding of the course of HIV disease. In SIV-infected macaques, a model closely mimicking HIV pathogenesis, we used a combination of three markers -- viral RNA, 2LTR circles and viral DNA -- to evaluate viral replication and dissemination simultaneously in blood, secondary lymphoid tissues, and the gut during primary and chronic infections. Subsequent viral compartmentalization in the main target cells of the virus in peripheral blood during the chronic phase of infection was evaluated by cell sorting and viral quantification with the three markers studied. Results The evolutions of viral RNA, 2LTR circles and DNA levels were correlated in a given tissue during primary and early chronic infection. The decrease in plasma viral load principally reflects a large decrease in viral replication in gut-associated lymphoid tissue (GALT), with viral RNA and DNA levels remaining stable in the spleen and peripheral lymph nodes. Later, during chronic infection, a progressive depletion of central memory CD4+ T cells from the peripheral blood was observed, accompanied by high levels of viral replication in the cells of this subtype. The virus was also found to replicate at this point in the infection in naive CD4+ T cells. Viral RNA was frequently detected in monocytes, but no SIV replication appeared to occur in these cells, as no viral DNA or 2LTR circles were detected. Conclusion We demonstrated the persistence of viral replication and dissemination, mostly in secondary lymphoid tissues, during primary and early chronic infection. During chronic infection, the central memory CD4+ T cells were the major site of viral replication in peripheral blood, but viral replication also occurred in naive CD4+ T cells. The role of monocytes seemed to be limited to carrying the virus as a cargo because there was an observed lack of replication in these cells. These data may have important implications for the targeting of HIV treatment to these diverse compartments.

The mandrill (Mandrillus sphinx) is naturally infected by two types of simian immunodeficiency virus (SIV): SIVmnd types 1 and 2. Both of these viruses cause long-term, non-progressive infections in their natural host despite high plasma viral loads. This study assessed the susceptibility of rhesus macaques to infection by these two types of SIVmnd and compared the virological and basic immunological characteristics of the resulting infections with those observed in natural infection in mandrills. Whilst both SIVmnd types induced similar levels of virus replication during acute infection in both mandrills and macaques, they produced a more pronounced CD4+ T-cell depletion in rhesus macaques that persisted longer during the initial stage of infection. Pro-inflammatory cytokine responses were also induced at higher levels in rhesus macaques early in the infection. During the chronic phase of infection in mandrills, which in this case was followed for up to 2 years after infection, high levels of chronic virus replication did not induce significant changes in CD4+ or CD8+ T-cell counts. In rhesus macaques, the overall chronic virus replication level was lower than in mandrills. At the end of the follow-up period, although the viral loads of SIVmnd-1 and SIVmnd-2 were relatively similar in rhesus macaques, only SIVmnd-1-infected rhesus macaques showed significant CD4+ T-cell depletion, in the context of higher levels of CD4+ and CD8+ T-cell activation, compared with SIVmnd-infected mandrills. The demonstration of the ability of both SIVmnd types to induce persistent infections in rhesus macaques calls for a careful assessment of the potential of these two viruses to emerge as new human pathogens.

Simian immunodeficiency virus (SIV) persistence in wild populations of African nonhuman primates (NHPs) may occur through horizontal and vertical transmission. However, the mechanism(s) and timing of the latter type of transmission have not been investigated to date. Here we present the first study of SIV transmissibility by breast-feeding in an African NHP host. Six mandrill dames were infected with plasma containing 300 50% tissue culture infective doses of SIVmnd-1 on the day after delivery. All female mandrills became infected, as demonstrated by both plasma viral loads (VLs) and anti-SIVmnd-1 seroconversion. Neither fever nor lymphadenopathy was observed. At the peak of SIVmnd-1 viral replication (days 7 to 10 postinoculation), plasma VLs were high (8 × 10 6 to 8 × 10 8 RNA copies/ml) and paralleled the high VLs in milk (4.7 × 10 4 to 5.6 × 10 5 RNA/ml). However, at the end of the breast-feeding period, after 6 months of follow-up, no sign of infection was observed for the offspring. Later on, during a 4-year follow-up examination, two of the offspring showed virological evidence of SIVmnd-1 infection. Both animals seroconverted at least 6 months after the interruption of lactation. In conclusion, despite extensive viral replication in mandrill mothers and high levels of free virus in milk, no SIVmnd-1 transmission was detectable at the time of breast-feeding or during the following months. Since we observed a markedly lower expression of CCR5 on the CD4 + T cells of young mandrills and African green monkeys than on those of adults, we propose that low levels of this viral coreceptor on CD4 + T cells may be involved in the lack of breast-feeding transmission in natural hosts of SIVs.

Background Previous epidemiological studies of rural human populations in Gabon reveal a high prevalence of human hepatitis A, B, C and D viruses. In order to investigate the prevalence of the blood-born hepatitis viruses in apes and monkeys living in the same area, we performed an epidemiological survey of HBV, HCV and HDV in wild-born non-human primates. Methods We tested 441 wild-born non-human primates from Gabon and Congo and 132 imported monkeys for the presence of serological markers of HBV, HCV and HDV infections. Results None of Cercopithecidae monkeys were reactive against HBV/HDV and HCV. In contrast, 29.2% of wild-born great apes (154 chimpanzees and 14 gorillas) were positive for HBV serological markers. Nine chimpanzees were in the replicative phase of HBV infection. None of these HBV infected chimpanzees exhibited symptoms or significant changes in serum clinical chemistry related to HBV infection. Conclusions The negativity to HCV-related viruses and the negativity of the Cercopithecidae species tested against HBV/HDV do not allow us to definitively rule out the presence of an animal counterpart of human hepatitis viruses in non-human primates.

Hepatitis B and C infections are endemic in human population in central Africa, particularly in Gabon. The aim of this study was to determine the prevalence of hepatitis B virus (HBV) and eventual occurrence of hepatitis C virus (HBC)-related strains in a variety of wild-born non-human primates living in Gabon and Congo. Plasma samples were screened for HBV and HCV markers. A non-invasive method of DNA extraction from faeces followed by specific HBV-DNA amplification was developed to study this infection in wild troops of chimpanzees and gorillas. No HCV infection in non-human primates, wild-born or captive, was detected among 596 samples tested. No HBV infection could be detected in samples tested and obtained from Cercopithecidae. In contrast, 14.7 and 42.2% of wild-born chimpanzees in Gabon and Congo were infected with HBV or had evidence of past HBV infection. At Centre International de Recherches Medicales (CIRMF) Primate Centre, 32.1% of chimpanzees and gorillas were HBV positive or had evidence of past infection. In the cases with past infection, 5.9% wild-born and 8.3% at CIRMF harboured HBV-DNA despite the presence of neutralizing HbsAb. Together with previous findings, we confirm the high HBV prevalence not only in humans but also in chimpanzees and gorillas in Gabon and Congo.