Transplacental transmission of BK virus in human.

The prevalance and distribution of BK virus antibody in women during pregnancy and the occurrence of transplacental transmission of BK virus was determined by measurement of IgM antibody in the serum. Sera were collected from 63 nonpregnant women, 71 women who had experienced spontaneous abortion, 80 in the first trimester of pregnancy and the same 80 at delivery. Umbilical cord blood was also taken at delivery. Hemagglutination inhibition (HI) tests for BK virus used the micromethod of Gardner. Results indicate that a significant level of HI antibody was present in 70% of sera from all 4 experimental groups. This showed that BK virus infection was not limited to cases of spontaneous abortion. Of the 80 pregnant mothers, 6 showed a 4-fold or greater HI antibody seroconversion to BK virus after delivery. Of these 6 seroconversion patients, sensitive antibody was detected in 3 umbilical cords. Umbilical cords of those without seroconversion had no sensitive antibody. As evidenced by 2-NE-sensitive antibody, BK virus infections were also recognized in 6 of 71 women who aborted, 4 of 80 in the first trimester of pregnancy and 2 collected after delivery. The 2-ME-sensitive antibody was not found in any of 63 samples from nonpregnant women. Data indicate that 2-ME-sensitive antibody was present only in sera of women during pregnancy and after abortion. It may be possible that BK virus persists in a latent form in many healthy women and becomes activated during pregnancy.     

寨卡病毒与性传播

寨卡病毒是蚊源性虫媒病毒,归属于黄病毒科黄病毒属。1947年在乌干达寨卡森林的一头哨猴(恒河猴)中首次分离到。上世纪60年代在亚洲和非洲报告有散发性病例。2007年,在密克罗尼西亚雅浦岛发生以发热与皮疹为特征的第一次大流行;2013年10月在法属波利尼西亚发生了南太平洋最大的寨卡病毒爆发流行;在2015年引入巴西的寨卡病毒引起爆发。迄今,巴西已有150万人感染,并扩展到世界上30多个国家,大多数在南美洲。由于在巴西不正常地密集出现新生儿小头畸形,而母亲在孕期曾感染过寨卡病毒,因此世界卫生组织宣布世界范围内流行的寨卡病毒是国际关注的突发公共卫生事件。寨卡病毒感染是酷似登革热的、自限性的发热、皮疹、关节痛综合征,我国称寨卡病毒病。大多数病例是轻症,主要症状是皮疹、发热、关节痛、肌痛、头痛和结膜炎。寨卡病毒自然传播中的媒介为伊蚊,但也存在非生物媒介传播的危险。曾从血清中分离到寨卡病毒,并证实性交传播。最近有更多的由性传播的病例报告。寨卡病毒由病毒携带的男性经性行为传染给女方。如果最近刚从寨卡病毒流行区来的男性,在性生活中应使用安全套;如果女方已经怀孕,最好是放弃性接触,以保护胎儿。     

Transplacental transmission of a leukemogenic murine leukemia virus.

Recombinant inbred BXH-2 mice spontaneously produce a B-tropic murine leukemia virus (MuLV) beginning early in life and have a high incidence of spontaneous myeloid leukemia. These traits are not characteristic of the progenitor strains (C57BL/6J and C3H/HeJ) or of 11 other recombinant inbred BXH strains. Genetic analysis has shown that the virus is not transmitted through the germ line, suggesting that the virus is passed from one generation to the next by horizontal transmission. An additional ecotropic proviral locus was detected in some mice of this strain after several generations of inbreeding. We show that BXH ecotropic virus was transmitted to other strains when fostered on viremic BXH-2 mice and that these mice go on to develop tumors of hematopoietic origin. Our earlier finding that virus is expressed early in gestation suggested that the ecotropic MuLV is also transmitted in utero. In order to determine the stage at which the ecotropic MuLV is transmitted in utero, preimplantation stage embryos were transferred to the uteri of recipient ecotropic virus-negative mice. These mice were found to be negative for the presence of the ecotropic MuLV, suggesting that transplacental transmission of the ecotropic virus readily occurs in BXH-2 mice. Although other viruses, including human lentiviruses, are transmitted across the placental barrier, transplacental transmission of MuLV is a rare event. Thus, the BXH-2 mouse strain may contribute to our understanding of the mechanism of transplacental transmission and pathogenesis and offers a potential new model for use in drug therapy of exogenously transmitted viruses related to lentiviruses.     

Interactions between human immunodeficiency virus type 1 and vaccinia virus in human lymphoid tissue ex vivo

Vaccinia virus (VACV) has been attracting attention recently not only as a vector for various vaccines but also as an immunization tool against smallpox because of its potential use as a bioterrorism agent. It has become evident that in spite of a long history of studies of VACV, its tissue pathogenesis remains to be fully understood. Here, we investigated the pathogenesis of VACV and its interactions with human immunodeficiency virus type 1 (HIV-1) in the context of human lymphoid tissues. We found that ex vivo-cultured tonsillar tissue supports productive infection by the New York City Board of Health strain, the VACV strain of the Dryvax vaccine. VACV readily infected both T and non-T (B) lymphocytes and depleted cells of both of these subsets equally over a 12-day period postinfection. Among T lymphocytes, CD8(+) cells are preferentially depleted in accordance with their preferential infection: the probability that a CD8(+) T cell will be productively infected is almost six times higher than for a CD4(+) T cell. T cells expressing CCR5 and the activation markers CD25, CD38, and HLA-DR are other major targets for infection by VACV in lymphoid tissue. As a consequence, VACV predominantly inhibits the replication of the R5(SF162) phenotype of HIV-1 in coinfected tissues, as R5-tropic HIV-1 requires activated CCR5(+) CD4(+) cells for productive infection. Human lymphoid tissue infected ex vivo by VACV can be used to investigate interactions of VACV with other viruses, in particular HIV-1, and to evaluate various VACV vectors for the purpose of recombinant vaccine development.     

Wolbachia strain wAlbA blocks Zika virus transmission in Aedes aegypti

Transinfections of the maternally transmitted endosymbiont Wolbachia pipientis can reduce RNA virus replication and prevent transmission by Aedes aegypti, and also have the capacity to invade wild-type populations, potentially reaching and maintaining high infection frequencies. Levels of virus transmission blocking are positively correlated with Wolbachia intracellular density. Despite reaching high densities in Ae. aegypti, transinfections of wAlbA, a strain native to Aedes albopictus, showed no blocking of Semliki Forest Virus in previous intrathoracic injection challenges. To further characterize wAlbA blocking in Ae. aegypti, adult females were intrathoracically challenged with Zika (ZIKV) and dengue viruses, and then fed a ZIKV-containing bloodmeal. No blocking was observed with either virus when challenged by intrathoracic injection. However, when ZIKV was delivered orally, wAlbA-infected females showed a significant reduction in viral replication and dissemination compared with uninfected controls, as well as a complete absence of virus in saliva. Although other Wolbachia strains have been shown to cause more robust viral blocking in Ae. aegypti, these findings demonstrate that, in principle, wAlbA could be used to reduce virus transmission in this species. Moreover, the results highlight the potential for underestimation of the strength of virus-blocking when based on intrathoracic injection compared with more natural oral challenges.     

The effect of sexual transmission on Zika virus dynamics

Journal of Mathematical Biology - Zika virus is a human disease that may lead to neurological disorders in affected individuals, and may be transmitted vectorially (by mosquitoes) or sexually. A...     

Mathematical model for Zika virus dynamics with sexual transmission route

Zika virus is a flavivirus transmitted to humans primarily through the bite of infected Aedes mosquitoes. In addition to vector-borne spread, however, the virus can also be transmitted through sexual contact. In this paper, we formulate and analyze a new system of ordinary differential equations which incorporates both vector and sexual transmission routes. Theoretical analysis of this model when there is no disease induced mortality shows that the disease-free equilibrium is locally and globally asymptotically stable whenever the associated reproduction number is less than unity and unstable otherwise. However, when we extend this same model to include Zika induced mortality, which have been documented in Latin America, we find that the model exhibits a backward bifurcation. Specifically, a stable disease-free equilibrium co-exists with a stable endemic equilibrium when the associated reproduction number is less than unity. To further explore model predictions, we use numerical simulations to assess the importance of sexual transmission to disease dynamics. This analysis shows that risky behavior involving multiple sexual partners, particularly among male populations, substantially increases the number of infected individuals in the population, contributing significantly to the disease burden in the community.     

Nef enhances human immunodeficiency virus replication and responsiveness to interleukin-2 in human lymphoid tissue ex vivo

The nef gene is important for the pathogenicity associated with simian immunodeficiency virus infection in rhesus monkeys and with human immunodeficiency virus type 1 (HIV-1) infection in humans. The mechanisms by which nef contributes to pathogenesis in vivo remain unclear. We investigated the contribution of nef to HIV-1 replication in human lymphoid tissue ex vivo by studying infection with parental HIV-1 strain NL4-3 and with a nef mutant (DeltanefNL4-3). In human tonsillar histocultures, NL4-3 replicated to higher levels than DeltanefNL4-3 did. Increased virus production with NL4-3 infection was associated with increased numbers of productively infected cells and greater loss of CD4(+) T cells over time. While the numbers of productively infected T cells were increased in the presence of nef, the levels of viral expression and production per infected T cell were similar whether the nef gene was present or not. Exogenous interleukin-2 (IL-2) increased HIV-1 production in NL4-3-infected tissue in a dose-dependent manner. In contrast, DeltanefNL4-3 production was enhanced only marginally by IL-2. Thus, Nef can facilitate HIV-1 replication in human lymphoid tissue ex vivo by increasing the numbers of productively infected cells and by increasing the responsiveness to IL-2 stimulation.     

Noninvasive determination of perfused artery dimensions ex vivo using a pressure-diameter relationship

Based on the decisive effects of the hemodynamic and mechanical environments on the development and remodeling of arteries in vivo, several groups have cultured tissue-engineered vessels and excised vessels in various mechanically active perfusion systems. To facilitate the interpretation and design of such studies, accurate estimates of the applied forces and resulting stresses are required, which in turn require an accurate estimate of vessel dimensions. The measured pressure drop along the length of the vessel could be used to calculate the average inner diameter, but practical considerations, including the modest accuracy of many pressure transducers, limit this approach. Using nine porcine arteries harvested from pigs weighing between 25 and 100 kg, we show that when real-time measurements of the pressure drop and the outer diameter during a vasoactive event are fit to a theoretical model, offset errors in the pressure measurement can be compensated for and estimates of vessel wall transverse area with an average error of 4.1% (not exceeding 8.3%) are achieved.     

Fluorimetric characterisation of metabolic activity of ex vivo perfused pig hearts.

Autofluorescence of tissues and organs is an indicator of the physiological state of cells. The aim of the study was to investigate whether fluorimetric determination of the redox state of the ex vivo perfused pig heart can provide fast online detection of progressive changes in heart muscle tissue. Measurements on six organs perfused in a four-chamber working heart model were performed using a spectroscopic method exploiting the specific and different fluorescence lifetimes of intrinsic fluorophores such as NADH and flavins and providing a means of internal signal referencing. It was shown that the redox potential of heart muscle tissue can be assessed by fluorescence measurement. In the steady-state phase of the beating heart, spectroscopic measurements revealed a change in redox state from an initial constant level to a continuous decrease, accompanied by a decrease in heart performance and indications of changes in electrolyte equilibrium (K(+) concentration). At the same time, troponin I levels in the perfusate increased. The results indicate that fluorimetric determination of heart muscle metabolic activity yields reliable information about the functional status of the ex vivo heart and may be advantageous for the optimisation of ex vivo organ models.     

Radioprotective effects of ATP in human blood ex vivo

Damage to healthy tissue is a major limitation of radiotherapy treatment of cancer patients, leading to several side effects and complications. Radiation-induced release of pro-inflammatory cytokines is thought to be partially responsible for the radiation-associated complications. The aim of the present study was to investigate the protective effects of extracellular ATP on markers of oxidative stress, radiation-induced inflammation and DNA damage in irradiated blood ex vivo. ATP inhibited radiation-induced TNF-α release and increased IL-10 release. The inhibitory effect of ATP on TNF- α release was completely reversed by adenosine 5′-O-thiomonophosphate, indicating a P2Y₁₁ mediated effect. Furthermore, ATP attenuated radiation-induced DNA damage immediate, 3 and 6 h after irradiation. Our study indicates that ATP administration alleviates radiation-toxicity to blood cells, mainly by inhibiting radiation-induced inflammation and DNA damage.     

Differential pathogenesis of primary CCR5-using human immunodeficiency virus type 1 isolates in ex vivo human lymphoid tissue

In the course of human immunodeficiency virus (HIV) disease, CCR5-utilizing HIV type 1 (HIV-1) variants (R5), which typically transmit infection and dominate its early stages, persist in approximately half of the infected individuals (nonswitch virus patients), while in the other half (switch virus patients), viruses using CXCR4 (X4 or R5X4) emerge, leading to rapid disease progression. Here, we used a system of ex vivo tonsillar tissue to compare the pathogeneses of sequential primary R5 HIV-1 isolates from patients in these two categories. The absolute replicative capacities of HIV-1 isolates seemed to be controlled by tissue factors. In contrast, the replication level hierarchy among sequential isolates and the levels of CCR5(+) CD4(+) T-cell depletion caused by the R5 isolates seemed to be controlled by viral factors. R5 viruses isolated from nonswitch virus patients depleted more target cells than R5 viruses isolated from switch virus patients. The high depletion of CCR5(+) cells by HIV-1 isolates from nonswitch virus patients may explain the steady decline of CD4(+) T cells in patients with continuous dominance of R5 HIV-1. The level of R5 pathogenicity, as measured in ex vivo lymphoid tissue, may have a predictive value reflecting whether, in an infected individual, X4 HIV-1 will eventually dominate.     

Effective ex vivo neutralization of human immunodeficiency virus type 1 in plasma by recombinant immunoglobulin molecules.

We tested the ability of human monoclonal antibodies (immunoglobulin G1b12 [IgG1b12] and 19b) and CD4-based molecules (CD4-IgG2 and soluble CD4 [sCD4]) to neutralize human immunodeficiency virus type 1 directly from the plasma of seropositive donors in an ex vivo neutralization assay. IgG1b12 and CD4-IgG2, at concentrations from 1 to 25 micrograms/ml, were found to be effective at reducing the HIV-1 titer in most plasma samples. When viruses recovered from plasma samples were expanded to produce virus stocks, no correlation between the neutralization sensitivities to IgG1b12 and CD4-IgG2 of the in vitro passaged stocks and those of the ex vivo neutralizations performed directly on the plasma was observed. These differences could be due to changes in neutralization sensitivity that occur after one passage of the virus in vitro, or they could be related to the presence of complement or antibodies in the plasma. Furthermore, differences in expression of adhesion molecules on plasma-derived and phytohemagglutinin-activated peripheral blood mononuclear cell-derived viruses could be involved. These studies suggest that IgG1b12 and CD4-IgG2 have broad and potent neutralizing activity in both in vitro and ex vivo neutralization assays and should be considered for use as potential immunoprophylactic or therapeutic agents.     

寨卡病毒研究进展

寨卡病毒(zikavirus,ZIKV)发现距今已有70多年。早期的患者临床症状较轻,通常为自限性疾病。近年来,由于基因突变使ZIKV致病力逐渐增强,导致严重的神经系统并发症,引起了人们普遍关注。目前,全球尚无针对性的疫苗和药物,ZIKV的暴发、流行已经成为全球公共卫生问题。为了有效防控ZIKV感染,许多国家和地区加快了对ZIKV的研究,并取得了一定的成果,现就ZIKV的生物学特征、流行特点、致病机制及防控措施等作一概述。     

Compromising human skin in vivo and ex vivo to study skin barrier repair

Ex vivo regenerated stratum corneum (SC) after tape-stripping can be used as a model to study the barrier function of compromised skin. Yet, details about how close the regenerated SC model mimics the lipid properties (e.g. lipid composition and lipid ordering) of the in vivo situation are not known. Here, we examined using a comprehensive ceramide analysis whether human ex vivo regenerated SC showed similar lipid properties as human in vivo regenerated SC. Both in vivo and ex vivo regenerated SC had an altered ceramide subclass composition, with increased percentages of sphingosine-based subclass and decreased percentages of phytosphingosine-based subclass ceramides, a reduced mean ceramide chain length, and a higher percentage of unsaturated ceramides. Overall, regenerated SC ex vivo showed more pronounced but similar changes compared to the in vivo response. One of the purposes of these models is to use them to mimic compromised skin of inflammatory skin diseases. The altered lipid properties in regenerated SC were comparable to those observed in several inflammatory skin diseases, which makes them a valuable model for the barrier properties in inflammatory skin diseases.     

Pathogenic effects of human herpesvirus 6 in human lymphoid tissue ex vivo

Human herpesvirus 6 (HHV-6) is a potentially immunosuppressive agent that has been suggested to act as a cofactor in the progression of human immunodeficiency virus disease. However, the lack of suitable experimental models has hampered the elucidation of the mechanisms of HHV-6-mediated immune suppression. Here, we used ex vivo lymphoid tissue to investigate the cellular tropism and pathogenic mechanisms of HHV-6. Viral strains belonging to both HHV-6 subgroups (A and B) were able to productively infect human tonsil tissue fragments in the absence of exogenous stimulation. The majority of viral antigen-expressing cells were CD4(+) T lymphocytes expressing a nonnaive phenotype, while CD8(+) T cells were efficiently infected only with HHV-6A. Accordingly, HHV-6A infection resulted in the depletion of both CD4(+) and CD8(+) T cells, whereas in HHV-6B-infected tissue CD4(+) T cells were predominantly depleted. The expression of different cellular antigens was dramatically altered in HHV-6-infected tissues: whereas CD4 was upregulated, both CD46, which serves as a cellular receptor for HHV-6, and CD3 were downmodulated. However, CD3 downmodulation was restricted to infected cells, while the loss of CD46 expression was generalized. Moreover, HHV-6 infection markedly enhanced the production of the CC chemokine RANTES, whereas other cytokines and chemokines were only marginally affected. These results provide the first evidence, in a physiologically relevant study model, that HHV-6 can severely affect the physiology of secondary lymphoid organs through direct infection of T lymphocytes and modulation of key membrane receptors and chemokines.