Do signs of abdominal wall injury on computed tomography predict intra-abdominal injury in trauma patients with a seatbelt sign?

BACKGROUND: A seatbelt sign in patients with blunt abdominal injury is associated with both abdominal wall and intra-abdominal injuries. This study aimed to assess the association between signs of abdominal wall injury on computed tomography (CT) and rates of intra-abdominal injury in patients with a blunt abdominal injury and a clinical seatbelt sign. METHODS: This study includes hemodynamically stable trauma patients with blunt abdominal injury and a clinical seatbelt sign who were hospitalized in two regional trauma centers in Israel, during 2014-2019. All data were collected via the medical center's trauma registry in both centers. RESULTS: We identified 123 stable blunt abdominal trauma patients with a seatbelt sign, of which 101 (82.1%) and 22 (17.9%) had a low-grade and high-grade abdominal wall injury according to CT findings, respectively. Laparotomy rates were significantly higher in patients with signs of high-grade abdominal wall injury (p<0.0001). No differences in the timing of laparotomy between low and high-grade injuries were found. CONCLUSIONS: In stable patients with blunt abdominal trauma and a clinical seatbelt sign, the severity of abdominal wall injury, as represented by CT findings, may predict a need for surgical treatment.

Thoracic vertebrae fracture: Is it an indicator of abdominal injury?

PURPOSE: Traumatic vertebral fracture accounts for 10-15% of trauma related admissions. While the correlation between lumbar vertebral fractures and abdominal injuries is well established, the relationship between thoracic vertebral fractures (TVF) and abdominal injuries is comparatively less well elucidated. Using a large national trauma database, we aimed to examine the incidence and severity of associated abdominal injuries in blunt trauma patients suffering from TVF. METHODS: A retrospective cohort study using the Israeli National Trauma Registry was conducted. Patients with thoracic vertebrae spine fractures following blunt mechanisms of trauma between 1997 and 2018 were examined, comparing the incidence and severity of associated intraabdominal organs injuries with and without TVF. Demographics and outcomes between the two cohorts were compared. RESULTS: From 362,924 blunt trauma patients, 4967 (1.37%) had isolated TVF. Mean age was 49.8 years and 61.9% were males. The most common mechanism of injury was fall following by MVC. The patients with TVF had significantly higher rates of increased ISS score (ISS > 16, 28.45% vs. 10.42%, p < 0.001) and higher mortality rate (3.5% vs. 2%, p < 0.0001). Patients with TVF had 2-3 times more intraabdominal organ injuries (p < 0.001). The most commonly injured organ was spleen (3.28%); followed by liver (2.64%) and kidney (1.47%). An analysis of non-isolated thoracic spine fractures showed same distribution in age, ISS, mechanisms, patterns of intra-abdominal injury, mortality rate and laparotomy rate. CONCLUSION: Clinicians should have an elevated suspicion for intra-abdominal injuries when a thoracic spine fracture is identified, which may necessitate further evaluation.

Sequential immunization of macaques with two differentially attenuated vaccines induced long-term virus-specific immune responses and conferred protection against AIDS caused by heterologous simian human immunodeficiency Virus (SHIV(89.6)P).

Four rhesus macaques were sequentially immunized with live vaccines DeltavpuDeltanefSHIV-4 (vaccine-I) and Deltavpu SHIV(PPC) (vaccine-II). The vaccine viruses did not replicate productively in the peripheral blood mononuclear cells (PBMCs) of the vaccinated animals. All four animals developed binding antibodies against both the vaccine-I and -II envelope glycoproteins but neutralizing antibodies only against vaccine-I. They developed vaccine virus-specific CTLs that also recognized homologous as well as heterologous pathogenic SHIVs. Thirty weeks after the last immunization, the vaccinated animals and three unvaccinated control animals were challenged iv with a highly virulent heterologous SHIV(89.6)P. As expected, the three unvaccinated control animals developed large numbers of infectious PBMCs, high plasma viremia, and precipitous loss of CD4(+) T cells. Two controls did not develop any immune response and succumbed to AIDS in about 6 months. The third control animal developed neutralizing antibodies and had a more chronic disease course, but eventually succumbed to AIDS-related complications 81 weeks after inoculation. The four vaccinated animals became infected with challenge virus as indicated by the presence of challenge virus-specific DNA in the PBMCs and RNA in plasma. However, virus in these animals replicated approximately 200- to 60,000-fold less efficiently than in control animals and eventually, plasma viral RNA became undetectable in three of the four vaccinates. The animals maintained normal CD4(+) T-cell levels throughout the observation period of 85 weeks after a transient drop at Week 3 postchallenge. They also maintained CTL responses throughout the observation period. These studies thus showed that the graded immunization schedule resulted in a safe and highly effective long-lasting immune response that was associated with protection against AIDS by highly pathogenic heterologous SHIV(89.6)P.

Determination of the prime electrostatic endothelial cell transplantation procedure for e-PTFE vascular prostheses.

The purpose of this study was to evaluate the extent of cellular adhesion (density and morphological maturation), cellular membrane damage, and cellular viability after an electrostatic transplantation of human umbilical vein endothelial cells (HUVECs) onto 6-cm segments of 4-mm I.D. e-PTFE (GORE-TEX) vascular prostheses using a prototype electrostatic endothelial cell transplantation device (EECTD). The electrostatic transplantation parameters evaluated were the apparatus-applied voltage and transplantation time. By our definition, the combination of applied voltage and transplantation time that met the a priori criteria of: 1) maximum transplanted cellular viability, 2) maximum transplantation density, 3) maximum morphological maturation (degree of cellular flattening), and 4) minimal cellular membrane damage would be the prime transplantation procedure. The results of the experimentation indicated that the prime conditions for HUVEC transplantation were obtained when +1.0 V was applied for a transplantation time of 16 min. These conditions achieved an average viable graft surface coverage of 97.4+/-1.6% with an average transplantation density of 73,540+/-8.514 HUVECs/cm2. Furthermore, the transplanted HUVECs were morphologically mature (flattened) with minimal apparent cellular membrane damage (lysis or pitting). The overall clinical significance of this study is that viable endothelial cell transplantation to synthetic vascular grafts can be accomplished at high cellular densities and morphological maturation in 16 min using the EECTD. With the promising in vitro transplantation results, the next logical investigations will include additional in vitro evaluations (cellular retention upon shear stress exposure and biochemical assays) followed by in vivo evaluations to examine thromboresistance and influence on intimal/anastomotic hyperplasia.

Evaluation of immune responses induced by HIV-1 gp120 in rhesus macaques: effect of vaccination on challenge with pathogenic strains of homologous and heterologous simian human immunodeficiency viruses.

The simian human immunodeficiency virus (SHIV) macaque model of AIDS has provided a very useful system for evaluation of envelope-based candidate vaccines against HIV-1. Eight rhesus macaques were immunized with monomeric recombinant gp120 of HIV-1(LAI) (rgp120) and used to evaluate whether this vaccine conferred protection against challenge with pathogenic SHIVs (SHIV(KU-2) and SHIV(89.6)P). The vaccinated macaques developed high titers of antibodies against rgp120 that reacted efficiently with the envelope proteins of homologous SHIV (SHIV(KU-2)) and poorly with the SHIV(89.6)P envelope, a heterologous strain of SHIV. This vaccine also induced neutralizing antibodies but only against SHIV(KU-2). Vaccine-induced antibodies were of high avidity and predominantly against linear epitopes on the protein. Vaccinated macaques developed gp120-specific T-helper cells but no consistent cytotoxic T lymphocytes. However, cellular immune responses were short-lived in all eight vaccinates. At week 22 postimmunization, four vaccinates were challenged with SHIV(KU-2) and the other four with SHIV(89.6)P. Four unvaccinated control macaques were also infected: two with SHIV(KU-2) and two with SHIV(89.6)P. Vaccinated macaques generally showed anamnestic antibody and T-helper cell responses. However, T-helper responses were again short-lived. Upon challenge, the level of productive virus replication was indistinguishable between vaccine and control groups, suggesting that rgp120 did not confer protection against virus replication when animals were challenged with homologous or heterologous SHIV viruses.

Use of herpesvirus saimiri-immortalized macaque CD4(+) T cell clones as stimulators and targets for assessment of CTL responses in macaque/AIDS models.

Herpesvirus saimiri (HVS), a nonhuman primate gamma herpes virus, was used to immortalize pig-tailed macaque CD4(+) T lymphocytes. The HVS-immortalized T cell lines were used to develop CD4(+) T cell clones from two animals. Three CD4(+) T cell clones were further characterized for the expression of cell surface markers. All expressed CD2, CD4, CD58, CD69 and CD80 and therefore resembled activated T cells. These clones required exogenous IL-2 for efficient growth and were found to be highly susceptible to infection by the challenge virus, Chimeric simian/human immunodeficiency virus (SHIV(KU-1)). They could also be productively infected not only by the quasispecies of the challenge virus (SHIV(KU-1/PDJ) and SHIV(KU-1/PNA), isolated from macaque PDj and PNa, respectively) but also by a different chimeric simian/human immunodeficiency virus (SHIV(89.6P)) and simian immunodeficiency virus (SIV(MAC239)). The virus-infected CD4(+) T cell clones were also used as stimulators for generation of CTL effectors. These effectors exhibited excellent virus-specific lysis in chromium-release assays when syngenic SHIV(KU-1) infected autologous CD4(+) T cell clones were used as targets. The target cell lysis was virus specific, as uninfected control cells showed no or minimal lysis.

Growth changes in internal and craniofacial flexion measurements.

Growth changes in both internal and craniofacial flexion angles are presented for Pan troglodytes, Gorilla gorilla, and modern humans. The internal flexion angle (IFA) was measured from lateral radiographs, and the craniofacial flexion angle (CFA) was calculated from coordinate data. Stage of dental development is used as a baseline for examination of growth changes and nonparametric correlations between flexion angles and dental development stage are tested for significance. In Gorilla, the IFA increases during growth. The IFA is relatively stable in Pan and modern humans. Pan and Gorilla display an increase in the CFA. However, this angle decreases during growth in modern humans. Flexion angles were derived from coordinate data collected for several early hominid crania. Measurements for two robust australopithecine crania indicate strong internal flexion. It has been suggested that cerebellar expansion in this group may relate to derived features of the posterior cranial base. In general, australopithecine crania exhibit craniofacial flexion intermediate between great apes and modern humans. The "archaic" Homo sapiens specimen from Kabwe is most similar to modern humans.

Growth changes in measurements of upper facial positioning.

Growth changes in the position of the midline upper face are examined for samples of Pan troglodytes, Gorilla gorilla, and modern humans. Horizontal and vertical distances between nasion and the anterior end of the cribriform plate are plotted against stage of dental development. Kendall's nonparametric correlations between facial positioning and stage of dental development are tested for significance. In African apes, the upper face becomes more projecting and positioned higher relative to the anterior cranial base. The extent of this horizontal and vertical separation reflects primarily facial size. In modern humans, the upper face becomes more projecting but is relatively stable in its vertical position. Comparison of Pan and modern human crania in the youngest dental age category indicates that the upper face of modern humans is positioned lower early in postnatal life. The position of the upper face (glabella) relative to the anterior and posterior cranial base is presented for several fossil hominid crania. The fossil crania are similar to Pan and modern humans in facial projection relative to the anterior cranial base. However, glabella is positioned low in the fossil crania. Total facial projection (relative to hormion) for Sts 5 is similar to the mean for Gorilla. Fossil Homo and robust australopithecine crania display very projecting upper faces. We suggest that the upper face of Homo is projecting due to the length of the anterior cranial fossa, while robust australopithecines possess a thick frontal bone.

Detection of breast lesions by holographic interferometry.

The holographic interferometry (HI) technique commonly used for nondestructive testing of laminate materials was applied to create fringe contour distortion near the site of indwelling breast lesions. For this medical imaging application, the HI technique was successful in demonstrating abnormal mechanical properties of living tissue. Adequate density and contrast of fringes, crucial factors necessary for analysis of surface deformation of an object, can be made only with an appropriate stressing method. We have applied vibration and mild pressure to the surface of female breasts for the purpose of detecting localized densities and mass alterations of the tissue, which may be indicative of an abnormality of that tissue. Even though each stressing method had both positive and negative aspects, pneumatic pressure was adopted for the present study because it was more suitable for a noninvasive and noncontact breast examination. We also developed a computer based holographic imaging system to precisely control the stressing phase for the pressure and laser triggering so the resultant holograms had manageable fringe density and repeatability. © 1999 Society of Photo-Optical Instrumentation Engineers.

Oral immunization of macaques with attenuated vaccine virus induces protection against vaginally transmitted AIDS.

The chimeric simian-human immunodeficiency virus SHIVKU-1, bearing the envelope of human immunodeficiency virus type 1 (HIV-1), causes fulminant infection with subtotal loss of CD4(+) T cells followed by development of AIDS in intravaginally inoculated macaques and thus provides a highly relevant model of sexually transmitted disease caused by HIV-1 in human beings. Previous studies using this SHIV model had shown that the vpu and nef genes were important in pathogenesis of the infection, and so we deleted portions of these genes to create two vaccines, DeltavpuDeltanefSHIV-4 (vaccine 1) and DeltavpuSHIVPPc (vaccine 2). Six adult macaques were immunized subcutaneously with vaccine 1, and six were immunized orally with vaccine 2. Both viruses caused infection in all inoculated animals, but whereas vaccine 1 virus caused only a nonproductive type of infection, vaccine 2 virus replicated productively but transiently for a 6- to 10-week period. Both groups were challenged 6 to 7 months later with pathogenic SHIVKU-1 by the intravaginal route. All four unvaccinated controls developed low CD4(+) T-cell counts (<200/microliter) and AIDS. The 12 vaccinated animals all became infected with SHIVKU-1, and two in group 1 developed a persistent productive infection followed by development of AIDS in one. The other 10 have maintained almost complete control over virus replication even though spliced viral RNA was detected in lymph nodes. This suppression of virus replication correlated with robust antiviral cell-mediated immune responses. This is the first demonstration of protection against virulent SHIV administered by the intravaginal route. This study supports the concept that sexually transmitted HIV disease can be prevented by parenteral or oral immunization.

Chronology of genetic changes in the vpu, env, and Nef genes of chimeric simian-human immunodeficiency virus (strain HXB2) during acquisition of virulence for pig-tailed macaques.

Recently, we developed a highly pathogenic variant of simian-human immunodeficiency virus, SHIV-4 (containing the tat, rev, vpu, and env of the HXB2 strain of HIV-1 in a genetic background of SIVmac239), through a series of four bone marrow-bone marrow passages-first in rhesus monkeys and then in pig-tailed macaques [Joag et al. (1996) J. Virol. 70, 3189-3197]. Inoculation of pig-tailed macaques with this pathogenic virus (SHIVKU-1) causes subtotal elimination of CD4(+) T cells and fatal opportunistic infections, usually within 6 months. Genetic characterization of SHIVKU-1 showed that it has a functional vpu gene (the first codon is ATG vs ACG for the vpu of SHIV-4) and several amino acid substitutions in Env and nef [Stephens et al. (1997) Virology 231, 313-321]. Two pig-tailed macaques, PPc and PQc, were the first to develop a severe loss of CD4(+) T cells and the acquired immune deficiency syndrome and were euthanized at 26 and 105 weeks, respectively. In this report, we analyzed the changes that occurred in the vpu, nef, and env (gp120) genes of the virus used to inoculate macaques PPc and PQc and established the chronology of changes that occurred in these viral genes as these two animals lost their CD4(+) T cells and progressed to develop acquired immune deficiency syndrome. Compared with SHIV-4, the virus used to inoculate macaques PPc and PQc had 0, 3, and 0 consensus amino acid changes in the Vpu, gp120, and Nef, respectively. An analysis of the viral sequences amplified from peripheral blood mononuclear cells samples taken at various times after inoculation of PPc revealed that the vpu had not reverted to an open reading frame (closed vpu, ACG) at 4 weeks after inoculation, but by 16 weeks vpu had reverted to an open reading frame (open vpu, ATG). Macaque PQc, which had a longer course of disease, had a closed vpu at 4 and 16 weeks, but by 28 weeks, both closed and open vpu were detected. From 39 to 105 weeks, only an open vpu was detected. In both macaques, the reversion to an open vpu correlated well with the second phase (major) of CD4(+) T cell loss. An analysis of the nef and env sequences isolated from the same times after inoculation revealed an association between the reversion of vpu to an open reading frame and the accumulation of increased numbers of consensus changes in these two viral proteins. These data suggest that the concomitant reversion of vpu to an open reading frame along with increased substitutions in Nef and gp120 were important genetic changes in the viral genome that were responsible for the increased and highly efficient rate of replication of the virus in CD4(+) T cells and macrophages, which in turn led to elimination of the CD4(+) T cells and profound loss of immunocompetence in the infected animals.

Simian-human immunodeficiency virus (SHIV) containing the nef/long terminal repeat region of the highly virulent SIVsmmPBj14 causes PBj-like activation of cultured resting peripheral blood mononuclear cells, but the chimera showed No increase in virulence.

SIVsmmPBj14 is a highly pathogenic lentivirus which causes acute diarrhea, rash, massive lymphocyte proliferation predominantly in the gastrointestinal tract, and death within 7 to 14 days. In cell culture, the virus has mitogenic effects on resting macaque T lymphocytes. In contrast, SIVmac239 causes AIDS in rhesus macaques, generally within 2 years after inoculation. In a previous study, replacement of amino acid residues 17 and 18 of the Nef protein of SIVmac239 with the corresponding amino acid residues of the Nef protein of SIVsmmPBj14 yielded a PBj-like virus that caused extensive activation of resting T lymphocytes in cultures and acute PBj-like disease when inoculated into pig-tailed macaques. This study suggested that nef played a major role in both processes. In this study, we replaced the nef/long terminal repeat (LTR) region of a nonpathogenic simian-human immunodeficiency virus (SHIV), SHIVPPc, with the corresponding region from SIVsmmPBj14 and examined the biological properties of the resultant virus. Like SIVsmmPBj14, SHIVPPcPBjnef caused massive stimulation of resting peripheral blood mononuclear cells (PBMC), which then produced virus in the absence of extraneous interleukin 2. However, when inoculated into macaques, the virus failed to replicate productively or cause disease. Thus, while these results confirmed that the nef/LTR region of SIVsmmPBj14 played a major role in the activation of resting PBMC, duplication of the cellular activation process in macaques may require a further interaction between nef and the envelope glycoprotein of simian immunodeficiency virus because SHIV, containing the envelope of human immunodeficiency virus type 1, failed to cause activation in vivo.

Neuroinvasion by ovine lentivirus in infected sheep mediated by inflammatory cells associated with experimental allergic encephalomyelitis.

Maedi Visna Virus (MVV) is a prototypic lentivirus that causes infection only in cells of macrophage lineage, unlike the primate lentiviruses which infect both CD4+ T lymphocytes and macrophages. In primates, the earliest viral invasion is associated with the ability of the virus to infect and activate T cells which convey virus to the brain. Infected monocytes in blood rarely cause CNS infection in absence of activation of CD4+ T cells. In the face of lack of infection or activation of T cells by MVV in sheep, the question arises, how does MVV gain access to the brain to cause the classical lesions of visna? In previous studies on experimental induction of visna, sheep were inoculated with virus directly in the brain. In this study, we asked whether neuroinvasion by MVV would occur if sheep were inoculated with virus in a non-neural site. Nine sheep were inoculated intratracheally and all developed systemic infection when examined 3 weeks later. At this time, five were injected intramuscularly with brain white matter homogenized in Freund's complete adjuvant to induce EAE. None of the four animals inoculated with virus alone developed CNS infection despite typical lentiviral infection in lungs, lymphoid tissues and blood-borne mononuclear cells. In contrast, all five of the sheep injected with brain homogenate developed infection in the brain. Virus was produced by macrophages associated with the EAE lesions. This study illustrated that both activated T cells specific for antigen in the CNS and infected macrophages are essential for lentivirus neuropathogenesis.

Characterization of the pathogenic KU-SHIV model of acquired immunodeficiency syndrome in macaques.

By animal-to-animal passage in macaques we derived a pathogenic chimeric simian-human immunodeficiency virus (SHIV) that caused CD4+ T cell loss and AIDS in pigtail macaques and used it to inoculate 20 rhesus and pigtail macaques by the intravaginal and intravenous routes. On the basis of the outcome of infection and patterns of CD4+ T cell loss and viral load, disease was classified into four patterns: acute, subacute, chronic, and nonprogressive infection. During the study period, 15 of the 20 animals developed fatal disease, including AIDS, encephalitis, pneumonia, and severe anemia. Opportunistic pathogens identified in these animals included Pneumocystis, cytomegalovirus, Cryptosporidium, Toxoplasma, and Candida. No single parameter by itself predicted outcome, although a combination of low CD4+ T cell counts in blood, high plasma virus levels, and presence of autoantibodies to red blood cells reliably predicted a fatal outcome. Five animals (25%) died within 3 months of inoculation and constituted the group with acute disease, whereas the nine animals (45%) with subacute disease died between 3 and 8 months postinoculation. This 70% mortality within 8 months is significantly shorter than in HIV-1-infected human beings, of whom 70% develop fatal disease a decade after infection. SHIV infection in macaques provides a useful model with which to evaluate antiviral strategies, combining all the advantages of the SIVmac system, yet using a virus bearing the envelope gene of HIV-1.

Pathogenesis of ovine lentiviral encephalitis: derivation of a neurovirulent strain by in vivo passage.

The lentiviruses of sheep replicate almost exclusively in macrophages and cause chronic interstitial pneumonia, arthritis, and mastitis, but only rarely encephalitis. This study was undertaken to determine whether a non-neurovirulent field strain of ovine lentivirus isolated from joint fluid that replicated productively in lung and joint macrophages could be adapted to enter and replicate in the brain and cause encephalitis. The field isolate was passed seven times sequentially by intracerebral inoculation of sheep. The neuroadapted strain of virus caused severe encephalitis typical of visna in four of four sheep inoculated intracerebrally. The virus replicated to high titers in the brains of these animals and in cultured microglia. The inflammatory response in the brain was characterized by intense infiltrates of macrophages and CD8+ and CD4+ T cells. Many of the perivascular macrophages demonstrated TNF-alpha expression and there was upregulation of MHC Class II antigen expression on both inflammatory cells and endothelium. Inoculation of this neuroadapted virus into the bone marrow of three animals resulted in persistent infection and cell-associated viremia, but not encephalitis. Virus was not detected in brains from these animals, indicating that the virus was not neuroinvasive. These data suggest that neuroinvasiveness and neurovirulence are separate pathogenic determinants, both of which are required for the development of encephalitis during natural infection.

Signal Dependence on Irradiation Geometry of Cd1-xZnxTe Detectors for Digital X-Ray Imaging.

CdZnTe is one of the most promising semiconductor material in the field of digital X-ray imaging, and may be operated at room temperature. To improve the detector characteristics, ternary systems such as Cd1-xZnxTe were grown by the high pressure Bridgman (HPG) technique. The signal performance characteristics of quasi-resistive Cd1-xZnxTe semiconductor detectors, was studied at different directions of irradiation, within the X-ray diagnostic energy range. The experimental results suggest that the total efficiency of these semiconductor detectors depends upon the energy absorption efficiency as well as the charge collection efficiency. This imaging detector allows one to investigate methods to improve the detection and imaging performance parameters as part of the development of an X-ray imaging system.

Contrast Study of CdZnTe Detectors for Digital Mammography.

Experiments have been performed with the aim of optimizing the image quality parameters of CdZnTe detectors for digital mammography. A geometrical breast phantom has been designed, and the dependence of the contrast resolution of a planar CdZnTe detector on the phantom thickness has been experimentally determined. Specifically, the detected signal and noise contributions were measured and related to phantom thickness. The results of this study indicate that the CdZnTe detectors exhibit a high contrast resolution. On the other hand, the dynamic range of this detector can be improved significantly by further implementation of the data acquisition electronics.

Variations in lentiviral gene expression in monocyte-derived macrophages from naturally infected sheep.

Seventy-nine 1-year-old lambs from three individual farms and a feedlot were examined for natural lentivirus infection. We used three different methods to detect infection and to identify the stage of the ovine lentivirus life cycle in blood-derived macrophages. Cytopathic infectious virus was obtained from 14/14 Border Leicester animals obtained from a naturally infected flock. Neither virus particles, virus proteins, virus specific antibodies nor viral DNA were detected in samples from 34 lambs from two South Kansas City farms. However, among 31 feedlot lambs, we identified 11 infected animals. Specific viral proteins were immunoprecipitated from macrophages of one animal, but no infectious cytopathic virus was isolated from these cells. Cells from ten of the other feedlot animals harboured viral DNA but neither viral particles nor proteins could be detected by our techniques. Thus, in these naturally infected animals, the virus life cycle either proceeded to completion, subject to differentiation of infected precursor cells in blood, or remained arrested at the DNA stage despite maturation of monocytes to macrophages. Sequence analysis of the env gene of viral genomes from two of the ten feedlot sheep showed sequences distinct from those of known ovine and caprine lentiviruses. Surprisingly, these sequences have a higher identity (of nucleotide and derived amino acid sequences) to caprine arthritis-encephalitis virus than to the ovine prototype, maedi-visna virus. These data suggest that the ovine and caprine lentiviruses found in North American sheep may have a common ancestral genotype that is closely related to the caprine virus.

Restrictive type of replication of ovine/caprine lentiviruses in ovine fibroblast cell cultures.

Caprine arthritis-encephalitis virus (CAEV) is a natural lentivirus pathogen of goats. CAEV, like all members of the ovine/ caprine lentivirus family, has an in vivo tropism for cells of the monocyte/macrophage cell lineage and activation of viral gene expression is observed only following differentiation of monocytes to macrophages. In addition to cells of the monocyte/ macrophage lineage, CAEV and the closely related maedi visna virus of sheep (MVV) can also replicate productively in fibro-epithelial cells derived from synovial membrane of goats (GSM). However, these viruses varied greatly in their ability to replicate in fibroblasts. We studied the biological and biochemical properties of CAEV and maedi-visna virus (MVV) of sheep following inoculation into the three ovine/caprine cell types. Our data showed no substantial differences in virus titers, viral protein biosynthesis, or processing of the viral proteins between CAEV and MVV following inoculation into primary macrophages and GSM cells. However, unlike MVV, CAEV failed to replicate productively in ovine fibroblasts (sheep choroid plexus cells). This correlated with a specific but abnormal proteolytic cleavage of the envelope glycoprotein of the virus. This abnormal proteolytic cleavage represents a novel type of host cell restriction of lentivirus replication.

Initial characterization of viral sequences from a SHIV-inoculated pig-tailed macaque that developed AIDS.

In this study, we report on the derivation of a pathogenic SIV-HIV chimeric virus (SHIV) and the initial characterization of the viral sequences from the first (macaque PPc) of a series of pig-tailed macaques that developed CD4+ T cell loss and AIDS. Viral genes were amplified by PCR from the brain, lymphoid, and kidney tissues and their sequences compared to the original SHIV used to initiate passages in macaques. Our results show that the vpu gene, which was nonfunctional in the original SHIV, now coded for functional protein in macaque PPc. The tat and rev genes had no consensus changes but the nef gene had 4-5 consensus changes, depending on the tissue examined. The gp 120 gene had the highest number of nucleotide and amino acid substitution rates that varied from 0.64% to 1.44% and 1.17% to 3.71%, respectively, again depending on the tissue examined. These results suggest that a constellation of changes accumulated at the genomic level during the derivation of a SHIV that was pathogenic for pig-tailed macaques.