Processing, fusogenicity, virion incorporation and CXCR4-binding activity of a feline immunodeficiency virus envelope glycoprotein lacking the two conserved N-glycosylation sites at the C-terminus of the V3 domain.

The process of feline immunodeficiency virus (FIV) entry into its target cells is initiated by the association of the surface (SU) subunit of the viral envelope glycoprotein (Env) with the cellular receptors CD134 and CXCR4. This event is followed by the fusion of the viral and cellular membranes, which is mediated by the transmembrane (TM) subunit of Env. We and others have previously demonstrated that the V3 domain of the SU subunit of Env is essential for CXCR4 binding. Of note, there are two contiguous and highly conserved potential N-glycosylation sites ((418)NST(420) and (422)NLT(424)) located at the C-terminal side of the V3 domain. We therefore decided to study the relevance for Env functions of these N-glycosylation motifs and found that disruption of both of them by introducing the N418Q/N422Q double amino acid substitution drastically impairs Env processing into the SU and TM subunits. Moreover, the simultaneous mutation of these N-glycosylation sites prevents Env incorporation into virions and Env-mediated cell-to-cell fusion. Notably, a recombinant soluble version of the SU glycoprotein carrying the double amino acid replacement N418Q/N422Q at the V3 C-terminal side binds to CXCR4 with an efficiency similar to that of wild-type SU.

Infection with feline immunodeficiency virus alters intestinal epithelial transport and mucosal immune responses to probiotics.

HIV infection is associated with intestinal mucosal dysfunction and probiotics offer the therapeutic potential to enhance the mucosal barrier in HIV+ patients. To evaluate the response of immunocompromised hosts to probiotics, we orally administered Lactobacillus acidophilus to cats with chronic feline immunodeficiency virus (FIV) infection. FIV infection significantly affected transcellular, but not paracellular, transport of small molecules across the intestinal epithelium. Additionally, probiotic treatment of FIV+ cats resulted in changes in cytokine release and mucosal leukocyte percentages that were not paralleled in FIV- cats. These results suggest a novel role for FIV in upregulating transcellular transport across the gastrointestinal epithelial barrier and demonstrate the potential therapeutic use of probiotic bacteria to restore intestinal homeostasis.

Brain microbial populations in HIV/AIDS: α-proteobacteria predominate independent of host immune status.

The brain is assumed to be a sterile organ in the absence of disease although the impact of immune disruption is uncertain in terms of brain microbial diversity or quantity. To investigate microbial diversity and quantity in the brain, the profile of infectious agents was examined in pathologically normal and abnormal brains from persons with HIV/AIDS [HIV] (n = 12), other disease controls [ODC] (n = 14) and in cerebral surgical resections for epilepsy [SURG] (n = 6). Deep sequencing of cerebral white matter-derived RNA from the HIV (n = 4) and ODC (n = 4) patients and SURG (n = 2) groups revealed bacterially-encoded 16 s RNA sequences in all brain specimens with α-proteobacteria representing over 70% of bacterial sequences while the other 30% of bacterial classes varied widely. Bacterial rRNA was detected in white matter glial cells by in situ hybridization and peptidoglycan immunoreactivity was also localized principally in glia in human brains. Analyses of amplified bacterial 16 s rRNA sequences disclosed that Proteobacteria was the principal bacterial phylum in all human brain samples with similar bacterial rRNA quantities in HIV and ODC groups despite increased host neuroimmune responses in the HIV group. Exogenous viruses including bacteriophage and human herpes viruses-4, -5 and -6 were detected variably in autopsied brains from both clinical groups. Brains from SIV- and SHIV-infected macaques displayed a profile of bacterial phyla also dominated by Proteobacteria but bacterial sequences were not detected in experimentally FIV-infected cat or RAG1⁻/⁻ mouse brains. Intracerebral implantation of human brain homogenates into RAG1⁻/⁻ mice revealed a preponderance of α-proteobacteria 16 s RNA sequences in the brains of recipient mice at 7 weeks post-implantation, which was abrogated by prior heat-treatment of the brain homogenate. Thus, α-proteobacteria represented the major bacterial component of the primate brain's microbiome regardless of underlying immune status, which could be transferred into naïve hosts leading to microbial persistence in the brain.

Amyloidosis in association with spontaneous feline immunodeficiency virus infection.

Tissues from 34 naturally feline immunodeficiency virus (FIV)-infected cats, 13 asymptomatic cats and 21 cats with signs of feline acquired immunodeficiency syndrome (F-AIDS), and 35 FIV-seronegative subjects were examined to determine the presence of amyloid deposits. Twenty experimentally FIV-infected cats and five specific pathogen-free (SPF) control cats were also included in the study. Paraffin-embedded sections from kidney and other organs were submitted to histological and histochemical analysis. Amyloid deposits were identified by a modified Congo red stain and confirmed by electron microscopy to demonstrate the presence of amyloid fibrils in amyloid positive glomeruli. In all positive cases, secondary amyloidosis was identified with potassium permanganate pretreatment and amyloid type was further characterised by immunohistochemistry using primary antibodies against human AA and feline AL amyloids. Amyloid deposits were present in different tissues of 12/34 (35%) naturally FIV-infected cats (seven presenting F-AIDS and five in asymptomatic phase) and in 1/30 FIV-seronegative cats. All the experimentally FIV-infected and SPF subjects showed no amyloid deposits. Amyloidosis has been reported in human lentiviral infections, and the data reported here demonstrate the need, in naturally FIV-infected cats, to consider the presence of amyloidosis in differential diagnosis of hepatic and renal disorders to better assess the prognosis of the disease.

Time-course analysis of main markers of primary infection in cats with the feline immunodeficiency virus.

Studies of the response of the immune system to feline immunodeficiency virus (FIV) during primary infection have shown that a subpopulation of CD8(+) T-cells with an activated phenotype and reduced expression of the CD8ß chain (denoted CD8ß(low) T cells) expands to reach up to 80% of the total CD8(+) T cell count. The expansion of this subpopulation is considered to be a signature of FIV and an indicator of immune system alteration. We use a simple mathematical formalism to study the relationships over time between the dose of infection, the size of the CD8ß(low) population, and the circulating viral load in cats infected with FIV. Viremia profiles are described using a combination of two exponential laws, whereas the CD8ß(low) percentage (out of the total CD8(+) population) is represented by a Gompertz law including an expansion phase and a saturation phase. Model parameters are estimated with a population approach using data from 102 experimentally infected cats. We examine the dose of infection as a potential covariate of parameters. We find that the rates of increase of viral load and of CD8ß(low) percentage are both correlated with the dose of infection. Cats that develop strong acute viremia also show the largest degree of CD8ß(low) expansion. The two simple models are robust tools for analysing the time course of CD8ß(low) percentage and circulating viral load in FIV-infected cats and may be useful for generating new insights on the disease and on the design of therapeutic strategies, potentially applicable to HIV infection.

Feline tetherin is characterized by a short N-terminal region and is counteracted by the feline immunodeficiency virus envelope glycoprotein.

Tetherin (BST2) is the host cell factor that blocks the particle release of some enveloped viruses. Two putative feline tetherin proteins differing at the level of the N-terminal coding region have recently been described and tested for their antiviral activity. By cloning and comparing the two reported feline tetherins (called here cBST2(504) and cBST2*) and generating specific derivative mutants, this study provides evidence that feline tetherin has a shorter intracytoplasmic domain than those of other known homologues. The minimal tetherin promoter was identified and assayed for its ability to drive tetherin expression in an alpha interferon-inducible manner. We also demonstrated that cBST2(504) is able to dimerize, is localized at the cellular membrane, and impairs human immunodeficiency virus type 1 (HIV-1) particle release, regardless of the presence of the Vpu antagonist accessory protein. While cBST2(504) failed to restrict wild-type feline immunodeficiency virus (FIV) egress, FIV mutants, bearing a frameshift at the level of the envelope-encoding region, were potently blocked. The transient expression of the FIV envelope glycoprotein was able to rescue mutant particle release from feline tetherin-positive cells but did not antagonize human BST2 activity. Moreover, cBST2(504) was capable of specifically immunoprecipitating the FIV envelope glycoprotein. Finally, cBST2(504) also exerted its function on HIV-2 ROD10 and on the simian immunodeficiency virus SIVmac239. Taken together, these results show that feline tetherin does indeed have a short N-terminal region and that the FIV envelope glycoprotein is the predominant factor counteracting tetherin restriction.

Identification of a Cullin5-ElonginB-ElonginC E3 complex in degradation of feline immunodeficiency virus Vif-mediated feline APOBEC3 proteins.

Various feline APOBEC3 (fA3) proteins exhibit broad antiviral activities against a wide range of viruses, such as feline immunodeficiency virus (FIV), feline foamy virus (FFV), and feline leukemia virus (FeLV), as well as those of other species. This activity can be counteracted by the FIV Vif protein, but the mechanism by which FIV Vif suppresses fA3s is unknown. In the present study, we demonstrated that FIV Vif could act via a proteasome-dependent pathway to overcome fA3s. FIV Vif interacted with feline cellular proteins Cullin5 (Cul5), ElonginB, and ElonginC to form an E3 complex to induce degradation of fA3s. Both the dominant-negative Cul5 mutant and a C-terminal hydrophilic replacement ElonginC mutant potently disrupted the FIV Vif activity against fA3s. Furthermore, we identified a BC-box motif in FIV Vif that was essential for the recruitment of E3 ubiquitin ligase and also required for FIV Vif-mediated degradation of fA3s. Moreover, despite the lack of either a Cul5-box or a HCCH zinc-binding motif, FIV Vif specifically selected Cul5. Therefore, FIV Vif may interact with Cul5 via a novel mechanism. These finding imply that SOCS proteins may possess distinct mechanisms to bind Cul5 during formation of the Elongin-Cullin-SOCS box complex.

Multivariate statistical analyses demonstrate unique host immune responses to single and dual lentiviral infection.

BACKGROUND: Feline immunodeficiency virus (FIV) and human immunodeficiency virus (HIV) are recently identified lentiviruses that cause progressive immune decline and ultimately death in infected cats and humans. It is of great interest to understand how to prevent immune system collapse caused by these lentiviruses. We recently described that disease caused by a virulent FIV strain in cats can be attenuated if animals are first infected with a feline immunodeficiency virus derived from a wild cougar. The detailed temporal tracking of cat immunological parameters in response to two viral infections resulted in high-dimensional datasets containing variables that exhibit strong co-variation. Initial analyses of these complex data using univariate statistical techniques did not account for interactions among immunological response variables and therefore potentially obscured significant effects between infection state and immunological parameters. METHODOLOGY AND PRINCIPAL FINDINGS: Here, we apply a suite of multivariate statistical tools, including Principal Component Analysis, MANOVA and Linear Discriminant Analysis, to temporal immunological data resulting from FIV superinfection in domestic cats. We investigated the co-variation among immunological responses, the differences in immune parameters among four groups of five cats each (uninfected, single and dual infected animals), and the "immune profiles" that discriminate among them over the first four weeks following superinfection. Dual infected cats mount an immune response by 24 days post superinfection that is characterized by elevated levels of CD8 and CD25 cells and increased expression of IL4 and IFNgamma, and FAS. This profile discriminates dual infected cats from cats infected with FIV alone, which show high IL-10 and lower numbers of CD8 and CD25 cells. CONCLUSIONS: Multivariate statistical analyses demonstrate both the dynamic nature of the immune response to FIV single and dual infection and the development of a unique immunological profile in dual infected cats, which are protected from immune decline.

Effects of an oral superoxide dismutase enzyme supplementation on indices of oxidative stress, proviral load, and CD4:CD8 ratios in asymptomatic FIV-infected cats.

This study was designed to test the effect of antioxidant supplementation on feline immunodeficiency virus (FIV)-infected felines. Six acutely FIV-infected cats (> or =16 weeks post-inoculation) were given a propriety oral superoxide dismutase (SOD) supplement (Oxstrin; Nutramax Laboratories) for 30 days. Following supplementation, the erythrocyte SOD enzyme concentration was significantly greater in the supplemented FIV-infected group than the uninfected control group or the unsupplemented FIV-infected group. The CD4+ to CD8+ ratio increased significantly (0.66-0.88) in the SOD supplemented FIV-infected cats but not in the unsupplemented FIV-infected cats. Proviral load and reduced glutathione (GSH) levels in leukocyte cell types did not change significantly following supplementation. Antioxidant supplementation resulted in an increase in SOD levels, confirming the oral bioavailability of the compound in FIV-infected cats. This result warrants further investigation with trials of antioxidant therapy in FIV-infected cats that are showing clinical manifestations of their disease, as well as in other feline patients where oxidative stress likely contributes to disease pathogenesis, such as diabetes mellitus and chronic renal failure.

Expression of CD134 and CXCR4 mRNA in term placentas from FIV-infected and control cats.

Feline immunodeficiency virus (FIV) causes a natural infection of domestic cats that resembles HIV-1 in pathogenesis and disease progression. Feline AIDS is characterized by depression of the CD4+ T cell population and fatal opportunistic infections. Maternal-fetal transmission of FIV readily occurs under experimental conditions, resulting in infected viable kittens and resorbed or arrested fetal tissues. Although both FIV and HIV use the chemokine receptor CXCR4 as a co-receptor, FIV does not utilize CD4 as the primary receptor. Rather, CD134 (OX40), a T cell activation antigen and co-stimulatory molecule, is the primary receptor for FIV. We hypothesized that placental expression of CD134 and CXCR4 may render the placenta vulnerable to FIV infection, possibly facilitating efficient vertical transmission of FIV, and impact pregnancy outcome. The purpose of this project was to quantify the relative expression of CD134 and CXCR4 mRNA from the term placentas of three groups of cats: uninfected queens producing viable offspring, experimentally-infected queens producing only viable offspring, and experimentally-infected queens producing viable offspring among mostly non-viable fetuses. Total RNA was extracted from term placental tissues from all groups of cats. Real-time one-step reverse transcriptase-PCR was used to measure gene expression. The FIV receptors CD134 and CXCR4 were expressed in all late term feline placental tissues. Placentas from FIV-infected queens producing litters of only viable offspring expressed more CD134 and CXCR4 mRNA than those from uninfected queens, suggesting that infection may cause upregulation of the receptors. On the other hand, placentas from FIV-infected cats with non-successful pregnancies expressed similar levels of CD134 mRNA and slightly less CXCR4 mRNA than those from uninfected queens. Thus, it appears that cells expressing these receptors may play a role in pregnancy maintenance.

Oxidative stress during acute FIV infection in cats.

Oxidative stress is thought to contribute to the pathogenesis of HIV infection in humans. For example, CD4(+) T cells are particularly affected in HIV patients and oxidative stress may also contribute to impairment of neutrophil function in HIV/AIDS patients. Since cats infected with FIV develop many of the same immunological abnormalites as HIV-infected humans, we investigated effects of acute FIV infection on oxidative stress in cats. Cats were infected with a pathogenic strain of FIV and viral load, changes in neutrophil number, total blood glutathione, malondiadehye, antioxidant enzyme concentrations, and reduced glutathione (GSH) concentration in leukocytes were measured sequentially during the first 16 weeks of infection. We found that superoxide dismutase and glutathione peroxidase concentrations in whole blood increased significantly during acute FIV infection. In addition, neutrophil numbers increased significantly during this time period, though their intracellular GSH concentrations did not change. In contrast, the numbers of CD4(+) T cells decreased significantly and their intracellular GSH concentration increased significantly, while intracellular GSH concentrations were unchanged in CD8(+) T cells. However, by 16 weeks of infection, many of the abnormalities in oxidative balance had stabilized or returned to pre-inoculation values. These results suggest that acute infection with FIV causes oxidative stress in cats and that CD4(+) T cells appear to be preferentially affected. Further studies are required to determine whether early treatment with anti-oxidants may help ameliorate the decline in CD4(+) T cell number and function associated with acute FIV infection in cats.

Feline immunodeficiency virus neuropathogenesis: from cats to calcium.

Invasion of human immunodeficiency virus (HIV) into the central and peripheral nervous system produces a wide range of neurological symptoms, which continue to persist even with adequate therapeutic suppression of the systemic viremia. The development of therapies designed to prevent the neurological complications of HIV require a detailed understanding of the mechanisms of virus penetration into the nervous system, infection, and subsequent neuropathogenesis. These processes, however, are difficult to study in humans. The identification of animal lentiviruses similar to HIV has provided useful models of HIV infection that have greatly facilitated these efforts. This review summarizes contributions made from in vitro and in vivo studies on the infectious and pathological interactions of feline immunodeficiency virus (FIV) with the nervous system. In vivo studies on FIV have provided insights into the natural progression of CNS disease as well as the contribution of various risk factors. In vitro studies have contributed to our understanding of immune cell trafficking, CNS infection and neuropathogenesis. Together, these studies have made unique contributions to our understanding of (1) lentiviral interactions at the blood-cerebrospinal fluid (CSF) barrier within the choroid plexus, (2) early FIV invasion and pathogenesis in the brain, and (3) lentiviral effects on intracellular calcium deregulation and neuronal dysfunction. The ability to combine in vitro and in vivo studies on FIV offers enormous potential to explore neuropathogenic mechanisms and generate information necessary for the development of effective therapeutic interventions.

Didanosine causes sensory neuropathy in an HIV/AIDS animal model: impaired mitochondrial and neurotrophic factor gene expression.

Antiretroviral toxic neuropathy (ATN) has become a common peripheral neuropathy among HIV/AIDS patients, for which the underlying pathogenesis is uncertain. Indeed, no models exist for ATN that assess the interaction between retroviral infection and antiretroviral therapy. Herein, we developed ex vivo and in vivo models of ATN induced by didanosine (ddI) following infection by the lentivirus, feline immunodeficiency virus (FIV), permitting us to address the working hypothesis that ddI mediates ATN through mitochondrial injury in neurons. We investigated neuronal morphology, neurobehavioural testing, viral load, mitochondrial and neurotrophic factor gene expression after ddI treatment of FIV-infected and uninfected animals or dorsal root ganglia (DRG) cultures. ddI caused concentration-dependent neuronal injury in cultured feline DRGs (P < 0.05), together with reduced viral replication and diminished expression of mitochondrial cytochrome C oxidase subunit I gene (mtCOX I) and the neurotrophin, brain-derived neurotrophic factor (BDNF). Indeed, BDNF treatment reversed neuronal injury caused by FIV infection in the presence or absence of ddI exposure (P < 0.05). In vivo FIV infection revealed delays in withdrawal latency to a noxious stimulus, which were exacerbated by ddI treatment. Epidermal density of nerve endings was reduced after FIV infection (P < 0.05), especially with ddI treatment. Although viral replication in blood was suppressed in ddI-treated animals (P < 0.05), ddI had a limited effect on viral abundance in DRGs of the same animals. ddI decreased mtCOX I expression in DRG neurons of FIV-infected animals (P < 0.05). BDNF expression was downregulated by ddI in DRG Schwann cells following FIV infection. Thus, ddI treatment during FIV infection resulted in additive pathogenic effects contributing to the development of ATN, which was associated with mitochondrial injury on neurons and reduced BDNF production by Schwann cells in DRGs, highlighting the convergent pathogenic effects that antiretroviral drugs might have in patients with HIV infection.

Probing the interaction between feline immunodeficiency virus and CD134 by using the novel monoclonal antibody 7D6 and the CD134 (Ox40) ligand.

The feline immunodeficiency virus (FIV) targets activated CD4-positive helper T cells preferentially, inducing an AIDS-like immunodeficiency in its natural host species, the domestic cat. The primary receptor for FIV is CD134, a member of the tumor necrosis factor receptor superfamily, and all primary viral strains tested to date use CD134 for infection. We examined the expression of CD134 in the cat using a novel anti-feline CD134 monoclonal antibody (MAb), 7D6, and showed that as in rats and humans, CD134 expression is restricted tightly to CD4+, and not CD8+, T cells, consistent with the selective targeting of these cells by FIV. However, FIV is also macrophage tropic, and in chronic infection the viral tropism broadens to include B cells and CD8+ T cells. Using 7D6, we revealed CD134 expression on a B220-positive (B-cell) population and on cultured macrophages but not peripheral blood monocytes. Moreover, macrophage CD134 expression and FIV infection were enhanced by activation in response to bacterial lipopolysaccharide. Consistent with CD134 expression on human and murine T cells, feline CD134 was abundant on mitogen-stimulated CD4+ T cells, with weaker expression on CD8+ T cells, concordant with the expansion of FIV into CD8+ T cells with progression of the infection. The interaction between FIV and CD134 was probed using MAb 7D6 and soluble CD134 ligand (CD134L), revealing strain-specific differences in sensitivity to both 7D6 and CD134L. Infection with isolates such as PPR and B2542 was inhibited well by both 7D6 and CD134L, suggesting a lower affinity of interaction. In contrast, GL8, CPG, and NCSU were relatively refractory to inhibition by both 7D6 and CD134L and, accordingly, may have a higher-affinity interaction with CD134, permitting infection of cells where CD134 levels are limiting.

Altered tryptophan metabolism in FIV-positive cats.

BACKGROUND: Feline immunodeficiency virus (FIV) is analogous to human immunodeficiency virus, the causative agent of human acquired immunodeficiency syndrome (AIDS). In AIDS patients, a progressive reduction in serum tryptophan concentration occurs because of activation of an inducible tryptophan degradation pathway mediated by elevated lamda-interferon production. HYPOTHESIS: Cats infected with FIV have increased tryptophan catabolism evidenced by reduced circulating concentrations of tryptophan and increased concentrations of the tryptophan catabolite kynurenine. ANIMALS: Convenience sample of 235 cats submitted for diagnostic FIV serology (115 FIV-negative and 120 FIV-positive cats). METHODS: Retrospective, cross-sectional study. Serum was assayed for tryptophan and kynurenine using a high performance liquid chromatography assay with fluorescence and ultraviolet detection, respectively. RESULTS: Tryptophan and kynurenine concentrations were log-normally distributed. Geometric mean concentrations were: tryptophan: FIV-positive 30.6 microM (95% CI: 26.8 34.8 microM), FIV-negative 48.9 [microM (95% CI: 43.6-54.9 microM) (P < .001); kynurenine: FIV-positive 22.7 microM (95% CI: 25.5-10.9 microM), FIV-negative 9.9 microM (95% CI: 20.3-9.03 microM) (P < .001). The ratio of kynurenine to tryptophan was: FIV-positive 4.93 (95% CI: 5.62-4.32), FIV-negative 1.34 (95% CI: 1.53 1.17) (P < .0001). CONCLUSIONS AND CLINICAL IMPORTANCE: Serum tryptophan concentration was significantly lower and serum kynurenine concentration was significantly higher in FIV-positive cats. The kynurenine: tryptophan ratio was >3-fold higher in FIV-positive animals, indicating increased tryptophan catabolism in this group. Dietary or pharmacologic intervention to support serum tryptophan concentrations has been shown to be clinically useful in humans with AIDS and might be applicable to cats with FIV infection.

Evaluation of a novel nested PCR for the routine diagnosis of feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV).

Laboratory diagnosis of feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) usually involves both viruses, as the clinical signs are similar and coinfection may occur. Serological methods may not represent an accurate diagnosis: maternal antibodies or cross-reactions may give false positive results to FIV, and false negative results may occur in latent FeLV status, or in certain FIV infection stages. A nested polymerase chain reaction (PCR) technique was designed to detect FeLV, FIV and feline endogenous retrovirus simultaneously. The detection of endogenous sequences was considered indicative of successful DNA extraction. The technique was used to diagnose FIV and FeLV in the blood cells of 179 cats. The kappa value with the serological data was 0.69 for FeLV and 0.87 for FIV. The joint detection of FeLV and FIV by this novel nested PCR is sensitive, specific, fast and convenient, and its applicability for clinical diagnosis is promising, as the direct evidence of the presence of the virus is more realistic than the indirect data provided by the serological detection.

In vivo pharmacokinetics and toxicity profile of the anti-HIV agent stampidine in dogs and feline immunodeficiency virus-infected cats.

The pharmacokinetics and toxicity profile of stampidine (STAMP, DDE-113, HI-113, N-[p-(4-bromophenyl)-2',3'-didehydro-3'-deoxy-5'-thymidylyl]-L-alanine methyl ester, CAS 217178-62-6) were studied in beagle dogs and feline immunodeficiency virus-infected domestic cats. Therapeutic plasma concentrations of STAMP 3-4 logs higher than its IC50 value can be achieved after its p.o. administration to dogs as well as cats at the 100 mg/kg nontoxic dose level. In accordance with its safety profile in rodent species, a 4- to 7-week STAMP treatment course with twice daily administration of hard gelatin capsules containing 25-100 mg/kg (50-200 mg/kg/ day) STAMP was very well-tolerated by dogs and cats at cumulative dose levels as high as 8.4 g/kg. Except for the sporadic occurrence of nausea and vomiting after its administration and elevation of serum ALT levels in some of the cats, STAMP therapy was not associated with any clinical or laboratory evidence of toxicity. No STAMP-related toxic lesions were found in any of the organs from STAMP-treated cats or dogs. These findings encourage the further development of stampidine for possible clinical use in HIV-infected persons.

Glycan moiety modifications of feline alpha1-acid glycoprotein in retrovirus (FIV, FeLV) affected cats.

alpha1-Acid glycoprotein (AGP) is considered one of the major acute phase proteins in cats. In humans, AGP is a heavily glycosylated protein that undergoes several modifications of its glycan moiety during acute and chronic inflammatory pathologies. In this paper we present the feline AGPs (fAGP) glycan moiety modifications in the course of two prevalent feline diseases, the FIV (feline immunodeficiency virus) dependent feline acquired viral immunodeficiency and the feline leukemia virus (FeLV) associated lymphoma. The glycan moiety of fAGP was investigated by means of the binding of its oligosaccharides residues with specific lectins. Four lectins were used: Sambucus nigra agglutinin I and Maackia amurensis agglutinin lectins were used to detect sialic acid residues, Aleuria aurantia lectin was used to detect L-fucose residues and Concanavalin A was used to evaluate the degree of branching. It was found that fAGP undergoes several post-translational modifications of its glycan pattern: in particular the degree of sialylation is increased in FeLV-positive cats diagnosed with lymphoma, while FeLV-positive that did not presented any specific clinical signs cats do not present any increase of expression of sialic acid on the surface. Furthermore, FIV induced a modification of the glycan moiety of fAGP, which however varied widely among individuals. In order to determine the number and the position of oligosaccharide chains, the cDNA sequence of fAGP was also determined. The translation of the mature fAGP coding sequence gave rise to a sequence of 183 residues, with five potential N-glycosylation sites, but also with seven potential phosphorylation sites.

Placental immunopathology and pregnancy failure in the FIV-infected cat.

Placental HIV infections frequently result in infected babies or miscarriage. Aberrant placental cytokine expression during HIV infections may facilitate transplacental viral transmission or pregnancy perturbation. The feline immunodeficiency virus (FIV)-infected cat is a model for HIV infections due to similarities in biology and clinical disease. The purpose of this study was to evaluate placental immunomodulator expression and reproductive outcome using the FIV-infected cat model. Kittens were cesarean delivered from FIV-B-2542-infected and control queens near term; placental and fetal tissues were collected. Real-time RT-PCR was used to measure expression of representative placental Th1 cytokines, interleukin-1beta (IL-1beta) and interferon-gamma (IFN-gamma), a Th2 cytokine, IL-10, and chemokine receptor CXCR4. On average, control queens delivered 3.8 kittens/litter; 1 of 31 kittens (3.2%) was non-viable. FIV-infected queens produced 2.7 kittens/litter; 15 of 25 concepti (60%) were non-viable. FIV was detected in 14 of 15 placentas (93%) and 21 of 22 fetuses (95%) using PCR. Placental immunomodulator expression did not differ significantly when placentas from infected cats were compared to those of control cats. However, elevated expression of Th1 cytokines and increased Th1/Th2 ratios (IL-1beta/IL-10) occurred in placentas from resorptions. Therefore, increased placental Th1 cytokine expression was associated with pregnancy failure in the FIV-infected cat.

Bold attitude makes male urban feral domestic cats more vulnerable to Feline Immunodeficiency Virus.

Individual differences in behaviour are a phenomenon that is more and more attracting the attention of scientists. Among the other reasons, behavioural individuality occurs because selection favours the adoption of different tactics by individuals. It is now widely recognized that within many vertebrate species, individuals vary along an axis the extremes of which are represented by individuals 'bold' and 'shy', sometimes called 'proactive' and 'reactive'. Here we present the case of feral domestic cats (Felis catus L.) living in group in the urban environment where showing bold attitudes is linked to the benefit of a high annual reproductive success but, on the other hand, to a high probability to be infected by the Feline Immunodeficiency Virus (FIV), a lethal disease caused by a retrovirus. In this species, natural selection has probably favoured proactive temperament in spite of the cost represented by getting the disease. In fact, proactive individuals, even if FIV positive, reproduce more than reactive individuals before the last stage of FIV-infection (AIDS) characterized by a loss of immunological defences and subsequent opportunistic infections. Evolutionary implications are discussed.