Red elemental selenium (Se0 ) improves the immunoactivities of EPC cells, crucian carp and zebrafish against spring viraemia of carp virus.

Selenium, as an essential trace element, interferes through selenoproteins in many physiological processes of plants and mammals. Its antiviral activity has recently attracted much attention because selenium improves the antiviral capacity of animal cells against a few viruses relevant to human diseases. In this study, the red elemental selenium was purified from the fermentative culture of Herbaspirillum camelliae WT00C and then used to culture epithelioma papulosum cyprinid (EPC) cells or feed crucian carp and zebrafish. Finally, its antiviral effects were investigated at the cell level and living fishes after spring viraemia of carp virus infection. At the cell level, 5, 10 and 20 µg ml-1 red elemental selenium significantly induced the expression of interferon (IFN) and ISG15 genes in EPC cells. The viral TCID50 (50% tissue culture infective dose) values in the EPC cells incubated with 5, 10 and 20 µg ml-1 red elemental selenium were significantly less than those of the control. More expression of IFN and ISG15 genes and less TCID50 values indicate that red elemental selenium indeed improves the antiviral capability of EPC cells. In the crucian carp fed with the food containing 5 and 10 µg g-1 red elemental selenium, IFN expressions showed 13- and 39-fold increases at the 16th day of post-injection, and its expression was dependent on selenium concentrations. Meanwhile, no fish death occurred in all the experimental groups. In the zebrafish fed with the red worm containing 5 µg g-1 red elemental selenium, IFN and Mx expressions and survival rate were significantly higher than those of the control. The results of this study show that red elemental selenium indeed improves the antiviral activity of fish. The antiviral effects of selenium mainly come from its immune regulation through its incorporation into selenoproteins. The optimum level of selenium contributes to improving fish immunity, whereas excess selenium causes excessive immune and inflammatory responses.

Evaluation of PRRSv specific, maternally derived and induced immune response in Ingelvac PRRSFLEX EU vaccinated piglets in the presence of maternally transferred immunity.

In this study, we analyzed PRRS virus (PRRSv) specific lymphocyte function in piglets vaccinated with Ingelvac PRRSFLEX EU® at two and three weeks of age in the presence of homologous maternal immunity. Complete analysis of maternal immunity to PRRSv was evaluated postpartum, as well as passive transfer of antibodies and T cells to the piglet through colostrum intake and before and after challenge with a heterologous PRRSv at ten weeks of age. Maternal-derived antibodies were detected in piglets but declined quickly after weaning. However, vaccinated animals restored PRRSv-specific antibody levels by anamnestic response to vaccination. Cell analysis in colostrum and milk revealed presence of PRRSv-specific immune cells at suckling with higher concentrations found in colostrum than in milk. In addition, colostrum and milk contained PRRSv-specific IgA and IgG that may contribute to protection of newborn piglets. Despite the presence of PRRSv-specific Peripheral Blood Mononuclear cells (PBMCs) in colostrum and milk, no PRRSv-specific cells could be detected from blood of the piglets at one or two weeks of life. Nevertheless, cellular immunity was detectable in pre-challenged piglets up to 7 weeks after vaccination while the non-vaccinated control group showed no interferon (IFN) γ response to PRRSv stimulation. After challenge, all piglets developed a PRRSv-specific IFNγ-response, which was more robust at significantly higher levels in vaccinated animals compared to the primary response to PRRSv in non-vaccinated animals. Cytokine analysis in the lung lumen showed a reduction of pro-inflammatory responses to PRRSv challenge in vaccinated animals, especially reduced interferon (IFN) α levels. In conclusion, vaccination of maternally positive piglets at 2 and 3 weeks of age with Ingelvac PRRSFLEX EU induced a humoral and cellular immune response to PRRSv and provided protection against virulent, heterologous PRRSv challenge.

Plasmodium co-infection protects against chikungunya virus-induced pathologies.

Co-infection with Plasmodium and chikungunya virus (CHIKV) has been reported in humans, but the impact of co-infection on pathogenesis remains unclear. Here, we show that prior exposure to Plasmodium suppresses CHIKV-associated pathologies in mice. Mechanistically, Plasmodium infection induces IFNγ, which reduces viraemia of a subsequent CHIKV infection and suppresses tissue viral load and joint inflammation. Conversely, concomitant infection with both pathogens limits the peak of joint inflammation with no effect on CHIKV viraemia. Reduced peak joint inflammation is regulated by elevated apoptosis of CD4+ T-cells in the lymph nodes and disrupted CXCR3-mediated CD4+ T-cell migration that abolishes their infiltration into the joints. Virus clearance from tissues is delayed in both infection scenarios, and is associated with a disruption of B cell affinity-maturation in the spleen that reduces CHIKV-neutralizing antibody production.

Effect of Maternal Antibody Transfer on Antibody Dynamics and Control of Porcine Circovirus Type 2 Infection in Offspring.

Sow immunity plays an important role in preventing viral infection and disease in newborn piglets. Vertical transmission of porcine circovirus type 2 (PCV2) may perpetuate porcine circovirus associated disease (PCVAD) in newborn and growing pigs. Hence, the immunological effects of maternal immunoglobulin transfer of PCV2-specific antibodies on PCV2 viremia and immune response in piglets in commercial swine herds were evaluated. Sow vaccination has been shown to reduce viral shedding and viremia, and increases the neutralizing antibody (NA) titers. Since NAs are important for control of PCVAD and mammary secretions may contain high anti-PCV2 NA levels, we examined the PCV2 NA levels in colostrum, milk, sow serum, and piglet serum over time to investigate an association between NA levels and protection against infection. NA titers were remarkably high (up to 10-6 50% neutralizing titer) in sow serum and colostrum on all farms regardless of viremia levels. In piglets vaccinated at 3 weeks of age, NA titers peaked at 10 weeks of age and continued to maintain high viral neutralizing titers to slaughter. The impact of maternally derived neutralizing activity was most evident during the suckling period. Although PCV2 was transmitted from sows to piglets in colostrum, piglets were largely nonviremic at weaning. Thus, NAs appear to control or suppress initial infection even though they are unable to clear or prevent infection later in life.

Choreito formula for BK virus-associated hemorrhagic cystitis after allogeneic hematopoietic stem cell transplantation.

Therapy for BK virus (BKV)-associated hemorrhagic cystitis (BKV-HC) is limited after hematopoietic stem cell transplantation (HSCT). We examined whether choreito, a formula from Japanese traditional Kampo medicine, is effective for treating BKV-HC. Among children who underwent allogeneic HSCT between October 2006 and March 2014, 14 were diagnosed with BKV-HC (median, 36 days; range, 14 to 330 days) after HSCT, and 6 consecutive children received pharmaceutical-grade choreito extract granules. The hematuria grade before treatment was significantly higher in the choreito group than in the nonchoreito group (P = .018). The duration from therapy to complete resolution was significantly shorter in the choreito group (median, 9 days; range, 4 to 17 days) than in the nonchoreito group (median, 17 days; range, 15 to 66 days; P = .037). In 11 children with macroscopic hematuria, the duration from treatment to resolution of macroscopic hematuria was significantly shorter in the choreito group than in the nonchoreito group (median, 2 days versus 11 days; P = .0043). The BKV load in urine was significantly decreased 1 month after choreito administration. No adverse effects related to choreito administration were observed. Choreito may be a safe and considerably promising therapy for the hemostasis of BKV-HC after HSCT.

In vivo blockade of the programmed cell death-1 pathway using soluble recombinant PD-1-Fc enhances CD4+ and CD8+ T cell responses but has limited clinical benefit.

The programmed cell death-1 (PD-1)/programmed cell death ligand-1 pathway has been shown to limit cell-mediated effector functions during chronic viral infections impeding clearance of pathogens. As a strategy to reverse this exhaustion and increase T cell polyfunctionality, PD-1 ligands were blocked in vivo using a recombinant macaque PD-1 fused to a macaque Ig-Fc (rPD-1-Fc) in SIVmac239-infected rhesus macaques during the early chronic phase of infection, either alone or in combination with antiretroviral therapy. In vitro blockade showed improvement of Ag-specific CD4(+) and CD8(+) T cells from monkeys chronically infected with SIV. Of note, a prolonged 5-d blockade in culture was beneficial for both gag-specific CD4(+) and CD8(+) T cells based on proliferation and dual cytokine production. Although the in vivo administration of rPD-1-Fc induced enhanced SIV-specific CD4 and CD8 T cell proliferation both in the blood and gut, it failed to alter plasma viremia. However, rPD-1-Fc administration in the context of antiretroviral therapy interruption induced a significant delay of viral load rebound. In addition, rPD-1-Fc administration in MamuA*001(+) monkeys led to both an increase in the frequencies and Ki67 expression of GagCM9(+) CD8(+) T cells in the blood and rectal mucosa and polyfunctionality of GagCM9(+) CD8(+) T cells in blood. In conclusion, however, our data suggest that PD-1/programmed cell death ligand-1 blockade using soluble rPD-1-Fc instead of anti-PD-1 mAb, although effective in rescuing the effector function of SIV-specific CD4(+) and CD8(+) T cells during the early chronic phase of infection, has limited clinical benefit.

Dynamics of antibody response and viraemia following natural infection of porcine circovirus 2 (PCV-2) in a conventional pig herd.

Porcine circovirus 2 (PCV-2) is a primary agent of post-weaning multi-systemic wasting syndrome (PMWS), ubiquitous in pig herds. The course of viraemia and seroconversion in naturally infected pigs were investigated in piglets from the 2nd week of their life. Piglets were divided into seropositive (Ab(+)) and seronegative (Ab(-)) groups. Subsequently, after vaccination against PCV-2 (Ingelvac(®) CIRCOFLEX™, Böehringer Ingelheim), they were further divided into non-vaccinated seronegative (NVAC/Ab(-)) and seropositive (NVAC/Ab(+)), and vaccinated seronegative (VAC/Ab(-)) and seropositive (VAC/Ab(+)). PCV-2 colostral antibodies failed to prevent development of natural PCV-2 infection in conventional piglets; however, this occurred at a higher age in comparison with seronegative pigs. Neither colostral nor post-infection antibodies prevented development of viraemia, which persisted up to the end of the study (the 19th week), but without clinical signs of PMWS. Vaccination failed to prevent development of natural PCV-2 infection, but viraemia was limited to between the 8th and 10th week. The presence of colostral anti-PCV-2 antibodies did not show any untoward effect to vaccination; on the contrary, VAC/Ab(+) animals showed the lowest titre of viraemia.

Fetal infections and antibody profiles in pigs naturally infected with porcine circovirus type 2 (PCV2).

The aim of this study was to describe early infections with porcine circovirus type 2 (PCV2) in naturally infected piglets and the piglets' serologic profiles. A total of 20 sows (15 PCV2-vaccinated and 5 unvaccinated) and 100 newborn piglets were studied. Colostrum and serum of the sows and serum of the presuckling piglets were obtained on the day of parturition. Milk samples were collected on day 20 postpartum. Blood samples were taken and the piglets weighed on days 1, 20, 42, 63, and 84 postpartum. Colostrum and milk were evaluated for infectious PCV2 and for PCV2 total antibody (TA), neutralizing antibody (NA), and IgA. Serum samples were evaluated for PCV2 TA, NA, IgA, IgM, and DNA. The sows had high levels of TA and NA in serum and colostrum; however, 11 and 5, respectively, of the 20 colostrum and milk samples contained infectious PCV2. In the serum, PCV2 DNA and IgM were detected in 17 and 5, respectively, of the 20 sows. Nine piglets were born with PCV2 antibodies, which indicates in utero transmission of PCV2 after the period of immunocompetence (> 70 d of gestation). On day 1 postpartum, PCV2 DNA was detected in 29 of the 100 serum samples from the piglets. There was no difference between the weights of viremic and nonviremic piglets throughout the study. In conclusion, even on farms with sows that have high PCV2 antibody titers, vertical transmission of PCV2 may occur, resulting in piglet infection.

Animal models of dengue virus infection.

The development of animal models of dengue virus (DENV) infection and disease has been challenging, as epidemic DENV does not naturally infect non-human species. Non-human primates (NHPs) can sustain viral replication in relevant cell types and develop a robust immune response, but they do not develop overt disease. In contrast, certain immunodeficient mouse models infected with mouse-adapted DENV strains show signs of severe disease similar to the 'vascular-leak' syndrome seen in severe dengue in humans. Humanized mouse models can sustain DENV replication and show some signs of disease, but further development is needed to validate the immune response. Classically, immunocompetent mice infected with DENV do not manifest disease or else develop paralysis when inoculated intracranially; however, a new model using high doses of DENV has recently been shown to develop hemorrhagic signs after infection. Overall, each model has its advantages and disadvantages and is differentially suited for studies of dengue pathogenesis and immunopathogenesis and/or pre-clinical testing of antiviral drugs and vaccines.

Effect of porcine circovirus type 2 (PCV2) vaccination of the dam on PCV2 replication in utero.

The aims of this study were to determine if porcine circovirus type 2 (PCV2) vaccination of the dam is effective in preventing fetal PCV2 infection and reproductive failure. Twelve pregnant, PCV2-naïve sows were randomly divided into four groups, with three sows in each group. Group 1 sows served as noninoculated, nonvaccinated negative controls, group 2 sows were vaccinated with a commercially available PCV2 vaccine at 28 days of gestation and were not inoculated, group 3 sows were vaccinated at 28 days of gestation and inoculated with PCV2b at 56 days of gestation, and group 4 sows were inoculated with PCV2b but were not vaccinated. Serum samples from all sows were collected weekly throughout the gestation period, and sows were allowed to farrow naturally. At parturition, sow colostrum samples, presuckle serum samples, and tissues from the piglets were collected. Reproductive failure was not observed under the study conditions. PCV2 vaccination induced PCV2-specific immunoglobulin G and serum neutralizing antibodies in sows from groups 2 and 3 and prevented detectable PCV2 viremia in the dams after challenge. In group 3, PCV2 DNA was detected in colostrum samples, fetuses, and live-born pigs; however, microscopic lesions and PCV2-specific antigen were not present in any of the fetuses in this group. The results from this study indicate that vertical transmission of PCV2 can occur in PCV2-vaccinated dams.

Preclinical studies of human immunodeficiency virus/AIDS vaccines: inverse correlation between avidity of anti-Env antibodies and peak postchallenge viremia.

A major challenge for human immunodeficiency virus (HIV)/AIDS vaccines is the elicitation of anti-Env antibodies (Ab) capable of neutralizing the diversity of isolates in the pandemic. Here, we show that high-avidity, but nonneutralizing, Abs can have an inverse correlation with peak postchallenge viremia for a heterologous challenge. Vaccine studies were conducted in rhesus macaques using DNA priming followed by modified vaccinia Ankara boosting with HIV type 1 (HIV-1) immunogens that express virus-like particles displaying CCR5-tropic clade B (strain ADA) or clade C (IN98012) Envs. Rhesus granulocyte-macrophage colony-stimulating factor was used as an adjuvant for enhancing the avidity of anti-Env Ab responses. Challenge was with simian/human immunodeficiency virus (SHIV)-162P3, a CCR5-tropic clade B chimera of SIV and HIV-1. Within the groups receiving the clade B vaccine, a strong inverse correlation was found between the avidity of anti-Env Abs and peak postchallenge viremia. This correlation required the use of native but not gp120 or gp140 forms of Env for avidity assays. The high-avidity Ab elicited by the ADA Env had excellent breadth for the Envs of incident clade B but not clade C isolates, whereas the high-avidity Ab elicited by the IN98012 Env had excellent breadth for incident clade C but not clade B isolates. High-avidity Ab elicited by a SHIV vaccine with a dual-tropic clade B Env (89.6) had limited breadth for incident isolates. Our results suggest that certain Envs can elicit nonneutralizing but high-avidity Ab with broad potential for blunting incident infections of the same clade.

Short communication: no evidence of occult SHIV infection as demonstrated by CD8+ cell depletion after chemoprophylaxis-induced protection from mucosal infection in rhesus macaques.

Preexposure prophylaxis (PrEP) with antiretroviral drugs constitutes a promising strategy for HIV prevention. Potent PrEP regimens with reverse transcriptase inhibitors can prevent detectable SHIV infection in a repeated low-dose macaque model that resembles human transmission, supporting plans to quickly move this approach into human trials. However, the possibility remains that extremely low levels of virus replication could nonetheless occur during PrEP and seed viral reservoirs in tissues. Therefore, seemingly protected macaques may harbor occult virus that may be initially contained by cytotoxic T cells, but could emerge later. To explore this possibility, we studied whether CD8(+) cells suppress viremia in four rhesus macaques apparently protected by daily or intermittent Truvada (FTC and tenofovir) during 14 low-dose, rectal SHIV(SF162P3) challenges and during a subsequent drug washout period. CD8(+) cells were efficiently ablated with antibodies in these and two additional control macaques that were previously infected but had reached undetectable virus set points. During 4 weeks of follow-up, all four macaques remained free of plasma viremia and provirus in blood lymphocytes. In contrast, plasma viremia resurged to 10(6) to 10(7) copies per milliliter within 2 weeks in both control macaques. Thus, these results indicate that the undetectable viremia in the PrEP-protected macaques was not due to CD8(+) cells that were containing a low-level infection. Rather, the PrEP treatment created conditions in which infection was prevented, eliminated, or controlled by unknown mechanisms. These data provide important information for PrEP usage to prevent HIV transmission, and fully support the continued pursuit of PrEP prevention measures in humans.

A dengue fever viremia model in mice shows reduction in viral replication and suppression of the inflammatory response after treatment with antiviral drugs.

Dengue fever is an emerging arboviral disease for which no vaccine or antiviral treatment exists and that causes thousands of fatalities each year. To develop an in vivo test system for antidengue drugs, AG129 mice, which are deficient for the interferon- alpha / beta and - gamma receptors, were injected with unadapted dengue virus, resulting in a dose-dependent transient viremia lasting several days and peaking on day 3 after infection. Additionally, nonstructural protein 1, increased levels of proinflammatory cytokines, and neutralizing IgM and IgG antibodies were found, and mice had splenomegaly. Oral administration of the antiviral compounds 7-deaza-2'-C-methyl-adenosine, N-nonyl-deoxynojirimycin, or 6-O-butanoyl castanospermine significantly reduced viremia in a dose-dependent manner, even after delayed treatment, leading to a reduction of splenomegaly and proinflammatory cytokine levels. The results validate this dengue viremia mouse model as a suitable system for testing antidengue drugs and indicate that antiviral treatment during the acute phase of dengue fever can reduce the severity of the disease.

Control of simian/human immunodeficiency virus viremia and disease progression after IL-2-augmented DNA-modified vaccinia virus Ankara nasal vaccination in nonhuman primates.

A successful HIV vaccine may need to stimulate antiviral immunity in mucosal and systemic immune compartments, because HIV transmission occurs predominantly at mucosal sites. We report here the results of a combined DNA-modified vaccinia virus Ankara (MVA) vaccine approach that stimulated simian/human immunodeficiency virus (SHIV)-specific immune responses by vaccination at the nasal mucosa. Fifteen male rhesus macaques, divided into three groups, received three nasal vaccinations on day 1, wk 9, and wk 25 with a SHIV DNA plasmid producing noninfectious viral particles (group 1), or SHIV DNA plus IL-2/Ig DNA (group 2), or SHIV DNA plus IL-12 DNA (group 3). On wk 33, all macaques were boosted with rMVA expressing SIV Gag-Pol and HIV Env 89.6P, administered nasally. Humoral responses were evaluated by measuring SHIV-specific IgG and neutralizing Abs in plasma, and SHIV-specific IgA in rectal secretions. Cellular responses were monitored by evaluating blood-derived virus-specific IFN-gamma-secreting cells and TNF-alpha-expressing CD8+ T cells, and blood- and rectally derived p11C tetramer-positive T cells. Many of the vaccinated animals developed both mucosal and systemic humoral and cell-mediated anti-SHIV immune responses, although the responses were not homogenous among animals in the different groups. After rectal challenge of vaccinated and naive animals with SHIV89.6P, all animals became infected. However a subset, including all group 2 animals, were protected from CD4+ T cell loss and AIDS development. Taken together, these data indicate that nasal vaccination with SHIV-DNA plus IL-2/Ig DNA and rMVA can provide significant protection from disease progression.

Effect of dietary Echinacea purpurea on viremia and performance in porcine reproductive and respiratory syndrome virus-infected nursery pigs.

The effect of dietary Echinacea purpurea on performance, viremia, and ontogeny of the humoral antibody response against porcine reproductive and respiratory syndrome virus (PRRSV) infection was evaluated in weaned pigs. In three replicates, 120 weaned pigs (25 +/- 1 d of age; 8.46 +/- 0.48 kg of BW) from a PRRSV-naive herd were allotted randomly to one of eight pens (diets) in two separate rooms (four pens/room), with each pen containing five pigs. Pigs began one of four dietary treatments (as-fed basis) 1 wk before inoculation with PRRSV: 1) basal diet composed of corn, soybean meal, whey, and essential vitamins and minerals; 2) basal diet plus carbadox (0.055 g/kg of diet; as-fed basis); 3) basal diet plus Echinacea 2% (2% of the total diet); 4) basal diet plus Echinacea 4% (4% of the total diet). The diets were formulated to be isocaloric and isolysinic. Echinacea purpurea was purchased in powder form and determined by chemical analysis to contain 1.35% cichoric acid (as-fed basis). Seven days after starting the diets, all pigs in one room were intranasally inoculated with PRRSV isolate ATCC VR-2332 at a concentration of 10(4) tissue culture infectious dose50/mL. To monitor the effects of Echinacea and PRRSV challenge, BW and blood samples were obtained from all pigs at 7-d intervals. Serum samples were analyzed for the presence of PRRSV and PRRSV-specific antibodies. All challenged pigs became infected with PRRSV, and all unchallenged pigs remained free of infection. No differences (P > 0.10) in ADG, ADFI, or gain:feed (G:F) were observed in PRRSV-challenged compared with unchallenged animals. For PRRSV-challenged animals receiving diets supplemented with Echinacea at 2 or 4%, no differences (P > 0.10) were observed in ADG, ADFI, or G:F ratio. Among PRRSV-challenged pigs, dietary Echinacea did not affect (P > 0.10) the rate or level of the ELISA-detectable antibody response from d 7 to 42 or the level and duration of PRRSV in serum. For PRRSV-unchallenged animals receiving diets supplemented with Echinacea at 2 or 4%, no differences (P > 0.10) were observed in ADG, ADFI, and G:F ratio. Under the conditions of this study, dietary Echinacea did not enhance growth, exhibit antiviral effects to PRRSV, or show any evidence of immune enhancing properties.

16alpha-Bromo-epiandrosterone therapy modulates experimental feline immunodeficiency virus viremia: initial enhancement leading to long-term suppression.

16alpha-Bromo-epiandrosterone (epiBr), a synthetic derivative of the natural hormone dehyroepiandrosterone (DHEA), was evaluated for its effects on feline immunodeficiency virus (FIV) infection in experimental cats. The rationale for this study was based on the ability of DHEA to significantly reduce the mortality to viral infections in mice. DHEA and epiBr also have demonstrable in vitro anti-viral activity for both HIV-1 and FIV. Preliminary pharmacokinetic studies in cats demonstrated that subcutaneously injected epiBr was rapidly absorbed, completely metabolized, and nontoxic. Metabolites were excreted in both urine and feces, with the latter having the most complex pattern of breakdown products. Cats were then divided into four groups; two groups were infected with FIV and two uninfected. Two groups, one infected and one uninfected were treated on 5 consecutive days of weeks 0, 4, 8, 12 and 16 with epiBr. The remaining two groups were mock treated with the drug vehicle alone. Treatment started 1 week prior to infection and extended for 4 weeks after infection. Cats were observed for 20 weeks post-FIV infection. Infected cats had identical decreases in blood neutrophil and lymphocyte counts following, regardless of whether they were treated with epiBr or vehicle alone. The CD4/CD8 T-cell ratio was decreased following FIV exposure, but was significantly more decreased for the epiBr treated animals from week 2 post-infection onward. CD4+ T cells were decreased in FIV-infected cats treated with epiBr compared to their untreated cohort, while CD8+ T cells tended to be higher in treated animals. FIV infected cats that were treated with epiBr had over one-log higher virus loads at week 2 post-infection than non-epiBr treated cohorts. In spite of this enhanced initial viremia, the subsequent levels of virus in the blood were significantly lower in epiBr treated versus untreated animals. EpiBr treated cats had significantly higher FIV-p24 antibody responses than control cats receiving vehicle alone, although primary and secondary antibody responses to a T-cell dependent non-FIV antigen, keyhole limpet hemocyanin (KLH), were unaffected. EpiBr treatment significantly decreased the expected FIV-induced suppression of IL-12 p40 mRNA levels in peripheral blood mononuclear cells (PBMCs) observed at weeks 4, 5, 8, 9 and 16 post-infection, but had no influence on FIV-induced changes in IL-4, IL-6, IL-10, IFN-gamma, MIP-1alpha and RANTES.

Accelerated viraemia in cats vaccinated with fixed autologous FIV-infected cells.

We have vaccinated cats with fixed autologous FIV infected PBMC to determine whether autologous presentation of antigen is capable of inducing a protective immune response against homologous challenge. To this end autologous PBMC were infected with a FIV molecular clone (19k1). When infection was established, cells were inactivated by dialysis against paraformaldehyde. Upon vaccination, cats developed a virus specific immune response as measured by ELISA against the Gag protein of FIV. No antibodies against the envelope protein were detected with a peptide ELISA. Virus neutralizing antibodies however could be detected with a neutralization assay based on infection of CrFK cells, but not in an assay based on infection of primary T-cells. Although vaccination led to the induction of these virus-specific immune responses, vaccinated cats were not protected against homologous challenge but showed an accelerated viraemia upon infection. This was shown both by PCR and cell-associated viral load. The possible mechanisms underlying this observation are discussed in this paper.

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to bovine viral diarrhoea virus (BVDV) in cattle sera.

A microtitre ELISA has been established for the quantitation of antibodies to bovine viral diarrhoea virus (BVDV). Single dilutions of sera were assayed and units of antibody were calculated from a standard curve. In order to detect the maximum number of responding animals both IgG1 and IgG2 antibody should be assayed, although detection of IgG1 alone was nearly as effective. The ELISA was as sensitive as the virus neutralization test for detection of antibody; comparison of an ELISA that detected IgG1 plus IgG2 antibody to BVDV with the virus neutralization test gave a correlation coefficient (r) of 0.89 (P less than 0.001 for 95 compared sera). Although similar amounts of IgG1 and IgG2 antibodies were present in sera from both experimentally- and naturally-infected cattle, antibody to BVDV in colostrum and in the sera from young calves was predominantly IgG1. The number of adult cows with antibody was 40 out of 41 while 36 of 44 calves reared in a beef unit were found to have produced antibody by the time they were 31.5 weeks old, an indication of the high prevalence of BVDV in the cattle population.