Humoral and Cellular Immunity in Chromium Picolinate-Supplemented Lambs

The effects of oral supplementation of chromium picolinate (CrPic) on humoral and cellular immunity in sheep were investigated. Twenty-four male lambs divided into four treatments and received different dosages of CrPic: placebo (0), 0.250, 0.375, and 0.500 mg of chromium/animal/day during 84 days. The base ration was Panicum maximum cv Massai hay and concentrate. Blood samples were collected fortnightly for total and differential leukocyte counts. On days 28 and 56, the lambs were challenged with chicken ovalbumin I.M. Serum samples were collected on days 46 and 74 and subjected to an indirect enzyme-linked immunosorbent assay to measure IgG anti-ovalbumin. The cell-mediated immune response was determined by a delay-type hypersensitivity test using phytohemagglutinin. CrPic did not significantly affect humoral immunity in lambs but there was a negative effect on cellular immunity (P?<?0.05) as Cr supplementation increased. Therefore, the level of Cr supplementation for lambs must be better studied to address its effect on stressed animals or the possible toxic effects of Cr on the animal itself or its immune system.     

Cellular and Humoral Immunity: a Distinction in Antigenic Recognition

THERE is little or no humoral cross reactivity between the native and denatured forms of a protein antigen. Antibodies to native bovine ribonuclease do not bind ribonuclease oxidized with performic acid^1–3, indicating that antibodies can distinguish between two molecular conformations. There is no humoral cross reactivity between rabbit IgG and the product of reduction of all the disulphide bridges^4–6. Also there is essentially no serological cross reactivity between lysozyme and its reduced and S-carboxymethylated (CM-lysozyme) derivative^7–9.     

Rift Valley Fever Virus Seroprevalence in Human Rural Populations of Gabon

Background

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis caused by a phlebovirus and transmitted by Aedes mosquitoes. Humans can also be infected through direct contact with blood (aerosols) or tissues (placenta, stillborn) of infected animals. Although severe clinical cases can be observed, infection with RVF virus (RVFV) in humans is, in most cases, asymptomatic or causes a febrile illness without serious symptoms. In small ruminants RVFV mainly causes abortion and neonatal death. The distribution of RVFV has been well documented in many African countries, particularly in the north (Egypt, Sudan), east (Kenya, Tanzania, Somalia), west (Senegal, Mauritania) and south (South Africa), but also in the Indian Ocean (Madagascar, Mayotte) and the Arabian Peninsula. In contrast, the prevalence of RVFV has rarely been investigated in central African countries.

Methodology/Principal Findings

We therefore conducted a large serological survey of rural populations in Gabon, involving 4,323 individuals from 212 randomly selected villages (10.3% of all Gabonese villages). RVFV-specific IgG was found in a total of 145 individuals (3.3%) suggesting the wide circulation of Rift Valley fever virus in Gabon. The seroprevalence was significantly higher in the lakes region than in forest and savannas zones, with respective rates of 8.3%, 2.9% and 2.2%. In the lakes region, RVFV-specific IgG was significantly more prevalent in males than in females (respectively 12.8% and 3.8%) and the seroprevalence increased gradually with age in males but not in females.

Conclusions/Significance

Although RVFV was suggested to circulate at a relatively high level in Gabon, no outbreaks or even isolated cases have been documented in the country. The higher prevalence in the lakes region is likely to be driven by specific ecologic conditions favorable to certain mosquito vector species. Males may be more at risk of infection than females because they spend more time farming and hunting outside the villages, where they may be more exposed to mosquito bites and infected animals. Further investigations are needed to determine the putative sylvan cycle of RVFV, including the mosquito species and the reservoir role of wild animals in the viral maintenance cycle.     

Norovirus P Particle Efficiently Elicits Innate,Humoral and Cellular Immunity

Norovirus (NoV) P domain complexes, the 24 mer P particles and the P dimers, induced effective humoral immunity, but their role in the cellular immune responses remained unclear. We reported here a study on cellular immune responses of the two P domain complexes in comparison with the virus-like particle (VLP) of a GII.4 NoV (VA387) in mice. The P domain complexes induced significant central memory CD4⁺ T cell phenotypes (CD4⁺ CD44⁺ CD62L⁺ CCR7⁺) and activated polyclonal CD4⁺ T cells as shown by production of Interleukin (IL)-2, Interferon (IFN)-γ, and Tumor Necrosis Factor (TNF)-α. Most importantly, VA387-specific CD4⁺ T cell epitope induced a production of IFN-γ, indicating an antigen-specific CD4⁺ T cell response in P domain complex-immunized mice. Furthermore, P domain complexes efficiently induced bone marrow-derived dendritic cell (BMDC) maturation, evidenced by up-regulation of co-stimulatory and MHC class II molecules, as well as production of IL-12 and IL-1β. Finally, P domain complex-induced mature dendritic cells (DCs) elicited proliferation of specific CD4⁺ T cells targeting VA387 P domain. Overall, we conclude that the NoV P domain complexes are efficiently presented by DCs to elicit not only humoral but also cellular immune responses against NoVs. Since the P particle is highly effective for both humoral and cellular immune responses and easily produced in Escherichia coli (E. coli), it is a good choice of vaccine against NoVs and a vaccine platform against other diseases.     

High Prevalence of the Amphibian Chytrid Pathogen in Gabon

Amphibian chytridiomycosis is an infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd) that is implicated in the worldwide decline and extinction of amphibians. Africa has been proposed as a potential source for the global expansion of Bd, yet the distribution of Bd across the continent remains largely unexplored. Using quantitative polymerase chain reaction (qPCR), we screened for the presence of Bd in 166 adult anurans from two national parks in Gabon (Monts de Cristal and Ivindo). Bd was detected in 20 of the 42 species and was present at all three sites surveyed (two in Monts de Cristal, and one in Ivindo) with high prevalence (19.6%-36.0%). Both national parks were Bd-positive at all elevations and across habitat types, though no dead or dying frogs were encountered. To our knowledge, this study presents the first evidence of Bd in Gabon and the first record of infection for 19 of the 20 species that were Bd-positive. Documenting the distribution and virulence of Bd across Africa will be essential for understanding the dynamics of amphibian chytridiomycosis across the globe.     

Further Evidence for Involvement of Both Cell Mediated and Humoral Immunity in Generalized Vitiligo

Immunohistochemical and immunoserological evidence supports the involvement of both cell-mediated and humoral mechanisms in the pathogenesis of melanocyte destruction in vitiligo. Punch biopsies from depigmented vitiliginous skin (VS), normal-looking pigmented skin (PS), and marginal skin (MS) from patients with generalized vitiligo (n = 15) were labeled with K 1.2.58, OKM1 (CD11b), Leu 11b (CD16), Leu 19 (CD56), IFN-γreceptor, IL-2 receptor (CD25), IgG, IgM, C3c, and C3d MoAbs. In addition, in vitro effects of vitiligo sera (n = 13) on human newborn melanocytes (HMel) under different culture conditions were studied. The immunohistochemical findings showed absence of K 1.2.58+ epidermal melanocytes in VS and abnormal morphology in MS. In these areas, a few CD11b + cells in the dermis and epidermis could be detected but no significant numbers of CD16+ or CD56+ cells were seen among the mononuclear cellular infiltrate. IL-2 and IFN-γ receptors were clearly expressed by the cellular infiltrate. No significant deposition of complement or immunoglobulin was seen. The addition of vitiligo sera to HMel cultures induced a significant cellular proliferation. The stimulation of cell proliferation occurred regardless whether the sera were added alone or when preheated (56°C for 1 hr) and then supplemented with a complement source (P < 0.01 at 2%, P < 0.001 at 10%, and P < 0.01 at 20% for sera alone) (P > 0.05 at 2%, P < 0.05 at 10%, and P < 0.01 at 20% for decomplemented sera plus complement). In contrast, incubation of vitiligo sera together with normal lymphocytes with HMel significantly decreased the number of living melanocytes in a dose dependent manner, suggesting an antibody-dependent cellular cytotoxicity (ADCC) reaction (P < 0.01 at 2% and 10%, P < 0.001 at 20%). The presence of lymphocytic infiltrate at marginal skin with evidence for IL-2- and IFN-γ-receptor expression and the decrease in the number of living cells by ADCC-like mechanisms provide further support for an autoimmune pathogenesis in vitiligo.     

The High Prevalence of Low HDL-Cholesterol Levels and Dyslipidemia in Rural Populations in Northwestern China

Background

Dyslipidemia is a major health problem in China and an important modifiable cardiovascular disease (CVD) risk factor. This study aimed to describe the prevalence of dyslipidemia and low high density lipoprotein cholesterol (HDL-cholesterol) and associated risk factors among adults in rural northwest China.

Methods

In a cross-sectional analyses involving 2,980 adults aged >18 years, information on the demographics, cigarette smoking, alcohol consumption, education, and medical history was collected via face-to-face interviews. Blood samples were collected to determine total cholesterol (TC), low-density lipoprotein cholesterol (LDL-cholesterol), and HDL-cholesterol, and triglycerides (TG) levels.

Results

The prevalence of high TC, high LDL-cholesterol, low HDL-cholesterol, and high TG were 1.0%, 0.6%, 60.9%, and 13.7%, respectively. TC, LDL-cholesterol, and TG increased with age in females. Elevated TC was more common in females than in males. The prevalence of low HDL-cholesterol was 67.6% in males and 55.4% in females. Current smokers, those with less education, those who were overweight or obese, and those with large waist circumference were more likely to have low HDL-cholesterol (p<0.05). Multivariable regression showed that male gender showed an association with low HDL-cholesterol (OR 2.10, 95%CI 1.68–2.61), age ≥60 years (OR 0.80, 95% CI 0.64–0.99), BMI (BMI = 24–27.9, OR 1.27, 95%CI 1.04–1.54, p = 0.02 and BMI≥28, OR 1.56, 95%CI 1.10–2.20, p = 0.01) and enlarged waist circumference (OR 2.10, 95%CI 1.51–2.92). Non-alcohol drinker was associated with low HDL-cholesterol levels (OR 0.72, 95%CI 0.53–0.99, p = 0.04).

Conclusions

This study found that the prevalence of low HDL-cholesterol was 67.6% and 55.4% for males and females. Male gender, non-alcohol drinker, BMI and central obesity were important risk factors for low HDL-cholesterol in Chinese adults.     

Conserved receptor-binding domains of Lake Victoria marburgvirus and Zaire ebolavirus bind a common receptor

The GP(1,2) envelope glycoproteins (GP) of filoviruses (marburg- and ebolaviruses) mediate cell-surface attachment, membrane fusion, and entry into permissive cells. Here we show that a 151-amino acid fragment of the Lake Victoria marburgvirus GP1 subunit bound filovirus-permissive cell lines more efficiently than full-length GP1. An homologous 148-amino acid fragment of the Zaire ebolavirus GP1 subunit similarly bound the same cell lines more efficiently than a series of longer GP1 truncation variants. Neither the marburgvirus GP1 fragment nor that of ebolavirus bound a nonpermissive lymphocyte cell line. Both fragments specifically inhibited replication of infectious Zaire ebolavirus, as well as entry of retroviruses pseudotyped with either Lake Victoria marburgvirus or Zaire ebolavirus GP(1,2). These studies identify the receptor-binding domains of both viruses, indicate that these viruses utilize a common receptor, and suggest that a single small molecule or vaccine can be developed to inhibit infection of all filoviruses.     

Aerosol exposure to Zaire ebolavirus in three nonhuman primate species: differences in disease course and clinical pathology

There is little known concerning the disease caused by Zaire ebolavirus (ZEBOV) when inhaled, the likely route of exposure in a biological attack. Cynomolgus macaques, rhesus macaques, and African green monkeys were exposed to aerosolized ZEBOV to determine which species might be the most relevant model of the human disease. A petechial rash was noted on cynomolgus and rhesus macaques after fever onset but not on African green monkeys. Fever duration was shortest in rhesus macaques (62.7 ± 16.3 h) and longest in cynomolgus macaques (82.7 ± 22.3 h) and African green monkeys (88.4 ± 16.7 h). Virus was first detectable in the blood 3 days after challenge; the level of viremia was comparable among all three species. Hematological changes were noted in all three species, including decreases in lymphocyte and platelet counts. Increased blood coagulation times were most pronounced in African green monkeys. Clinical signs and time to death in all three species were comparable to what has been reported previously for each species after parenteral inoculation with ZEBOV. These data will be useful in selection of an animal model for efficacy studies.     

Cell Interactions in Humoral and Cell-mediated Immunity

THYMUS-derived lymphocytes (T-cells) play an important role in the initiation of both humoral and cell-mediated immunity^1–3. We have investigated whether the helper function and the cell-mediated killer function of lymphocyte populations are performed by the same cells, by assaying thymus-derived lymphocytes both for their capacity to cooperate in vitro with bone marrow-derived lymphocytes (B-cells) in the induction of plaque-forming cells and for their capacity to cause in vitro complement independent lysis of target cells.     

Glossina fusca group tsetse as vectors of cattle trypanosomiasis in Gabon and Zaire

1. The significance of Glossina fusca group tsetse flies as vectors of cattle trypanosomiasis was examined using biconical traps to survey tsetse populations at one site in Gabon and two sites in Zaire. 2. Mean trypanosome infection rates in G.tabaniformis Westwood over the study period ranged from a minimum of 8.9% at one site to a maximum of 17.7% at another. The mean infection rate in G.nashi Potts was 6.0%. 3. Up to 49% of bloodmeals of G.tabaniformis were from cattle. Trypanosome prevalence in cattle where G.tabaniformis appeared to be the main vector was 9.5% and 5.4% at the Mushie and OGAPROV ranches, respectively. 4. A highly significant positive correlation was found between tsetse challenge and trypanosome prevalence in N'Dama cattle across sites. Tsetse challenge was defined as the product of tsetse relative densities, trypanosome infection rates in the flies and the proportion of feeds taken by them from cattle. Thus, G.tabaniformis can be an important vector of pathogenic Trypanosoma species in cattle.     

A Novel HIV Vaccine Adjuvanted by IC31 Induces Robust and Persistent Humoral and Cellular Immunity

The HIV vaccine strategy that, to date, generated immune protection consisted of a prime-boost regimen using a canarypox vector and an HIV envelope protein with alum, as shown in the RV144 trial. Since the efficacy was weak, and previous HIV vaccine trials designed to generate antibody responses failed, we hypothesized that generation of T cell responses would result in improved protection. Thus, we tested the immunogenicity of a similar envelope-based vaccine using a mouse model, with two modifications: a clade C CN54gp140 HIV envelope protein was adjuvanted by the TLR9 agonist IC31®, and the viral vector was the vaccinia strain NYVAC-CN54 expressing HIV envelope gp120. The use of IC31® facilitated immunoglobulin isotype switching, leading to the production of Env-specific IgG2a, as compared to protein with alum alone. Boosting with NYVAC-CN54 resulted in the generation of more robust Th1 T cell responses. Moreover, gp140 prime with IC31® and alum followed by NYVAC-CN54 boost resulted in the formation and persistence of central and effector memory populations in the spleen and an effector memory population in the gut. Our data suggest that this regimen is promising and could improve the protection rate by eliciting strong and long-lasting humoral and cellular immune responses.     

Canine Distemper Virus DNA Vaccination Induces Humoral and Cellular Immunity and Protects against a Lethal Intracerebral Challenge

We have studied the immune responses to the two glycoproteins of the Morbillivirus canine distemper virus (CDV) after DNA vaccination of BALB/c mice. The plasmids coding for both CDV hemagglutinin (H) and fusion protein (F) induce high levels of antibodies which persist for more than 6 months. Intramuscular inoculation of the CDV DNA induces a predominantly immunoglobulin G2a (IgG2a) response (Th1 response), whereas gene gun immunization with CDV H evokes exclusively an IgG1 response (Th2 response). In contrast, the CDV F gene elicited a mixed, IgG1 and IgG2a response. Mice vaccinated (by gene gun) with either the CDV H or F DNA showed a class I-restricted cytotoxic lymphocyte response. Immunized mice challenged intracerebrally with a lethal dose of a neurovirulent strain of CDV were protected. However, approximately 30% of the mice vaccinated with the CDV F DNA became obese in the first 2 months following the challenge. This was not correlated with the serum antibody levels.Inoculation of plasmid DNA into muscle and the subsequent expression of the encoded protein have opened up new approaches in vaccination and gene therapy (for an extensive review see reference 25). Although initial studies used intramuscular (i.m.) inoculation to deliver the DNA, other routes have been shown to be equally or more efficient in inducing immune responses, which may be related to the types of antigen-presenting cells (APCs) which are involved (9). Recent observations suggest that after i.m. inoculation, muscle cells probably act as a reservoir for the foreign antigen, while the bone marrow cells seem to act as the APCs (8, 12, 26, 27). For DNA delivery to the skin, the APCs have not yet been identified but could well include cells of dendritic origin (21). Although both intradermal and i.m. DNA inoculations induce a strong Th1 response, inoculation of DNA precipitated onto gold beads and delivered by means of a gene gun favors a Th2 response (7). Whether this is due to the targeting of different APCs has not been determined.We have been studying the possibility of using DNA vaccination to protect against canine distemper virus (CDV). CDV is a member of the genus Morbillivirus, in the Paramyxoviridae family, and although this virus primarily infects dogs, the disease has also been described in several animal species both in nature and in captivity (10, 18, 22). The currently available live attenuated vaccine efficiently protects dogs once maternal antibodies have disappeared, but it is not sufficiently attenuated for certain other animal species in which a fatal infection may ensue (6). This has led to a problem in protecting members of rare animal species living in captivity.In the present study, we have expressed the two CDV glycoproteins, the attachment protein (hemagglutinin [H]) and the fusion protein (F), from plasmids driven by a cytomegalovirus (CMV) promoter. We show that i.m. and intradermal inoculation of the CDV H-encoding plasmid induces a Th1 response, whereas gene gun inoculation of the same plasmid induces a Th2-type response. In contrast, the CDV F gene administered with the gene gun elicited a mixed Th response. Mice immunized with either of the plasmids were protected against a lethal intracerebral (i.c.) infection.     

The Prevalence of Obesity and Its Determinants in Urban and Rural Aging Mexican Populations

LERMAN-GARBER, ISRAEL, ANTONIO R. VILLA, CRISTINA LLACA MARTINEZ, LETICIA CERVANTES TURRUBIATEZ, CARLOS A. AGUILAR SALINAS, VILLAGRA LUCY, BELIA WONG, JUAN C. LÓPEZ ALVARENGA, FRANCISCO GÓMEZ PÉREZ, AND LUIS MIGUEL GUTIERREZ ROBLEDO. The prevalence of obesity and its determinants in urban and rural older mexican populations. Obes Res. Objective: To determine the prevalence of obesity and its association to different variables in urban and rural older Mexican populations. Methods and Procedures: A cross-sectional study of three different Mexican communities. A total of 121 men and 223 women 60 years and older and 93 men and 180 women aged 35 to 59 years old were selected randomly for inclusion in the survey. A personal interview assessed demographic information, personal medical history and functional status and a 24-hour diet recall was obtained. The physical examination included anthropometric and blood pressure measurements. A fasting blood sample was obtained for measurements of lipids, insulin and glucose. Results: Obesity was highly prevalent in women, in individuals from the urban communities and diminished with advancing age. A BMI ≥30 kg/m² was observed in 23. 6% younger vs. 15. 6% older adult men (p = 0. 21) and 28. 4% younger vs. 19. 7% older adult women (p = 0. 06). Conclusions: The present survey confirms the high prevalence of obesity in the Mexican urban population that declines with advanced age. Studies in elderly population must consider the bias produced by increased early mortality in those individuals with a more unfavorable risk profile. The association of obesity with other variables was estimated using a stepwise multivariate logistic regression, increased insulin levels [Odds Ratio (OR) 1. 68, p = 0. 006] and living in an urban area (OR 5. 90, p <0. 007) were variables independently associated to obesity in adult older individuals. In the younger adults, obesity was associated with hypertension (OR 2. 74, p<0. 0009), higher insulin levels (OR 1. 31, p<0. 03) and central adiposity (OR 2. 97, p = 0. 05), these relationship were not observed with gender, distribution of food or alcohol intake or other coronary risk factors.     

Naturally Induced Humoral Immunity to West Nile Virus Infection in Raptors

West Nile virus (WNV) infection can be fatal to many bird species, including numerous raptors, though population- and ecosystem-level impacts following introduction of the virus to North America have been difficult to document. Raptors occupy a diverse array of habitats worldwide and are important to ecosystems for their role as opportunistic predators. We documented initial (primary) WNV infection and then regularly measured WNV-specific neutralizing antibody titers in 16 resident raptors of seven species, plus one turkey vulture. Most individuals were initially infected and seroconverted between July and September of 2003, though three birds remained seronegative until summer 2006. Many of these birds became clinically ill upon primary infection, with clinical signs ranging from loss of appetite to moderate neurological disease. Naturally induced WNV neutralizing antibody titers remained essentially unchanged in some birds, while eight individuals experienced secondary rises in titer presumably due to additional exposures at 1, 2, or 3 years following primary infection. No birds experienced clinical signs surrounding or following the time of secondary exposure, and therefore antibodies were considered protective. Results of this study have implications for transmission dynamics of WNV and health of raptor populations, as well as the interpretation of serologic data from free-ranging and captive birds. Antibodies in raptors surviving WNV may persist for multiple years and protect against potential adverse effects of subsequent exposures.     

Field-Evaluation of a New Lateral Flow Assay for Detection of Cellular and Humoral Immunity against Mycobacterium leprae

Background

Field-applicable tests detecting asymptomatic Mycobacterium leprae (M. leprae) infection or predicting progression to leprosy, are urgently required. Since the outcome of M. leprae infection is determined by cellular- and humoral immunity, we aim to develop diagnostic tests detecting pro-/anti-inflammatory and regulatory cytokines as well as antibodies against M. leprae. Previously, we developed lateral flow assays (LFA) for detection of cytokines and anti-PGL-I antibodies. Here we evaluate progress of newly developed LFAs for applications in resource-poor settings.

Methods

The combined diagnostic value of IP-10, IL-10 and anti-PGL-I antibodies was tested using M. leprae-stimulated blood of leprosy patients and endemic controls (EC). For reduction of the overall test-to-result time the minimal whole blood assay time required to detect distinctive responses was investigated. To accommodate LFAs for field settings, dry-format LFAs for IP-10 and anti-PGL-I antibodies were developed allowing storage and shipment at ambient temperatures. Additionally, a multiplex LFA-format was applied for simultaneous detection of anti-PGL-I antibodies and IP-10. For improved sensitivity and quantitation upconverting phosphor (UCP) reporter technology was applied in all LFAs.

Results

Single and multiplex UCP-LFAs correlated well with ELISAs. The performance of dry reagent assays and portable, lightweight UCP-LF strip readers indicated excellent field-robustness. Notably, detection of IP-10 levels in stimulated samples allowed a reduction of the whole blood assay time from 24 h to 6 h. Moreover, IP-10/IL-10 ratios in unstimulated plasma differed significantly between patients and EC, indicating the feasibility to identify M. leprae infection in endemic areas.

Conclusions

Dry-format UCP-LFAs are low-tech, robust assays allowing detection of relevant cytokines and antibodies in response to M. leprae in the field. The high levels of IP-10 and the required shorter whole blood assay time, render this cytokine useful to discriminate between leprosy patients and EC.     

Alphavirus Replicon Particles Expressing TRP-2 Provide Potent Therapeutic Effect on Melanoma through Activation of Humoral and Cellular Immunity

Background

Malignant melanoma is the deadliest form of skin cancer and is refractory to conventional chemotherapy and radiotherapy. Therefore alternative approaches to treat this disease, such as immunotherapy, are needed. Melanoma vaccine design has mainly focused on targeting CD8⁺ T cells. Activation of effector CD8⁺ T cells has been achieved in patients, but provided limited clinical benefit, due to immune-escape mechanisms established by advanced tumors. We have previously shown that alphavirus-based virus-like replicon particles (VRP) simultaneously activate strong cellular and humoral immunity against the weakly immunogenic melanoma differentiation antigen (MDA) tyrosinase. Here we further investigate the antitumor effect and the immune mechanisms of VRP encoding different MDAs.

Methodology/Principal Findings

VRP encoding different MDAs were screened for their ability to prevent the growth of the B16 mouse transplantable melanoma. The immunologic mechanisms of efficacy were investigated for the most effective vaccine identified, focusing on CD8⁺ T cells and humoral responses. To this end, ex vivo immune assays and transgenic mice lacking specific immune effector functions were used. The studies identified a potent therapeutic VRP vaccine, encoding tyrosinase related protein 2 (TRP-2), which provided a durable anti-tumor effect. The efficacy of VRP-TRP2 relies on a novel immune mechanism of action requiring the activation of both IgG and CD8⁺ T cell effector responses, and depends on signaling through activating Fcγ receptors.

Conclusions/Significance

This study identifies a VRP-based vaccine able to elicit humoral immunity against TRP-2, which plays a role in melanoma immunotherapy and synergizes with tumor-specific CD8⁺ T cell responses. These findings will aid in the rational design of future immunotherapy clinical trials.     

Implication of PMLIV in Both Intrinsic and Innate Immunity

PML/TRIM19, the organizer of nuclear bodies (NBs), has been implicated in the antiviral response to diverse RNA and DNA viruses. Several PML isoforms generated from a single PML gene by alternative splicing, share the same N-terminal region containing the RBCC/tripartite motif but differ in their C-terminal sequences. Recent studies of all the PML isoforms reveal the specific functions of each. The knockout of PML renders mice more sensitive to vesicular stomatitis virus (VSV). Here we report that among PML isoforms (PMLI to PMLVIIb), only PMLIII and PMLIV confer resistance to VSV. Unlike PMLIII, whose anti-VSV activity is IFN-independent, PMLIV can act at two stages: it confers viral resistance directly in an IFN-independent manner and also specifically enhances IFN-β production via a higher activation of IRF3, thus protecting yet uninfected cells from oncoming infection. PMLIV SUMOylation is required for both activities. This demonstrates for the first time that PMLIV is implicated in innate immune response through enhanced IFN-β synthesis. Depletion of IRF3 further demonstrates the dual activity of PMLIV, since it abrogated PMLIV-induced IFN synthesis but not PMLIV-induced inhibition of viral proteins. Mechanistically, PMLIV enhances IFN-β synthesis by regulating the cellular distribution of Pin1 (peptidyl-prolyl cis/trans isomerase), inducing its recruitment to PML NBs where both proteins colocalize. The interaction of SUMOylated PMLIV with endogenous Pin1 and its recruitment within PML NBs prevents the degradation of activated IRF3, and thus potentiates IRF3-dependent production of IFN-β. Whereas the intrinsic antiviral activity of PMLIV is specific to VSV, its effect on IFN-β synthesis is much broader, since it affects a key actor of innate immune pathways. Our results show that, in addition to its intrinsic anti-VSV activity, PMLIV positively regulates IFN-β synthesis in response to different inducers, thus adding PML/TRIM19 to the growing list of TRIM proteins implicated in both intrinsic and innate immunity.