Serum Neutralizing Antibody Titers Research Articles

A Live Attenuated Severe Acute Respiratory Syndrome Coronavirus Is Immunogenic and Efficacious in Golden Syrian Hamsters

The immunogenicity and protective efficacy of a live attenuated vaccine consisting of a recombinant severe acute respiratory syndrome (SARS) coronavirus lacking the E gene (rSARS-CoV-DeltaE) were studied using hamsters. Hamsters immunized with rSARS-CoV-DeltaE developed high serum-neutralizing antibody titers and were protected from replication of homologous (SARS-CoV Urbani) and heterologous (GD03) SARS-CoV in the upper and lower respiratory tract. rSARS-CoV-DeltaE-immunized hamsters remained active following wild-type virus challenge, while mock-immunized hamsters displayed decreased activity. Despite being attenuated in replication in the respiratory tract, rSARS-CoV-DeltaE is an immunogenic and efficacious vaccine in hamsters.

Protection of Rabbits against Challenge with Rabbit Papillomaviruses by Immunization with the N Terminus of Human Papillomavirus Type 16 Minor Capsid Antigen L2

Current L1 virus-like particle (VLP) vaccines provide type-restricted protection against a small subset of the human papillomavirus (HPV) genotypes associated with cervical cancer, necessitating continued cytologic screening of vaccinees. Cervical cancer is most problematic in countries that lack the resources for screening or highly multivalent HPV VLP vaccines, suggesting the need for a low-cost, broadly protective vaccinogen. Here, N-terminal L2 polypeptides comprising residues 1 to 88 or 11 to 200 derived from HPV16, bovine papillomavirus type 1 (BPV1), or cottontail rabbit papillomavirus (CRPV) were produced in bacteria. Rabbits were immunized with these N-terminal L2 polypeptides and concurrently challenged with CRPV and rabbit oral papillomavirus (ROPV). Vaccination with either N-terminal L2 polypeptides of CRPV effectively protected rabbits from CRPV challenge but not from papillomas induced by cutaneous challenge with CRPV genomic DNA. Furthermore, papillomas induced by CRPV genomic DNA deficient for L2 expression grew at the same rate as those induced by wild-type CRPV genomic DNA, further suggesting that the L2 polypeptide vaccines lack therapeutic activity. Neutralizing serum antibody titers of >15 correlated with protection (P < 0.001), a finding consistent with neutralizing antibody-mediated protection. Surprisingly, a remarkable degree of protection against heterologous papillomavirus types was observed after vaccination with N-terminal L2 polypeptides. Notably, vaccination with HPV16 L2 11-200 protected against cutaneous and mucosal challenge with CRPV and ROPV, respectively, papillomaviruses that are evolutionarily divergent from HPV16. Further, vaccination with HPV16 L2 11-200 generates broadly cross-neutralizing serum antibody, suggesting the potential of L2 as a second-generation preventive HPV vaccine antigen.

Immune responses to foot-and-mouth disease virus in pig farms after the 1997 outbreak in Taiwan

This paper reports on a retrospective study of the antibody responses to structural and non-structural proteins of FMD virus O Taiwan 97 in six pig herds in Taiwan in the year after the 1997 Taiwanese FMD outbreak. All herds were vaccinated against FMD after the outbreak as part of the countrywide control program. Three of the herds had confirmed FMD infections (herds N, O and P) and three herds remained non-infected (herds K, L and M). The serum neutralizing antibody titers and the non-structural protein ELISA (NSP) antibody responses in sows and 1-month-old pigs in the infected herds were higher than in the non-infected herds, but over time a number of positive NSP reactors were detected. From the serological studies and the herd monitoring and investigations it was considered that the FMD NSP positive reactors may not have constituted a true reservoir of FMD virus infection especially in herds where susceptible pigs were no longer present post-exposure or post-vaccination. Pigs vaccinated with an unpurified FMD type O vaccines being used at that time also showed false positive responses for NSP antibodies.

Efficient priming against classical swine fever with a safe glycoprotein E2 expressing Orf virus recombinant (ORFV VrV-E2)

An increasing demand in livestock animal husbandry for intervention or emergency vaccination strategies requires a rapid onset of protection linked to prevention of infectious agent spread. Using the new recombinant parapoxvirus (PPV) Orf virus (ORFV) as a vaccine expressing the CSFV E2 glycoprotein we demonstrate that a single intra-muscular application confers solid protection. In the prime only concept, multi-site application of the vector vaccine turned out to be superior to single-site application as no pyrexia occurred after virulent CSFV challenge and CSFV neutralizing serum antibodies regularly were detectable before challenge. Vector virus vaccinated swine were able to cope with the lymphocyte and in particular B-cell depression in peripheral blood after challenge showing no clinical signs and no viremia. Early after challenge CSFV-specific IFN gamma production (IFN-gamma) and high neutralizing serum antibody titers clearly differentiated naïve from vaccinated and protected animals. After CSFV challenge neutralizing serum antibodies titers in vector vaccinated swine were significantly higher than those in sera from live attenuated vaccine primed animals. Horizontal challenge virus transmission was prevented under strict sentinel isolation before mingling but not in next-door stables separated by a wooden barrier at the day of challenge. The presence of CSFV-specific pre-challenge serum antibodies although in low titers is a good prognostic parameter for solid protection after ORFV vector vaccination even when a significant CSFV-specific IFN-gamma production was not detectable before challenge. A heterologous prime-boost regimen as a combination of prime with baculovirus-expressed glycoprotein E2 followed by boost with the parapoxvirus vector turned out to be a better immune stimulant than a homologous prime/boost with the modified live CSFV vaccine. A similar beneficial effect became evident when the challenge infection mimicked the booster vaccination after a single PPV vector prime.

SEROLOGIC RESPONSE TO A CANARYPOX-VECTORED CANINE DISTEMPER VIRUS VACCINE IN THE GIANT PANDA (AILUROPODA MELANOLEUCA)

The giant panda (Ailuropoda melanoleuca) is known to be susceptible to natural infection with canine distemper virus (CDV). Vaccination of giant pandas with conventional modified live CDV vaccines has been avoided due to the numerous carnivore species known to have become infected with CDV after vaccination. Serum-neutralizing antibodies to CDV were measured after s.c. and i.m. annual vaccination with a canarypox-vectored recombinant CDV vaccine in an adult male and female giant panda over the period of 2 yr. The vaccine proved to be safe, and serum-neutralizing antibody titers interpreted as protective against CDV disease were measured in each animal.

Human metapneumovirus: Enhanced pulmonary disease in cotton rats immunized with formalin-inactivated virus vaccine and challenged

Cotton rats (Sigmodon hispidus) are susceptible to the recently discovered human metapneumovirus (hMPV), an agent closely related to human respiratory syncytial virus. Since certain respiratory syncytial virus vaccines can induce enhanced disease upon viral challenge, we have done similar experiments with hMPV in cotton rats. Young adult cotton rats were vaccinated with a formalin-inactivated preparation of hMPV strain C-85473, or with a mock preparation of the vaccine on day 0 and again on day 28. All animals were challenged intranasally on day 49 with 10(7) TCID50 of the same hMPV strain. Animals were sacrificed on days 4, 7, and 10 post-challenge and lungs were removed for viral quantitation, histopathology, and cytokine mRNA expression analysis (interferon-gamma (IFN-gamma) and interleukin-4 (IL-4)). Although the vaccinated animals showed almost complete protection from viral replication in the lungs (<10(2.0) TCID50 per gram), there was a dramatic increase in the lung pathology, particularly the interstitial pneumonitis and alveolitis with elevated serum neutralizing antibody titer prior to challenge. Cytokine profiles were distinctive from those observed during primary infection and re-infection. The data raise safety concerns for hMPV vaccine preparations.

Vaccination of Healthy Volunteers with Human Papillomavirus Type 16 L2E7E6 Fusion Protein Induces Serum Antibody that Neutralizes across Papillomavirus Species

Oncogenic human papillomavirus (HPV) infection is a necessary cause of cervical cancer. Therefore, vaccination to prevent or eliminate HPV infection could reduce the incidence of cervical cancer. A fusion protein comprising HPV16 L2, E6, and E7 is a candidate combination preventive and therapeutic HPV vaccine. The L1- and L2-specific and neutralizing serum antibody titers and peripheral blood mononucleocyte antigen-specific proliferative responses generated by vaccination thrice at monthly intervals with HPV16 L2E7E6 were compared in two studies: a phase I randomized double-blind placebo controlled dose escalation trial in 40 healthy volunteers and a phase II trial of HPV16 L2E7E6 at the maximum dose in 29 women with high-grade anogenital intraepithelial neoplasia (AGIN). Vaccination of healthy volunteers induced L2-specific serum antibodies that were detected 1 month after the final vaccination (P(binomial) < 0.001). There was a significant trend to seroconversion for HPV16 and HPV18 neutralizing antibodies with increasing vaccine dose (P = 0.006 and P = 0.03, respectively). Seroconversion for HPV18 neutralizing antibodies showed a significant positive trend with increasing dose (P = 0.03) and was associated with seroconversion for HPV16 neutralizing antibodies (P(exact) = 0.04). The antigen-specific proliferative response of vaccinated healthy volunteers also showed a significant trend with increasing vaccine dose (P = 0.04). However, AGIN patients responded less effectively to vaccination than healthy patients for induction of HPV16 L2-specific antibody (P < 0.001) and proliferative responses (P < 0.001). Vaccination of healthy volunteers thrice with 533-mug HPV16 L2E7E6 at monthly intervals induced L2-specific serum antibodies that neutralized across papillomavirus species. Responses in AGIN patients were infrequent.

Membrane embedded HIV-1 envelope on the surface of a virus-like particle elicits broader immune responses than soluble envelopes

Virally regulated HIV-1 particles were expressed from DNA plasmids encoding Gag, protease, reverse transcriptase, Vpu, Tat, Rev, and Env. The sequences for integrase, Vpr, Vif, Nef, and the long terminal repeats (LTRs) were deleted. Mutations were engineered into the VLP genome to produce particles deficient in activities associated with viral reverse transcriptase, RNase H, and RNA packaging. Each plasmid efficiently secreted particles from primate cells in vitro and particles were purified from the supernatants and used as immunogens. Mice (BALB/c) were vaccinated intranasally (day 1 and weeks 3 and 6) with purified VLPs and the elicited immunity was compared to particles without Env (Gag p55), to soluble monomeric Env gp120, or to soluble trimerized Env gp140. Only mice vaccinated with VLPs had robust anti-Env cellular immunity. In contrast, all mice had high titer anti-Env serum antibody (IgG). However, VLP-vaccinated mice had antisera that detected a broader number of linear Env peptides, had anti-Env mucosal IgA and IgG, as well as higher titers of serum neutralizing antibodies. VLPs elicited high titer antibodies that recognized linear regions in V4-C5 and the ectodomain of gp41, but did not recognize V3. These lentiviral VLPs are effective mucosal immunogens that elicit broader immunity against Env determinants in both the systemic and mucosal immune compartments than soluble forms of Env.

Serum Neutralizing Antibody to the Alpha Toxin of Clostridium perfringens type A in Dairy Calves Fed Colostrum from Immunized Dams

The goal of this study was to determine if immunization of pregnant dairy cows and heifers with a commercially available vaccine affected the serum neutralizing antibody titer to alpha toxin (AbAT) in their colostrum-fed calves.

The Live Attenuated Dengue Serotype 1 Vaccine rDEN1Δ30 is Safe and Highly Immunogenic in Healthy Adult Volunteers

Background: The live attenuated DEN1 vaccine candidate virus rDEN1Δ30 has been evaluated in preclinical animal models and found to be attenuated and immunogenic. These promising preclinical studies have identified rDEN1Δ30 as a candidate DEN1 vaccine virus for further testing in a human Phase I clinical trial. Methods: rDEN1Δ30 at a dose of 103 pfu was administered as a single inoculation to twenty healthy adult volunteers. Eight additional volunteers received placebo. Volunteers were monitored closely for adverse events and serum was collected on study days 0, 28, 42, and 180 for determination of neutralizing antibody titer. Results: The vaccine was well tolerated by the vaccinees. The most common adverse events observed were a transient asymptomatic rash in 40% of vaccinees and a mild neutropenia in 45% of vaccinees. No vaccinee developed a dengue-like illness. The vaccine was highly infectious and immunogenic with 95% of vaccinees developing a ? 4-fold rise in serum neutralizing antibody titer against DEN1 that persisted throughout the six month duration of the trial. Conclusions: The rDEN1Δ30 vaccine is safe and induced a potent and durable antibody response against DEN1. It is a promising vaccine candidate for inclusion in a tetravalent dengue vaccine formulation.

A monoclonal antibody-based competitive enzyme-linked immunosorbent assay for detecting antibody production against avian reovirus protein σA

An assay protocol based on a monoclonal antibody-based competitive enzyme-linked immunosorbent assay (MAb-based c-ELISA) for detection of antibody against avian reovirus protein σA in chicken is described. After the conditions for MAb-based c-ELISA had been optimized, sera collected from birds that received live and inactivated avian reovirus vaccines in different combinations were tested for antibody response against virus protein σA. The results show a high level of antibody against σA was in both vaccinated specific pathogenic free (SPF) and vaccinated commercially reared birds as long as one of the vaccines administered was in an inactivated form. The high level of antibody production is indicated by a high percentage inhibition (PI) values in the sera of the birds; but no antibody production was found in birds which received live vaccine only, as indicated by the low PI values. In serum samples from SPF birds receiving vaccines that include an inactivated form of the vaccine, there is a good correlation between the PI values and serum neutralizing antibody (SN) titers. Again, this correlation was not observed in birds that received only live vaccine. The PI values of commercially reared birds receiving inactivated vaccine were significantly different from those of the mock-treated birds, but this was not the case when the birds received only live vaccine. Taken together, the results suggest that MAb-based c-ELISA may provide an alternative choice for determining the immune status of a vaccinated chicken flock as long as one of the vaccines used was inactivated, and thus would allow a more precise way to predict the appropriate time for vaccination.

Effects of the potency and composition of the multivalent human-bovine (WC3) reassortant rotavirus vaccine on efficacy, safety and immunogenicity in healthy infants

Background Rotavirus gastroenteritis, which causes substantial infant mortality and morbidity worldwide, is a vaccine-preventable disease. The purpose of this study was to evaluate different compositions and potencies (vaccine virus titers) of a live multivalent human-bovine (WC3) reassortant rotavirus vaccine in order to select the potency and composition of the vaccine for further development. Methods The efficacy, safety, and immunogenicity of a G1, G2, G3, G4, and P1A pentavalent composition at three different potencies, a G1, G2, G3, G4 quadrivalent composition, and a P1A monovalent composition of an oral human-bovine (WC3) reassortant rotavirus vaccine were compared in a blinded, placebo-controlled trial conducted between 1998 and 2001 enrolling 1946 healthy Finnish infants 2–8 months of age. Results All potencies of the pentavalent and quadrivalent vaccines were efficacious (58–74%) against wild-type rotavirus gastroenteritis of any severity and 100% protective against severe rotavirus disease caused by vaccine G-serotypes through the first rotavirus season post-vaccination. The monovalent P1A vaccine was 53% efficacious against moderate-and-severe rotavirus gastroenteritis. Protection against rotavirus gastroenteritis of any severity was demonstrated through two and three rotavirus seasons for all vaccine compositions. After the third dose, the percentage of infants with ≥3-fold rise in baseline serum neutralizing antibody titers against G1 ranged from 62% to 86% for recipients of the pentavalent vaccine, depending on the potency. The incidence of fever, irritability, vomiting, and diarrhea did not significantly differ between vaccine and placebo groups. A 7-month-old male developed intussusception 9 days after the first dose of the low-potency pentavalent vaccine. Conclusions Based on the results of this trial, a pentavalent composition (G1, G2, G3, G4, and P1A) of human-bovine (WC3) reassortant rotavirus vaccine with a potency similar to that of the middle-potency pentavalent vaccine (∼8 × 10 6 plaque-forming units/dose) was selected for further development.

Immunogenicity and efficacy of an in-house developed cell-culture derived veterinarian rabies vaccine

The efficiency of an inactivated tissue culture rabies vaccine produced on BHK-21 cells, according to an in-house developed process, was evaluated and compared to a commercial cell-tissue culture vaccine (Rabisin). Fifteen experimental dogs from local common breed were duly conditioned during a quarantine period, then vaccinated via the subcutaneous route with 1 ml of either the tissue culture vaccine developed in-house or the commercial vaccine Rabisin. The immune response of each dog was monitored for 162 days. Serum-neutralizing antibodies titers to rabies virus were determined by the rapid fluorescent focus inhibition test (RFFIT) which confirmed the strong response of dogs to both vaccines except one dog in the Rabisin group. The dogs were then challenged in the masseter muscle with a rabies street virus of canine origin. All vaccinated dogs except the single dog in the Rabisin group that failed to respond to the vaccine, survived the challenge. In contrast, 80% of animals in the control non-vaccinated group, developed rabies and died. A field vaccine trial was also conducted: 1000 local dogs living in field conditions received one subcutaneous dose of the locally developed vaccine. Serum neutralizing antibody titers to rabies virus was determined by RFFIT at days 0, 60 and 360. Mean rabies neutralizing antibody titers were equal to 0.786, 3.73 and 1.55 IU/ml, respectively. The percentage of dogs with a neutralizing rabies antibody titer higher than the 0.5 IU/ml mandated WHO threshold, was 30%, 91.4% and 87.5% at day 0, 2 months and 1 year post-vaccination, respectively. These data demonstrate the efficiency of the in-house developed vaccine produced on BHK-21 cells in both experimental and field conditions and support its use in dog mass vaccination campaigns.

Immune responses to AAV in a phase I study for Canavan disease

Canavan disease is a rare leukodystrophy with no current treatment. rAAV-ASPA has been developed for gene delivery to the central nervous system (CNS) for Canavan disease. This study represents the first use of a viral vector in an attempt to ameliorate a neurodegenerative disorder. Subjects received intracranial infusions via six cranial burr holes. Adeno-associated virus, serotype 2 (AAV2), mediated intraparenchymal delivery of the human aspartoacylase cDNA at a maximum dose of 1 x 10(12) vector genomes per subject. The immune response and safety profiles were monitored in the follow-up of ten subjects. Following rAAV2 administration, we found no evidence of AAV2 neutralizing antibody titers in serum for the majority of subjects tested (7/10). In a subset (3/10) of subjects, low to moderately high levels of AAV2 neutralizing antibody with respect to baseline were detected. In all subjects, there were minimal systemic signs of inflammation or immune stimulation. In subjects with catheter access to the brain lateral ventricle, cerebrospinal fluid was examined and there was a complete absence of neutralizing antibody titers with no overt signs of brain inflammation. rAAV2 vector administration to the human CNS appears well tolerated. The low levels of immune response to AAV2 detected in 3/10 subjects in this study suggest at this dose and with intraparenchymal administration this approach is relatively safe. Long-term monitoring of subjects and expansion to phase II/III will be necessary in order to make definitive statements on safety and efficacy.

785. A Novel Adeno Associated Virus Vector That Efficiently Transduces Airway Epithelium In Vivo and Can Be Re-Administered

Top of pageAbstract Airway|[ndash]|directed gene transfer has emerged as a promising approach for the treatment of cystic fibrosis and |[alpha]|-1-antitrypsin deficiency (AAT). It will be important to re-administer the vector for treatment of these chronic disorders. We have shown previously that AAV2/9 can efficiently target and transduce the murine upper and lower airways in vivo. As such we studied the performance of AAV2/9 in the setting of pre-existing immunity to homologous vector. C57Bl/6 mice were inoculated intratracheally with a single dose (1E+11 genome copies) of either AAV2/9 or AAV2/5 expressing AAT. We found that AAV2/9-mediated AAT expression was relatively stable for the duration of the experiment (9 months) and at the peak of gene expression was 60-fold higher than that of AAV2/5. Within two weeks of vector administration, high levels (>1:2560) of serum|[ndash]|circulating neutralizing antibodies (NAB) were observed in both AAV2/9 and AAV2/5 treated mice. Mice were divided into groups and designated groups were subjected to a second instillation of the same vector serotype expressing a different transgene (nLacZ) at specific time points after delivery of the AAV2/9- or AAV2/5|[ndash]| AAT vectors. Mice were sacrificed 21 days following the AAV|[ndash]| nLacZ vector instillation and the lung and nose processed for nLacZ expression. The serum NAB titers in the AAV2/9 treatment group remained high (average of 1:2560) up to day 112 and decreased to |[sim]|1:640 by day 217. Interestingly, we found that AAV2/9 was able to circumvent the AAV2/9-specific NABs, resulting in nLacZ gene transfer levels in nasal and lung airways similar to that of age-matched naive mice at all time points. In AAV2/5-treated mice, no transduced cells were seen in either the nasal or lung airways over a broad range of serum|[ndash]|circulating NAB titers (1:56000 to 1:1280). Some level of gene transfer was achieved with AAV2/5-nLacZ when administered 196 days after the AAT vector which was when serum NAB declined to 1:320|[ndash]|1:160. To explain why AAV2/9 can efficiently transduce the lung airway epithelium in the presence of high titer serum|[ndash]| circulating NAB, the bronchoalveolar lavage fluid (BALF) isolated from mice at the first time point (day 49) and at the end of the experiment (day 217) was analyzed for AAV-specific NABs. We did not observe any NAB titer, IgG or IgA responses to AAV2/9 vector. In contrast, when BALF from AAV2/5 treated mice was analyzed, NAB titers ranged from 1:160 to 1:1280, vector IgG responses from 1:100 to 1:12800 and vector IgA responses from 1:100|[ndash]|1:1600. Our results suggest that AAV2/9 is an excellent candidate for clinical applications that require long term transgene expression. We show that AAV2/9 can be re-administered to lung with out diminution of gene transfer efficiency while AAV2/5 can not. This finding further supports the development of AAV2/9 for use in clinical applications for chronic diseases in which vector re-administration will be necessary.

Identification of Herds with Cattle Persistently Infected with Bovine Viral Diarrhea Virus by Virological Evaluation of Three Calves

For the identification of herds with cattle persistently infected (PI) with bovine viral diarrhea virus, 1,272 animals from 20 herds were subjected to serum neutralizing (SN) test using the Nose strain and virus isolation. Eighteen PI cattle were detected from 5 herds. On the phylogenetic tree based on the nucleotide sequences of the 5' untranslated region, the isolates from the PI cattle were classified into genotypes-1a or -1b. Of 3 unvaccinated calves aged 6 to 12 months selected from each herd, the probabilities of obtaining 2 or more non-PI cattle with SN antibody titers of 64 or more (P(SN)), one or more PI cattle (P(VI)), and either of the conditions (P(Total)) were calculated using the hypergeometric probability model. P(Total) for the 5 herds with PI cattle was 1.000. P(SN) for 3 herds with many PI cattle within the selected age group was as low as 0.500 or less, and P(VI) was as high as 0.886 or more. P(SN) in the 2 other herds with few PI cattle was 1.000, and P(VI) was as low as 0.375 or less. P(Total) in 13 of 15 herds without PI cattle was 0.000, and was 0.714 or 0.774 for the 2 other herds. These results suggest that herds with PI cattle can be predicted with high accuracy when both SN test and virus isolation are performed on only 3 unvaccinated calves aged 6 to 12 months selected from a herd.

Immune responses to repetitive adenovirus-mediated gene transfer and restoration of gene expression by cyclophosphamide or etoposide

Background. One major concern about adenoviral vectors for repetitive gene delivery is the induction of an immune response to the vector, thus impeding effective gene transduction. Methods. To assess the immune response to the adenoviral vector, repetitive gene dosing was performed into rhesus monkey cervix and C3H mouse skin using the adenoviral vector carrying the lacZ gene. Three repetitive intracervical injections of adenovirus- lacZ were done in the rhesus monkey at the intervals of 4 weeks. Gene expression on the second and third injection was completely suppressed. Results. Anti-adenovirus IgG levels and neutralizing antibody titers in the rhesus monkey significantly increased after the first injection of adenovirus. In the C3H mouse, neutralizing antibody titers significantly increased after the first injection of adenovirus- lacZ at more than 10 8 plaque-forming unit (PFU). The repetitive expression of lacZ gene in the mouse skin markedly decreased when the second injection is done more than 2 weeks after the first injection. Chronic low-dose treatment with cyclophosphamide or etoposide markedly suppressed neutralizing antibody titers in the mouse serum and restored the gene expression in the mouse skin on the second and third injection. Conclusions. It is suggested that repetitive gene expression by adenovirus-mediated transfer may be reduced by circulating neutralizing antibodies and could be restored by chronic low-dose treatment with cyclophosphamide or etoposide.

Characterization of protection from systemic infection and disease by use of a modified-live noncytopathic bovine viral diarrhea virus type 1 vaccine in experimentally infected calves

To evaluate protection against systemic infection and clinical disease provided by use of a modified-live noncytopathic bovine viral diarrhea virus (BVDV) type 1 vaccine in calves challenged with NY-1 BVDV. 10 calves, 5 to 7 months of age. Calves were allocated (n = 5/group) to be nonvaccinated or vaccinated SC on day 0 with BVDV type 1 (WRL strain). Calves in both groups were challenged intranasally with NY-1 BVDV on day 21. Calves' rectal temperatures and clinical signs of disease were recorded daily, total and differential WBC and platelet counts were performed, and serum neutralizing antibody titers against NY-1 BVDV were determined. Histologic examinations and immunohistochemical analyses to detect gross lesions and distribution of viral antigens, respectively, were performed. After challenge exposure to NY-1 BVDV, nonvaccinated calves developed high rectal temperatures, increased respiratory rates, viremia, leukopenia, lymphopenia, and infection of the thymus. Vaccinated calves did not develop high rectal temperatures or clinical signs of respiratory tract disease. Vaccinated calves appeared to be protected against systemic replication of virus in that they did not develop leukopenia, lymphopenia, viremia, or infection of target organs, and infectious virus was not detected in peripheral blood mononuclear cells or the thymus. The modified-live BVDV vaccine protected calves against systemic infection and disease after experimental challenge exposure with NY-1 BVDV. The vaccine protected calves against infection and viremia and prevented infection of target lymphoid cells.

Improvement of herpetic stromal keratitis with fumaric acid derivate is associated with systemic induction of T helper 2 cytokines

Fumaric acid derivates have been shown to stimulate T helper-2-cytokines (interleukin (IL)-4, -5) without affecting the T-helper-1-cytokine (IL-2, interferon (IFN)-gamma)-response. Herein, the influence of systemic treatment with the fumaric acid derivate dimethylfumarate (DMF) on the secretion of T helper-cytokines and the development of HSV-1 stromal keratitis (HSK) was studied in mice. The corneas from BALB/c mice were infected with 10(5) PFU of HSV-1 (KOS strain). While one group of mice was treated intraperitoneally with PBS, another group of mice received DMF at 15 mg/kg of body weight. Expression of IL-2, -4, -10 and IFN-gamma was analysed in HSV-1 activated lymphocytes by ELISA. The severity of epithelial and stromal herpetic keratitis was investigated clinically. Corneas were studied for the inflammatory cell infiltration, and the CD3-, CD4- and CD8-positive cells were analysed by immunohistochemistry. The IL-2, -4, 10 and IFN-gamma content was measured in the corneas. Virus replication in the eyes was analysed by a plaque-assay. The DTH-response, the HSV-specific T cell proliferation and the serum neutralizing antibody-titres were investigated. DMF increased IL-4 and IL-10, but not IL-2 and IFN-gamma, secretion in activated lymphocytes from the spleen. Incidence and severity of stromal HSV-1 keratitis was reduced in the DMF group (P < 0.01). In the corneas from DMF-treated mice, the numbers of CD3+ and CD4+ cells were decreased and IL-4 was increased. Severity of epithelial disease and the virus-clearance from the eyes did not differ between the PBS and DMF group of mice. DTH, HSV-specific T cell proliferation and the neutralizing antibody-titres were not impaired. DMF increased the T helper-2-cytokine secretion in activated lymphocytes. After corneal HSV-1 infection, corneas from DMF treated mice had increased IL-4 content. This is associated with an improvement of herpetic stromal keratitis and reduced corneal T cell infiltration. DMF did not impair the systemic antiviral response.

Protection of Rhesus Monkeys against Infection with Minimally Pathogenic Simian-Human Immunodeficiency Virus: Correlations with Neutralizing Antibodies and Cytotoxic T Cells

We studied the capacity of active immunization of rhesus monkeys with HIV-1 envelope protein (Env) to induce primary virus cross-reactive neutralizing antibodies to prevent infection following intravenous challenge with simian-human immunodeficiency virus (SHIV). Monkeys were immunized with the human immunodeficiency type 1 (HIV-1) strain R2 Env. Initially, the Env was expressed in vivo by an alphavirus replicon particle system, and then it was administered as soluble oligomeric gp140. Concurrently, groups of monkeys received expression vectors that encoded either simian immunodeficiency virus (SIV) gag/pol genes or no SIV genes in vivo to test the additional protective benefit of concurrent induction of virus-specific cell-mediated immune (CMI) responses. Groups of control monkeys received either the gag/pol regimen or sham immunizations. The antibodies induced by the Env immunization regimen neutralized diverse primary HIV-1 strains. Similarly, potent CMI responses were induced by the gag/pol regimen, as measured by gamma interferon enzyme-linked immunospot assays. Differences in the responses among groups of monkeys strongly suggested that there was interference between the Env and gag/pol immunization regimens. Complete protection of some of the monkeys against infection after intravenous challenge with the partially pathogenic SHIV(DH12R (Clone 7)) was associated independently with both neutralizing antibody and CMI responses. Protection was associated with SHIV(DH12 (Clone 7)) serum neutralizing antibody titers of > or =1:80 or with cellular immune responses corresponding to >2,000 spot forming cells per 10(6) peripheral blood mononuclear cells. Immunization was also associated with a reduction in the magnitude and duration of virus load. Induction of cross-reactive, primary HIV-1-neutralizing antibodies is feasible and, when potent, may result in complete protection against infection with a heterologous challenge virus strain.