ABSTRACT
DNA vaccines are capable of priming the immune system of neonates in the presence of maternal antibodies. However, it is still not clear whether the extent of priming and protection against challenge infections induced by a DNA vaccine in maternally immune newborns is better than that induced by conventional vaccines. To study this, we used the pseudorabies virus (PRV) infection model in the natural host, the pig. We compared the efficacy of a DNA vaccine with the efficacy of a conventional modified live vaccine (MLV) and an inactivated vaccine (IV) in maternally immune newborn piglets. We measured the priming of the immune response and the degree of protection against challenge infection for all vaccine types. We vaccinated piglets with or without maternal immunity twice, at the age of 5 and 9 weeks, and we assessed protection by challenge infection with virulent PRV at the age of 15 weeks. Vaccination with DNA or conventional vaccines induced both humoral and cell-mediated immune responses in maternally immune animals. DNA vaccination seemed not to suffer from suppression by maternal immunity and resulted in similar or stronger immune responses in maternally immune piglets as compared in naïve piglets. In contrast, vaccination with conventional vaccines resulted in weaker immune responses in maternally immune piglets than in naïve piglets. Moreover, DNA vaccination provided better protection against challenge infection in maternally immune piglets than in naive piglets, whereas vaccination with conventional vaccines did not.
Subject(s)
Immunity, Maternally-Acquired/immunology , Pseudorabies Vaccines/immunology , Pseudorabies/prevention & control , Vaccines, DNA/immunology , Viral Envelope Proteins/immunology , Animals , Antibodies, Viral/blood , Disease Models, Animal , Enzyme-Linked Immunosorbent Assay , Female , Herpesvirus 1, Suid/isolation & purification , Immunity, Cellular , Immunoglobulin G/blood , Immunoglobulin M/blood , Interferon-gamma/biosynthesis , Lymphocytes/immunology , Neutralization Tests , Oropharynx/virology , Pseudorabies Vaccines/administration & dosage , Pseudorabies Vaccines/genetics , Swine , Vaccines, DNA/administration & dosage , Viral Envelope Proteins/geneticsABSTRACT
The aim of our study was to evaluate the relative importance of antibody and T cell-mediated immunity in protection against pseudorabies virus (suid herpes virus type 1) infection in pigs. We induced different levels of immune responses by using: (1) a modified live vaccine; (2) the same modified live vaccine with an oil-in-water (o/w) adjuvant; (3) an inactivated vaccine; and (4) the same inactivated vaccine with an o/w adjuvant. Subsequently, we challenged pigs with virulent pseudorabies virus (PRV). We demonstrated that best-protected pigs stood out by maintaining strong T cell-mediated immune (CMI) responses after challenge. Of the immune parameters tested, protection against virus shedding was correlated best with the magnitude of the IFN-gamma response of in vitro re-stimulated peripheral blood mononuclear cells (PBMC) with an additional role for PRV-specific IgG2 antibodies. The use of an o/w adjuvant resulted in higher antibody and CMI responses, in particular with an increased frequency of memory T helper blast cells of in vitro re-stimulated PBMC. However, this adjuvant-induced enhancement of the immune response had a limited additional effect on the efficacy of inactivated vaccines. This study suggests a major contribution of the CMI response in early protection against PRV infection and that PRV-induced IFN-gamma responses may serve as a suitable indicator for assessing the immune status of vaccinated pigs.
Subject(s)
Herpesvirus 1, Suid/immunology , Pseudorabies Vaccines/immunology , Pseudorabies/immunology , Swine Diseases/virology , Vaccination/veterinary , Adjuvants, Immunologic/pharmacology , Animals , Antibodies, Viral/blood , Cell Division/immunology , Enzyme-Linked Immunosorbent Assay/veterinary , Flow Cytometry/veterinary , Immunoglobulin Isotypes/immunology , Immunophenotyping/veterinary , Interferon-gamma/immunology , Lymphocytes/cytology , Lymphocytes/immunology , Neutralization Tests/veterinary , Pseudorabies/prevention & control , Pseudorabies/virology , Random Allocation , Specific Pathogen-Free Organisms , Swine , Swine Diseases/immunology , Swine Diseases/prevention & control , Vaccines, Attenuated/immunology , Vaccines, Attenuated/standards , Vaccines, Inactivated/immunology , Vaccines, Inactivated/standardsABSTRACT
Peptides deduced from the C-terminal end (residues 191 to 227) of pestivirus envelope protein E(rns) were used to develop enzyme-linked immunosorbent assays (ELISAs) to measure specifically antibodies against different types of pestiviruses. The choice of the peptide was based on the modular structure of the E(rns) protein, and the peptide was selected for its probable independent folding and good exposure, which would make it a good candidate for an antigenic peptide to be used in a diagnostic test. A solid-phase peptide ELISA which was cross-reactive for several types of pestivirus antibodies and which can be used for the general detection of pestivirus antibodies was developed. To identify type-specific pestivirus antibodies, a liquid-phase peptide ELISA, with a labeled, specific classical swine fever virus (CSFV) peptide and an unlabeled bovine viral diarrhea virus peptide to block cross-reactivity, was developed. Specificity and sensitivity of the liquid-phase peptide ELISA for CSFV were 98 and 100%, respectively. Because the peptide is a fragment of the E(rns) protein, it can be used to differentiate between infected and vaccinated animals when a vaccine based on the E2 protein, which is another pestivirus envelope protein, is used.
Subject(s)
Antibodies, Viral/blood , Enzyme-Linked Immunosorbent Assay/methods , Pestivirus Infections/veterinary , Swine Diseases/diagnosis , Viral Envelope Proteins/immunology , Amino Acid Sequence , Animals , Antigens, Viral/immunology , Molecular Sequence Data , Peptides/chemical synthesis , Peptides/chemistry , Peptides/immunology , Pestivirus/immunology , Pestivirus Infections/diagnosis , Pestivirus Infections/virology , Swine , Swine Diseases/virology , Viral Envelope Proteins/chemistryABSTRACT
OBJECTIVE: To determine antibody titer against bovine respiratory syncytial virus (BRSV) in dairy calves on farms and to investigate whether passively acquired antibody titers differ in calves born in various seasons. SAMPLE POPULATION: Serum samples from 129 colostrum-fed replacement calves in 8 dairy herds. PROCEDURE: A standard ELISA was used to determine BRSV-specific antibodies in serum samples obtained monthly, and antibody titers for calves born in various seasons were compared. RESULTS: BRSV-specific antibody titer in colostrum-fed dairy calves decreased to undetectable values at 3 to 4 months old. Calves born in winter generally had lower titers, compared with those for calves born in other seasons (P < 0.05). Titers in calves born in seasons other than winter did not differ. CONCLUSIONS AND CLINICAL RELEVANCE: Calves born in winter generally have lower BRSV-specific antibody titers, which may be caused by generally lower antibody titers in colostrum or by factors influencing colostrum intake.
Subject(s)
Antibodies, Viral/blood , Cattle Diseases/immunology , Immunity, Maternally-Acquired , Respiratory Syncytial Virus Infections/veterinary , Respiratory Syncytial Virus, Bovine/immunology , Animals , Animals, Newborn , Cattle , Colostrum/immunology , Enzyme-Linked Immunosorbent Assay/veterinary , Female , Regression Analysis , Respiratory Syncytial Virus Infections/immunology , SeasonsABSTRACT
Bovine respiratory syncytial virus (BRSV) strains are tentatively divided in subgroups A, AB and B, based on antigenic differences of the G protein. A Dutch BRSV strain (Waiboerhoeve: WBH), could not be assigned to one of the subgroups, because the strain did not react with any monoclonal antibody against the G protein. We describe here that the WBH strain has accumulated critical mutations in subgroup-specific domains of the G protein gene, which also occur but then independently in G protein genes of BRSV subgroup A or B strains. Although the comparison of nucleotide residues 256-792 of the G gene of the WBH strain with those of subgroup A and B strains showed that the G gene of the WBH strain is different from that of BRSV subgroup A and B strains, the sequence divergence was not more than observed within the G genes of human respiratory syncytial virus subgroup A or B strains. The WBH strain did not induce severe disease after experimental infection of calves, and induced partial protection against a heterologous challenge. Despite the dissimilarity of the conserved central regions of the G protein of the WBH strain and that of the challenge strain, a secondary antibody response against this region was induced in WBH-infected calves after challenge. We conclude that complete BRSV virus can partially protect against a BRSV infection with a strain that contains an antigenic dissimilar G protein.
Subject(s)
Cattle Diseases/prevention & control , Respiratory Syncytial Virus Infections/veterinary , Respiratory Syncytial Virus, Bovine/genetics , Respiratory Syncytial Virus, Bovine/immunology , Viral Envelope Proteins/genetics , Amino Acid Sequence , Animals , Antibodies, Viral/blood , Antibody Formation , Antigens, Viral/genetics , Antigens, Viral/immunology , Base Sequence , Cattle , Cattle Diseases/immunology , Chlorocebus aethiops , Evolution, Molecular , Humans , Molecular Sequence Data , Mutation , Netherlands , Phylogeny , Respiratory Syncytial Virus Infections/immunology , Respiratory Syncytial Virus Infections/prevention & control , Respiratory Syncytial Virus, Human/genetics , Respiratory Syncytial Virus, Human/immunology , Reverse Transcriptase Polymerase Chain Reaction , Sequence Alignment , Sequence Homology, Amino Acid , Sequence Homology, Nucleic Acid , Sheep , Sheep Diseases , Vero Cells , Viral Envelope Proteins/immunologyABSTRACT
We compared the protection afforded by three different DNA application methods against bovine respiratory syncytial virus (BRSV) infection in cattle. A synthetic gene that codes for the G protein of BRSV was inserted into a eukaryotic vector and was used in the vaccine. Intradermal (i.d.) application with a needleless injector (NI), the Pigjet, reduced BRSV excretion significantly better after BRSV challenge than intramuscular (i.m.) or i.d. vaccination with a needle. Serum antibodies against the G protein were consistently the highest and showed less variation in Calves vaccinated with the NI compared with those in i.m. and i.d. vaccinated calves. After BRSV challenge, secondary serum and mucosal antibody responses were also the highest in NI vaccinated calves. We conclude that DNA application with the needleless injector is substantially better than i.m. or i.d. application, and is capable to prime the immune response at the respiratory mucosa.
Subject(s)
Respiratory Syncytial Virus Infections/prevention & control , Respiratory Syncytial Virus, Bovine/immunology , Vaccines, DNA/administration & dosage , Viral Vaccines/administration & dosage , Virus Shedding , Animals , Antigens, Viral/immunology , Cattle , Nasal Lavage Fluid/virology , Respiratory Syncytial Virus Infections/virology , Vaccination , Viral Envelope Proteins/immunologyABSTRACT
A gE-negative bovine herpesvirus 1 (BHV1) vector vaccine carrying a gene coding for the G protein of bovine respiratory syncytial virus (BRSV) (BHV1/BRSV-G) induced the same high degree of protection in calves against BRSV infection and BHV1 infection as a multivalent commercial vaccine. A DNA plasmid vaccine, carrying the same gene as the BHV1/BRSV-G vaccine, significantly reduced BRSV shedding after BRSV infection compared with that in control calves, but less well than the BHV1/BRSV-G vaccine. Flow cytometric analysis showed a significant relative increase of gamma/delta+ T cells in peripheral blood after BRSV challenge-infection of the calves of the control group but not in the vaccinated groups. These results indicate that the G protein of BRSV can induce significant protection against BRSV infection in cattle, and that the BHV1/BRSV-G vaccine protects effectively against a subsequent BRSV and BHV1 infection.
Subject(s)
Cattle Diseases/prevention & control , Herpesviridae Infections/veterinary , Herpesvirus 1, Bovine/immunology , Respiratory Syncytial Virus Infections/veterinary , Respiratory Syncytial Virus, Bovine/genetics , Vaccination/veterinary , Vaccines, Combined/therapeutic use , Vaccines, DNA/therapeutic use , Viral Envelope Proteins/genetics , Viral Envelope Proteins/immunology , Viral Vaccines/therapeutic use , Animals , Antibodies, Viral/immunology , Cattle , Cattle Diseases/immunology , Herpesvirus 1, Bovine/genetics , Respiratory Syncytial Virus Infections/immunology , Respiratory Syncytial Virus, Bovine/immunology , T-Lymphocyte Subsets/immunology , Vaccines, Combined/genetics , Vaccines, Combined/immunology , Vaccines, DNA/genetics , Viral Vaccines/genetics , Viral Vaccines/immunologyABSTRACT
Peptides deduced from the central conserved region (residues 158 to 189) of protein G of human respiratory syncytial virus (HRSV) subtypes A and B were used as antigens in subtype-specific enzyme-linked immunosorbent assays (G-peptide ELISAs). These G-peptide ELISAs were compared with seven other serological assays to detect HRSV infection: ELISAs based on complete protein G, on fusion protein F, and on nucleoprotein N; a complement fixation assay; a virus neutralization test; and ELISAs for the detection of immunoglobulin A (IgA) or IgM antibodies specific for HRSV. In paired serum samples from patients with HRSV infection, more infections were diagnosed by the G-peptide ELISA (67%) than by all other serological tests combined (48%). Furthermore, for 16 of 18 patients (89%), the G-peptide ELISAs were able to differentiate between antibodies against HRSV subtypes A and B. This study shows that peptides corresponding to the central conserved region of the attachment protein G of HRSV can successfully be used as antigens in immunoassays. The G-peptide ELISA appeared to be more sensitive than conventional tests for the detection of HRSV antibody titer rises.
Subject(s)
Antibodies, Viral/analysis , Enzyme-Linked Immunosorbent Assay/methods , HN Protein , Respiratory Syncytial Virus Infections/immunology , Respiratory Syncytial Viruses/immunology , Viral Proteins/immunology , Amino Acid Sequence , Antibodies, Viral/immunology , Antigens, Viral/immunology , Humans , Infant , Infant, Newborn , Molecular Sequence Data , Respiratory Syncytial Virus Infections/virology , Sensitivity and Specificity , Viral Envelope ProteinsABSTRACT
The fusion protein F of bovine respiratory syncytial virus (BRSV) is an important target for humoral and cellular immune responses, and antibodies against the F protein have been associated with protection. However, the F protein can induce antibodies with different biological activity, possibly related to distinct antigenic regions on the protein. Therefore, epitopes were mapped on the F protein using monoclonal antibodies. Two epitopes (A and B) were identified that induced neutralizing antibodies, and one epitope (C) that did not elicit neutralizing antibodies. Subsequently, antibody responses were analysed against these epitopes in cattle sera after natural infection, experimental infection or vaccination. After natural infection or reinfection, the antibody titres against epitope A were significantly higher than those against epitope B or C. After experimental infection and after vaccination with an inactivated vaccine, antibody titres against epitope B and C were significantly higher than after natural infection. Conversely, virus neutralizing antibody titres were significantly lower in these animals with higher antibody titres against epitopes B and C than in naturally infected cattle. Because after natural infection the epitope-specific-antibody titres against epitope A, B or C differed markedly between the cattle, the magnitude of the antibody titres against epitope A, B or C in relation to the major histocompatibility complex (MHC) genes of cattle (BoLA) was studied. The magnitude of the antibody responses against epitope A of the F protein, but not against the G protein, appeared to be associated with the bovine lymphocyte antigen (BoLA) haplotype.
Subject(s)
Antibodies, Viral/immunology , Antigens, Viral/immunology , Cattle Diseases/immunology , Epitope Mapping , Epitopes, B-Lymphocyte/immunology , HN Protein , Respiratory Syncytial Virus Infections/veterinary , Respiratory Syncytial Virus, Bovine/immunology , Viral Proteins/immunology , Viral Vaccines/immunology , Animals , Cattle , Cattle Diseases/virology , Haplotypes , Respiratory Syncytial Virus Infections/immunology , Vaccination , Vaccines, Attenuated/immunology , Viral Envelope ProteinsABSTRACT
To identify putative persistent bovine respiratory syncytial virus (BRSV) infections in cattle, seven cattle that had experienced BRSV infections were treated with corticosteroids for two periods of 5 days. During the 5-day periods and the 3 weeks after treatment, attempts were made to isolate BRSV from lung lavage fluid and nasal swab specimens. Fluorescent antibody tests were used to detect BRSV antigen in lung lavage cells. A BRSV specific polymerase chain reaction (PCR) assay was developed, and was performed on lung lavage samples of all seven cattle as well as on various tissues of five of the cattle. In addition, nasal swabs of 74 over-one-year-old cattle, in a closed dairy herd were also assayed by PCR. The virus or its RNA was not detected in putative carriers, by any of the methods used, whereas all positive controls were positive. After corticosteroid treatment, three of the seven cattle showed a fourfold rise in antibody titre, suggesting induction of virus replication. BRSV-seronegative sentinel calves, that were housed together with each corticosteroid-treated animal, did not develop antibodies to BRSV indicating that BRSV was not shed by corticosteroid-treated cattle, or was shed at a very low level. In addition BRSV was not detected in seropositive cattle in a closed farm in summer. Although we consider the rises in antibody titres against BRSV an indication for persistence of BRSV in cattle, BRSV or its RNA was not detected in infected cattle.
Subject(s)
Respiratory Syncytial Virus, Bovine/immunology , Animals , Antigens, Viral/analysis , Cattle , Fluorescent Antibody Technique , Polymerase Chain Reaction , RNA, Viral/genetics , Respiratory Syncytial Virus, Bovine/genetics , Respiratory Syncytial Virus, Bovine/isolation & purification , Sensitivity and SpecificityABSTRACT
Bovine respiratory syncytial virus is an important respiratory pathogen in cattle. Recently, subgroups of BRSV have been identified, based on antigenic differences. However, little is known about subgroups of BRSV that circulate in the cattle population. Therefore, we determined the reactivity of monoclonal antibodies (mAbs), directed against the G, F, or P protein of BRSV, with lung tissue from 47 calves, that suffered from severe respiratory disease. Fourteen animals (30%) proved to be infected with BRSV, because they all reacted with mAbs against the P or F protein, as detected by fluorescent antibody tests. Monoclonal antibodies against the G protein were able to discriminate between the BRSV-positive specimens: 7 strains were identified as subgroup A strains, and 5 strains as subgroup AB, which is introduced as BRSV subgroup in this paper. Two strains could not be identified unambiguously. It is concluded that BRSV subgroup A and AB were associated with severe respiratory disease, and that strains belonging to either subgroup circulated concurrently in the cattle population in the Netherlands.
Subject(s)
Antigens, Viral/analysis , Cattle Diseases , Lung/virology , Respiratory Syncytial Virus Infections/veterinary , Respiratory Syncytial Virus, Bovine/classification , Viral Envelope Proteins/analysis , Animals , Antibodies, Monoclonal , Cattle , Fluorescent Antibody Technique , Mice , Respiratory Syncytial Virus Infections/virology , Respiratory Syncytial Virus, Bovine/isolation & purificationABSTRACT
To reproduce experimentally clinical bovine respiratory syncytial virus (BRSV) infections in cattle, we isolated BRSV from a calf in the field that suffered from acute respiratory disease. Cell culture passage of the virus was avoided to prevent any modification of the biological properties of the virus. The isolated BRSV was passaged in specific-pathogen-free (SPF) calves. Lung lavage fluids of these calves, which contained at least 10(3) TCID50/ml BRSV and which were found to be free of other known respiratory pathogens, were collected and pooled for experimental infection. To reproduce a clinical BRSV infection, two groups of six SPF calves were inoculated intranasally with 2 ml of 10(3.9) TCID50/ml BRSV of the obtained virus stock. Another five calves, which were persistently infected with bovine virus diarrhoea virus (BVDV), were given the same inoculum. One group of six calves served as mock-infected controls. Clinical signs were closely monitored from 1 week before until 16 days after inoculation. Reproducible clinical signs consisting of significantly (p < 0.05) increased respiratory rates and elevated body temperatures were recorded but not in all BRSV-inoculated calves. Although clinical signs were induced by experimental infection with non-cell-culture-passaged BRSV, the respiratory signs were not as serious as in the most severe cases in the field.
Subject(s)
Cattle Diseases/etiology , Respiratory Syncytial Virus Infections/veterinary , Respiratory Syncytial Virus, Bovine/physiology , Administration, Intranasal , Animals , Antibodies, Viral/analysis , Antigens, Viral/analysis , Body Temperature/physiology , Body Weight/physiology , Bovine Virus Diarrhea-Mucosal Disease/physiopathology , Bronchoalveolar Lavage Fluid/virology , Cattle , Cattle Diseases/physiopathology , Cattle Diseases/virology , Cell Culture Techniques , Disease Models, Animal , Fluorescence , Respiration/physiology , Respiratory Syncytial Virus Infections/etiology , Respiratory Syncytial Virus Infections/physiopathology , Respiratory Syncytial Virus, Bovine/immunology , Specific Pathogen-Free OrganismsABSTRACT
Antibodies against the two major surface glycoproteins of bovine respiratory syncytial virus (BRSV), G and F, play a role in protection against BRSV-associated disease, but only the antibody response against the F protein has been well described. Therefore, we used a novel peptide-based enzyme-linked immunosorbent assay (G peptide-ELISA) to compare immunoglobulin G (IgG) and IgG subclass antibody responses against the G protein with the antibody response against the F protein, as measured by a conventional BRSV ELISA (F-ELISA). Experimental infection of cattle induced significantly lower antibody titers than did natural infection. After natural primary infection, G peptide-specific antibodies declined more rapidly and to lower levels than the F protein-specific antibodies. As a consequence, the G peptide-ELISA detected more reinfections than did the F-ELISA. Ratios of G- and F-specific IgG1/IgG2 antibody titers did not differ markedly after infection or vaccination. Interestingly, after natural infection calves did not develop an IgG2 response to the complete G protein. In contrast, adult cattle had high IgG2 titers against this protein. Vaccination with a live vaccine induced low antibody titers, similar to the titers after experimental infection, whereas vaccination with an inactivated vaccine induced high titers. The results indicate that the kinetics of the G- and F-specific antibody responses differ. Furthermore, the IgG subclass response against the unglycosylated central region of the G protein is similar to the IgG subclass response to the F protein, but the IgG subclass response differs from the response to the complete G protein.
Subject(s)
Antibodies, Viral/biosynthesis , HN Protein , Respiratory Syncytial Virus Infections/immunology , Respiratory Syncytial Virus Infections/veterinary , Respiratory Syncytial Virus, Bovine/immunology , Viral Envelope Proteins/immunology , Viral Proteins/immunology , Animals , Cattle , Enzyme-Linked Immunosorbent Assay , Immunoglobulin G/immunology , Kinetics , Respiratory Syncytial Virus Infections/etiologyABSTRACT
Peptides deduced from the central hydrophobic region (residues 158-189) of the G protein of bovine and ovine respiratory syncytial virus (RSV) and of human RSV subtypes A and B were synthesized. These peptides were used to develop ELISAs to measure specifically antibodies against these types and subtypes of RSV. We have evaluated the bovine RSV-G peptide in both an indirect ELISA and in a blocking ELISA. Specificity and sensitivity, relative to a routine diagnostic ELISA that detects antibodies against the RSV F-protein in bovine sera, were 98% and 92% respectively for the indirect peptide-based ELISA, and 98% and 98% for the blocking peptide-based ELISA. In paired serum samples, rises in antibody titer were detected more frequently with the indirect peptide-based ELISA than with the routine F-ELISA. Furthermore, the peptide-based G-ELISAs were able to differentiate between antibodies against BRSV and HRSV, and between those against BRSV and ORSV. In addition, the indirect peptide-based ELISA was selective for HRSV subtype A and B antibodies. This study shows that peptides, corresponding to the central hydrophobic region of the attachment protein G of several RSVs, can be used successfully as antigens in highly specific and sensitive immunoassays.
Subject(s)
HN Protein , Peptides/immunology , Respiratory Syncytial Virus Infections/diagnosis , Respiratory Syncytial Viruses/chemistry , Respiratory Syncytial Viruses/classification , Viral Proteins/immunology , Amino Acid Sequence , Animals , Antigens, Viral/chemistry , Antigens, Viral/immunology , Cattle , Enzyme-Linked Immunosorbent Assay , Humans , Molecular Sequence Data , Peptides/chemical synthesis , Peptides/chemistry , Rabbits , Respiratory Syncytial Virus Infections/virology , Serotyping , Sheep , Species Specificity , Viral Envelope Proteins , Viral Proteins/chemistryABSTRACT
To study the role of non-bovine species in the epidemiology of bovine respiratory syncytial virus (RSV) infections, sera obtained from 9 non-bovine animal species and from humans were examined for bovine RSV specific antibodies. Sera were mainly from animals and humans which had been in contact with cattle. Forty sera of each species were tested in an RSV specific whole virus ELISA as well as in a peptide based ELISA, that was developed to measure antibodies specific for bovine RSV. Antibodies directed against RSV were detected in over 50% of sera obtained from sheep, goat, cattle and human beings, and anti-RSV activity was also found in some roe and dogs and one horse. Antibodies to bovine RSV were found in sera of all tested cattle, 11 (27.5%) goats and in some other individual animals: 3 horses, 2 roe, 1 cat and 1 dog. These results indicate that of the investigated species, besides cattle only goats might play a role in the epidemiology of bovine RSV.
Subject(s)
Antibodies, Viral/analysis , Respiratory Syncytial Virus, Bovine/immunology , Amino Acid Sequence , Animals , Cats , Cattle , Dogs , Enzyme-Linked Immunosorbent Assay , Humans , Molecular Sequence Data , Peptides/chemistry , Peptides/immunologyABSTRACT
The interaction between two different bovine respiratory syncytial virus (BRSV) strains and bovine alveolar macrophages (BAMs) was studied in vitro. Bovine respiratory syncytial virus replicated minimally in BAMs and most of the virus produced remained cell-associated. Approximately 1 out of 1,000 BAMs produced infectious virus, a number that further declined during the 7 days of culture. In contrast, BAMs exposed to bovine parainfluenza 3 virus (PI3V) produced high amounts of infectious virus. The number of BAMs that contained BRSV antigen depended on the antigen load of the inoculum and not on the infectivity of the virus. Antibody mediated enhancement of infection was not detected. It is concluded that bovine alveolar macrophages exhibit a high intrinsic resistance to BRSV, but not to PI3V.
Subject(s)
Macrophages, Alveolar/microbiology , Respiratory Syncytial Virus, Bovine/growth & development , Animals , Antigens, Viral/analysis , Cattle , Cell Survival , Cells, Cultured , Parainfluenza Virus 3, Human/growth & development , Respiratory Syncytial Virus, Bovine/immunology , Virus ReplicationABSTRACT
To study the epidemiology of respiratory syncytial virus (RSV) infections during the year, the incidences of primary infections and reinfections were monitored by titrating antibodies to bovine RSV (BRSV) in cattle above 2 months of age in 6 dairy herds in the Netherlands. From August 1990 until September 1991, 884 cattle were sampled at one-month intervals. A total of 155 cattle, most under two years of age, had a primary antibody response. Antibody rises were found in 259 cattle of all ages. The highest incidences of BRSV infections were found in one period either in autumn or winter. In other seasons, primary infections were rare, whereas reinfections were not uncommon. In 5 out of the 6 herds, two seronegative sentinel calves were introduced at the end of the winter and none developed specific antibodies before the next winter. The observations strongly suggest that, in spite of regular reinfections, BRSV circulates during spring or summer at a very low level or not at all. Persistent BRSV infection in a number of cows might be a means for the virus to survive during summer, but a steady rate of reinfection of seropositive cows throughout the year at a low level might also maintain a reservoir of infectious virus. This study adds to the knowledge of frequency and timings of primary infections and reinfections of BRSV and it might contribute to the study of these issues of human RSV.