Specific Immune Serum Research Articles

Intermediate Levels of Pre-Existing Protective Antibody Allow Priming of Protective T Cell Immunity against Influenza.

Overcoming interfering impacts of pre-existing immunity to generate universally protective influenza A virus (IAV)-specific T cell immunity through vaccination is a high priority. In this study, we passively transfer varied amounts of H1N1-IAV-specific immune serum before H1N1-IAV infection to determine how different levels of pre-existing Ab influence the generation and protective potential of heterosubtypic T cell responses in a murine model. Surprisingly, IAV nucleoprotein-specific CD4 and CD8 T cell responses are readily detected in infected recipients of IAV-specific immune serum regardless of the amount transferred. When compared with responses in control groups and recipients of low and intermediate levels of convalescent serum, nucleoprotein-specific T cell responses in recipients of high levels of IAV-specific serum, which prevent overt weight loss and reduce peak viral titers in the lungs, are, however, markedly reduced. Although detectable at priming, this response recalls poorly and is unable to mediate protection against a lethal heterotypic (H3N2) virus challenge at later memory time points. A similar failure to generate protective heterosubtypic T cell immunity during IAV priming is seen in offspring of IAV-primed mothers that naturally receive high titers of IAV-specific Ab through maternal transfer. Our findings support that priming of protective heterosubtypic T cell responses can occur in the presence of intermediate levels of pre-existing Ab. These results have high relevance to vaccine approaches aiming to incorporate and evaluate cellular and humoral immunity towards IAV and other viral pathogens against which T cells can protect against variants escaping Ab-mediated protection.

Characterization of a Plasmodium falciparum PHISTc protein, PF3D7_0801000, in blood- stage malaria parasites.

During intraerythrocytic development Plasmodium falciparum deploys numerous proteins to support erythrocyte invasion, intracellular growth and development, as well as host immune evasion. Since these proteins are key for parasite intraerythrocytic survival and propagation, they represent attractive targets for antimalarial vaccines. In this study we sought to characterize a member of the PHISTc family of proteins, PF3D7_0801000, as a potential vaccine target. Using the wheat germ cell-free system we expressed the N-terminal region of PF3D7_0801000 (G93-L494, PF3D7_0801000N) and generated specific immune sera. We observed that PF3D7_0801000 localizes in merozoites, and antibodies against PF3D7_0801000N modestly inhibit P. falciparum parasite growth in in vitro culture. Sliding window analysis of the coding sequence revealed that pf3d7_0801000n is relatively conserved among African parasite isolates. Antibody profiles in a malaria-exposed Ugandan population revealed that PF3D7_0801000N is strongly immunoreactive with antibody acquisition increasing with age. Taken together, these findings suggest the need for further evaluation of PF3D7_0801000 for its role in merozoite invasion and utility as an asexual blood-stage vaccine candidate antigen.

FEATURES OF THE IMMUNOGENETIC STRUCTURE OF PIGS OF DOMESTIC BREEDS, SUITABLE FOR XENOTRANSPLANTATION

The aim of the work was to determine the immunogenetic characteristics of pigs of two Ukrainian breeds by their adaptability, resistance, reproduction, genetic homogeneity, the presence of alleles that determine the potential suitability for use in xenotransplantation and other biomedical purposes. At present, there is no breed or specialized line of pigs in Ukraine to address the urgent problems of humane medicine. However, there is a favorable situation for the creation of such a breed or the withdrawal of a specialized line because of the demand of pharmacological concerns for model biological objects to study the mechanisms of action of modern medical preparations, to develop methods of conducting bloodless surgical operations, modeling of the clinic and epidemiology of infectious diseases of different diseases. immune response, etc. In this context, there was a compelling reason to preserve the indigenous breeds of pigs of Ukraine, especially Ukrainian meat and Мyrgorod. Standard methods of immunogenetic analysis of pigs were used. The erythrocyte antigens of 9 blood group systems were determined using specific immune sera and the involvement of a bank of immunodiagnostics meeting international requirements. Blood groups were determined by the reaction of agglutination, an indirect Coombs test, and a hemolytic test. Statistical processing of the research results was performed using mathematical statistics using the GenAlex-6.0 computer program. As a result of the immunogenetic analysis of Ukrainian beef and myrrh-pig breeds, it was determined that each of them is characterized by a specific immunogenic profile, which is related to both breed characteristics and differences, and methods of their breeding. The difference between the distribution of the overwhelming number of alleles of blood groups was statistically significant. Pigs of Ukrainian meat and Мyrgorod breeds had the largest differences in allele distribution by B, E, F, K, L blood group systems with the presence of the Ladhjk marker allele in the latter (p < 0.05). The specificity of immunogenic profiles was evaluated, depending on the history of creation and the direction of the animal's performance. Species of Myrhorod and Ukrainian meat breeds with the presence of genotypes A - / - and Ebdgkmp / bdgkmp were found to determine the suitability of animals for xenotransplantation. Of the 80 animals tested for immunogenetic markers, only 24 individuals met the established selection criteria. The range of determined indicators of actual homozygosity for selected genotype animals ranged from 55.56% to the maximum value – 88.89%, mainly in sows from the Smorodinа, Rusalkа, Sorokа and Soyka families. According to molecular genetic analysis, you have been informed that the established criteria of the biomedical model meet only 13 individuals of Ukrainian meat breed. Among animals with the highest index of actual homozygosity, representatives of Cererа and Cіlina were identified, with Celina 4092 being homozygous for all blood group systems studied. The selection of pigs for blood alleles, desirable for xenotransplantation, with their transfer to the homozygous state: A -/- and Ebdgkmp / bdgkmp will impair the adaptive, first of all, reproductive qualities of the animals and create significant problems for the cultivation of such individuals. The possibility of the occurrence of reproductive and resistance disorders of pigs in the selection of blood groups genotypes modeled for xenotransplantation and the search for ways to overcome them are being considered.

Isolation and immunoblotting of somatic antigens of Cotylophoron cotylophorum and Gastrothylax crumenifer

Paramphistomosis is the emerging fluke infection in young ruminants which results in high morbidity and mortality in tropics and sub-tropics. The present study was carried out to detect the sharing antigens among the purified somatic antigens of G. crumenifer and C. cotylophorum, in order to use as a candidate antigen for diagnosis of paramphistomosis in sheep. Immunoblot analysis of the purified somatic antigens of C. cotylophorum and G. crumenifer using their specific rabbit hyper immune serum revealed 3 common polypeptides at the range of 27, 29 and 60 kDa. Hence these three immunodominant peptides can be used candidate antigens in development of vaccines against ovine paraphistomosis and also for early diagnosis of infection.

Using Real-Time RT-PCR Reagent Kits for Identity Testing of Measles, Mumps and Rubella Vaccines

Currently, the identity of measles, mumps and rubella virus vaccines is determined during certification testing by a labour-consuming, lengthy and costly neutralisation test using cell cultures. The identity of the virus contained in such vaccines is established based on neutralisation of cytopathic effect of viruses in sensitive RK-13 and Vero cell cultures using a specific immune serum. An urgent challenge is to simplify and reduce the cost of controlling the identity of commercial batches of measles, mumps and rubella vaccines using polymerase chain reaction (PCR) tests. The aim of the study was to determine the possibility of viral ribonucleic acid (RNA) detection in these vaccines using reagent kits from different manufacturers for detection of measles, mumps and rubella viruses in clinical material by real-time reverse transcription-PCR (RT-PCR). The article presents the results of the study, which assessed the possibility of using the real-time RT-PCR for testing the identity of measles, mumps and rubella viruses in vaccines. The authors of the study analysed domestically produced and foreign reagent kits intended for detection of measles, mumps and rubella viruses in clinical material. All the studied reagent kits were able to detect RNAs of the above-mentioned viruses in vaccine products. All the reagent kits demonstrated high specificity and could be used to confirm the identity of the measles, mumps and rubella viruses in all the studied vaccines. Commercial domestic reagent kits can be used to determine the identity of rubella vaccines by RT-PCR. However, it is advisable to develop domestic reagent kits for checking the identity of measles and mumps vaccines by RT-PCR. The acceptability of the test results was assessed using the industry reference standards of measles, mumps and rubella viruses activity with certified stable activity values.

Recombinant Zika NS1 Protein Secreted from Vero Cells Is Efficient for Inducing Production of Immune Serum Directed against NS1 Dimer.

Zika virus (ZIKV) is a mosquito-borne flavivirus that recently emerged in the South Pacific, Americas, and Caribbean islands, where the larger epidemics were documented. ZIKV infection in humans is responsible for neurological disorders and microcephaly. Flavivirus NS1 is a non-structural glycoprotein that is expressed on the cell surface and secreted as a hexameric lipoprotein particle. Intracellular NS1 exists as a dimer that is required for viral replication, whereas the secreted NS1 hexamer interacts with host factors, leading to pathophysiological conditions. In an effort to dispose of specific anti-ZIKV NS1 immune serum, Vero cells were transduced with a lentiviral vector containing the NS1 gene from an epidemic strain of ZIKV. We showed that stably transduced Vero/ZIKV NS1 cell clone was efficient in the secretion of recombinant NS1 oligomer. Immunization of adult rat with purified extracellular NS1 developed anti-ZIKV antibodies that specifically react with the NS1 dimer produced in human cells infected with African and Asian strains of ZIKV. The rat antibody against ZIKV NS1 dimer is a reliable biological tool that enables the immunological detection of secreted NS1 from host-cells infected with ZIKV.

Isolation of Pigeonpox Virus from Severe Infection of Pigeons in Diyala province: Virological and Histopathological Study

Pigeonpox virus was isolated from severe cases of avipoxvirus infection affecting 64 pigeons in Ba'aquba of Diyala governarate. The virus grew well on chorioallantoic membrane of chick embryos of 11-12 days old, and produced typical pock lesions. Histopathological sections of infected tissue samples revealed typical pox lesions. The virus was identified as Pigeonpox virus using of specific hyper immune serum and indirect immuno-flourescent and indirect immuno-peroxidase tests. The virus agglutinated RBCs of pigeon, fowl, turkey and duck. Experimental infection in pigeons produced moderate infection as compared to the diseased birds, while in chicken the virus produced mild infection.

Détection d’entérovirus dans les eaux usées urbaines à Yopougon, Abidjan

AimThe aim of this study was to determine prevalence of enteroviruses in raw municipal wastewater and specify serotypes circulating. MethodsAfter virus concentration by WHO recommend method, aqueous phase of 68 samples was inoculate on BGM, RD, L20B and Hep2 cells lines. Typing after titration was performed by microplate neutralization test with specific horse immune serum against EV (kit RIVM/WHO). NPEV strains were confirmed by RT-PCR test in 5′NC genomic region. Antigenic and molecular tests of Polioviruses intratypic differentiation were performed to determine vaccine or wild origin of Poliovirus strains. ResultsViral isolation obtained 43/68 (65.15 %) positives samples. Among these 35/43 (81. 39%) were EV and 8/43 (19.04 %) non EV strain. Among EVs, 34/35 (97.14 %) were NEPV and 2/35 (5.71 %) vaccinal Poliovirus strains type 2 (Sabin-like). NEPV typing gave 77 % untypeable strains by conventionally method. The average virus concentration estimated in the raw sewage is 4.28×105 PFU/L. ConclusionVarious contacts between people and these waters expose them to health risks.

The application of polymerase chain reaction in detection of bovine herpesvirus 1 in clinical samples

The objective of this study was the application of polymerase chain reaction in detection of bovine herpesvirus 1 in clinical samples. Twenty samples of bovine nasal swabs were separately inoculated in Vero cells. Laboratory strain TN 41 of bovine herpesvirus 1 served as a control in the experiment. The cytopathic effects were recovered in the cell line previously inoculated with a sample of bovine nasal swab, as well as in cells inoculated with the laboratory strain TN 41 of the bovine herpesvirus 1 after a period of incubation of 24h, 36h and 48h. Identification of the isolated strains of the virus was done by the virus - neutralization test with specific immune sera against BHV 1, with a titre of 1:16. Comparative analysis of DNA fragments of the laboratory strain of BHV1 and isolated strain obtained by polymerase chain reaction with primers for viral gB glycoprotein and thymidine-kinase coding region, confirmed that the isolated strain of the virus belongs to bovine herpesvirus 1 (BHV 1).

Purification of the recombinant beta2 toxin (CPB2) from an enterotoxaemic bovine Clostridium perfringens strain and production of a specific immune serum

Overgrowth of Clostridium perfringens clones with production of one or more of its toxin(s) results in diverse digestive and systemic pathologies in human and animals, such as cattle enterotoxaemia. The so-called beta2 toxin (CPB2) is the most recently described major toxin produced by C. perfringens. In this study, the cpb2 ORF ( cpb2FM) from a cattle C. perfringens-associated enterotoxaemia was cloned and sequenced. The cpb2FM and its deduced nucleotide sequence clearly corresponded to the cpb2 allele considered as “consensus” and not to “atypical” allele, despite its “non-porcine” origin. Expression assays of the recombinant toxin CPB2FM were performed in Escherichia coli and Bacillus subtilis with the expression vector pBLTS72, and by genomic integration by double recombination in B. subtilis. Highest level of production was obtained with the expression vector in B. subtilis 168 strain. The recombinant CPB2FM protein was purified and a specific rabbit polyclonal antiserum was produced. Polyclonal antibodies could detect CPB2 production in supernatants of C. perfringens from enterotoxaemic cattle.

Examination of the activity of HN and F glycoprotein antigens of the outer envelope of Newcastle disease virus by using fusional, hemolytic, hemagglutination and hemadsorption tests, in vitro

The objective of our study was to examine fusional, hemolytic, hemagglutination and hemadsorption activities of the surface glycoprotein HN and F antigens of Newcastle disease (ND) virus, in vitro. The samples of activated ND virions, induced Vero cell fusion after 6h, 12h, 24h and 48h. After 24h of treatment of the inoculated Vero cells with dilutions of the specific immune sera against ND virus, cell fusion was not registered at dilutions of 1:2 and 1:4. The ND virion samples, activated with 0.025 g/dL trypsin-versen, induced hemolysis of chicken erythrocytes at antigen dilutions of 1:4 and 1:8. The samples of activated ND virions, expressed an intensive hemagglutinating activity of 256 HAU/0,1 mL. After treatment of the abovementioned samples with specific immune sera against ND virus, hemolytic activities were not detected at immune sera dilution of 1:32. The hemadsorption of chicken erythrocytes at the surface of inoculated Vero cells was detected after 6h of inoculation with activated ND viruses. After 24h of treatment of inoculated Vero cells with dilutions of specific immune sera against ND virus, the hemadsorption of chicken erythrocytes was not registered at immune sera dilution of 1:64. These results showed the possibility to use fusion, hemolytic and hemadsorption tests for the detection of immunologically important glycoprotein antigens of ND viruses and their identification with specific immune sera. .

Study on Detection, Isolation and Identifications of Infectious Viruses in Various Water Samples

Various factors using cell lines can effect kinds and frequencies of infectious viruses obtained in the detection tests on various water samples. We tried to find out technical problems for the maximum virus isolations from water samples and characterize the virus isolates from waters in nature and in various purification stages. Fourteen viruses were isolated from 169 water samples by virus monitoring protocol for the information collection requirements rule, US EPA. The morphological changes caused by viruses and mycoplasma infections were compared with for increasing the specificity of tests employed. Cytopathic effects of slow growing viruses were found very similar with those by toxic effects in water samples and mycoplasma infections. Five of 6 stream water samples tested (83.33%) showed virus contaminations with the range of 1.03 to 5.75 MPNs/100 liter. Eight of 24 source water samples (33.35%) showed viral contaminations. One water sample of 24 water samples during precipitation stages was shown to include infectious viruses. It was confirmed that infectious viruses were significantly decreased by purification stages from streams. The titers (TCID??) of virus isolates were ranged as 10 -6.8 ~ 10 -6.925 /㎖. The virus isolates were identified by immune fluorescent antibody (IFA) method using virus specific immune sera and serotyped using serotype specific reference sera. Of 14 virus isolates, 7 samples were identified as poliovirus and the other 7 were identified as coxsakie virus. Of 7 polioviruses, one was serotyped as type I, 3 viruses as type II and another 3 as type Ⅲ. Conclusively, BGM cell lines must be free of mycoplasma for the strict examination of infectious viruses in water and highly sensitive for mainly enteroviruses. In addition, most of infectious viruses showing typical cytopathic effect from water samples were confirmed as coxsackie B and live attenuated vaccine strains of 3 polio types when BGM cells were used for virus isolations.

Examination of the activity of glycoprotein HN and F antigens of the outer envelope of the parainfluenza virus type 3 by using fusional, hemolytic and hemagglutination tests, in vitro

The objective of our study was to examine fusional, hemolytic and hem agglutinating activities of the surface glycoprotein HN and F antigens of parainfluenza virus type 3, in vitro. The samples of activated PI3 virions induced Vero cell fusion after 24 h and 48 h. After treatment of inoculated Vero cells was the dilutions of specific immune sera against PI3 virus, cell fusion were not registered at dilutions of 1:2, 1:4 and 1:8 of the immune sera. The samples of PI3 virions, activated by 0.025 g/dL trypsin-versen induced hemolysis at antigen dilution of 1:8. The samples of activated PI3 virions, expressed an intensive hemagglutinating activity of 128 HAU/0.1 mL. After treatment of the abovementioned samples with specific immune sera against PI3 virus, hemolytic activities were not detected at the dilution of 1:16 of specific immune sera. These results showed that the fusional and hemolytic tests can be used for fast detection of immunologically important glycoprotein antigens of PI3 virus and their identification with specific immune sera.

Investigations of hemadsorption characteristics of glycoprotein HN and F antigen of parainfluenza 3 virus outer membrane in vitro

The objective of our investigations was to examine the hemadsorption characteristics of glycoprotein HN and F antigens of the outer membrane of the parainfluenza 3 virus. Six hours following inoculation of the cell line with the Vero virus PI3, previously activated with 0.025 g/dl trypsinversen, the appearance of less intense hemadsorption was established in antigen dilutions of 1:2 and 1:4. Hemadsorption was established in the mentioned cell lines also 12 h after inoculation in virus dilutions of 1:8 and 1:16, while 24 h following inoculation, hemadsorption was present also in a virus dilution of 1:64. Inhibition of hemadsorption in inoculated cells with immune serum dilutions of 1:16 was established 24 h after inoculation of the cell line with Vero samples of the virus PI3, activated with trypsinversen and with the addition of specific immune serum. .

Investigations of hemadsorption characteristics of glycoprotein HN and F antigens of Newcastle Disease virus envelope in vitro

The objective of these investigations was to examine the hemadsorption characteristics of glycoprotein HN and F antigens of the Newcastle Disease virus envelope. Six hours following inoculation of the cell line with the Newcastle Disease Vero virus, previously activated with 0.025 g/dl trypsin-versene, the appearance of hemadsorption was established in a smaller intensity in antigens diluted in ratios from 1:8 to 1:16. Hemadsorption was also determined in the mentioned cell lines 12 hours following inoculation in viruses diluted 1:64, while hemadsorption was present in virus dilutions of 1:256 after 24 hours. Inhibition of hemadsorption in inoculated cells with immune serum dilutions of 1:64 was established 24 hours following inoculation of the cell line with Vero samples of the Newcastle Disease virus, activated with trypsin-versene and the addition of specific immune serum.

Subunits of the epithelial sodium channel family are differentially expressed in the retina of mice with ocular hypertension

Glaucoma is a prevalent cause of blindness, resulting in the apoptotic death of retinal ganglion cells and optic nerve degeneration. The disease is often associated with elevated intraocular pressure, however, molecular mechanisms involved in ganglion cell death are poorly understood. To identify proteins contributing to this pathological process, we analysed the retinal gene expression of DBA/2J mice that develop an elevated intraocular pressure by the age of 6 months with subsequent ganglion cell loss. In this study, we identified subunits of the epithelial sodium channel (ENaC) family that are specifically expressed under elevated intraocular pressure. Using reverse transcriptase polymerase chain reaction we observed a significant increase of alpha-ENaC in the neuronal retina of DBA/2J mice when compared with control animals, while beta-ENaC and gamma-ENaC were not detectable in this tissue. Specific immune sera to ENaC subunits showed up-regulation of alpha-ENaC in synaptic and nuclear layers of the retina, and in the retinal pigment epithelium. Consistent with our polymerase chain reaction data, beta-ENaC was not detected by specific antibodies in the retina, while gamma-ENaC was only present in the retinal pigment epithelium under ocular hypertension. Finally, the increase of alpha-ENaC gene expression in the neuronal retina and the retinal pigment epithelium was not observed in other tissues of DBA/2J mice. Since the intraocular pressure is regulated by the transport of aqueous humour across epithelial structures of the eye that in turn is associated with ion flux, the specific up-regulation of ENaC proteins could serve as a protecting mechanism against elevated intraocular pressure.

Expression of chimeric HCV peptide in transgenic tobacco plants infected with recombinant alfalfa mosaic virus for development of a plant-derived vaccine against HCV

Hepatitis C virus (HCV) is the major etiologic agent of blood transfusion–associated and sporadic non-A non-B hepatitis affecting more than 180 million worldwide. Vaccine development for HCV has been difficult and there is no vaccine or effective therapy against this virus. In this paper, we describe the development of an experimental plant-derived subunit vaccine against HCV. Our subunit vaccine originates from a consensus HCV-HVR1 epitope (R9) that antigenically mimics many natural HVR1 variants. This HVR1 sequence was cloned into the open reading frame of a plant virus, Alfalfa Mosaic Virus (ALMV) coat protein (CP). The chimeric ALMV RNA4 containing sequence-encoding R9 epitope was introduced into full-length infectious ALMV-RNA3 that was utilized as an expression vector. The recombinant chimeric protein is expressed in transgenic tobacco plants (P12) expressing ALMV RNA1 and 2. Plant–derived HVR1/ALMV-CP reacted with HVR1 and/or ALMV-CP specific monoclonal antibodies and immune sera from individuals infected with HCV. Using plant-virus based transient expression to produce this unique chimeric antigen will facilitate the development and production of an experimental HCV vaccine. A plant derived recombinant HCV vaccine can potentially reduce expenses normally associated with production and delivery of conventional vaccine. Key Words: Hepatitis C virus (HCV), transgenic tobacco plants (P12), consensus HCV HVR1 epitope (R9), and chimeric ALMV-RNA4. African Journal of Biotechnology Vol.3(11) 2004: 588-594

The identification of a Clonorchis sinensis gene encoding an antigenic egg protein

The cDNA library of Clonorchis sinensis was screened for genes encoding antigenic proteins by using sera from clonorchiasis patients. A gene of 888 bp encoding a 28-kDa protein (Cs28) was cloned and found to contain a high percentage of glycine (20%), tyrosine (11%), and lysine (11%). The amino acid sequence of Cs28 showed 60% homology with the vitelline B precursor protein of Opisthorchis viverrini and of 33% homology with the vitelline B1 and B2 proteins of Fasciola hepatica. A strong positive reaction was observed in the intrauterine eggs of adult C. sinensis by immunohistochemical analysis using specific immune sera against recombinant Cs28 protein (rCs28). By immunoblot analysis, rCs28 displayed an antigenic reaction with 73% of the serum samples from 115 cases of clonorchiasis. In addition, it cross-reacted with the sera of 77.5% of 40 opisthorchiasis cases, 90% of 20 schistosomiasis cases, and 50% of 10 paragonimiasis cases. However, no cross-reactions were observed with the sera of sparganosis or cysticercosis patients. In conclusion, the Cs28 protein was identified as an egg protein of C. sinensis and as an antigen common to the trematode species examined.

Antibody-dependent macrophage-mediated activity against Helicobacter pylori in the absence of complement.

Helicobacter pylori is a Gram-negative bacterium, which chronically infects the stomach. Little is known about the immune mechanisms limiting the spread of infection and/or contributing to protection after experimental immunization. In this study, we investigated the hypothesis that specific antibodies and host cells cooperate in the immunity against H. pylori. Antibody-dependent cellular activity against H. pylori was assessed using specific immune serum, or purified IgG, in an in vitro assay, with peritoneal cells as effector cells. The natural antibacterial activity of peritoneal cells was significantly augmented by H. pylori-specific antibodies in a dose-dependent manner. A novel finding was that this killing effect did not require functional complement. Most of the bactericidal activity was associated with cells that were adherent, DX5(-), CD19(-), CD11c(-), Thy-1.2(-), CD11b(+) and CD16/32(+), indicating that the main effector population was represented by macrophages. Similar antibacterial killing was obtained with the macrophage cell line GG2EE. Cytochalasin D significantly impaired this antibacterial activity, suggesting that phagocytosis plays a major role in the antibody-mediated H. pylori killing.

Role of immune sera in the in-vitro phagocytosis of Bordetella pertussis strains

In this study, phagocytosis of Bordetella pertussis was assessed using a human monocyte-derived macrophage line (THP-1) and immune sera from children who had received primary vaccination during the Italian clinical trial on the efficacy of two acellular three-component (PT-FHA-PRN) and one whole-cell pertussis vaccines. The results demonstrate that phagocytosis of opsonized bacteria with specific immune sera is not significantly enhanced compared with that of non-opsonized bacteria or bacteria opsonized with non-immune sera. A similar result was obtained also using B. pertussis strains showing variants of the pertactin antigen suggesting that those variations do not reduce the capability of the bacterium to invade the monocytes.