HI Antibody Research Articles

Rapid Detection of Newcastle Disease Virus (NDV) Antigen Using Fluorescein Isothiocynate-Conjugated Immunoglobulins to Replace Identification by Detection and to Add Antigen

In the present study, attempts were made to prepare fluorescein-conjugated polyclonal antibodies to be used for accurate routine diagnosis of NDV. Ten male boskat rabbits, ten male guinea pigs and two male goats were subcutaneously hyperimmunized with NDV (Lasota strain). The mean HI antibody titers raised against NDV in rabbits, guinea pigs and goats were 8, 7 and 8.5log2, respectively. The globulin contents of the prepared antisera were precipitated by ammonium sulphate and then conjugated with FITC. In order to evaluate the accuracy of the prepared conjugates in diagnostic purposes, direct FAT was applied for identification of NDV in impression smears prepared from various tissues of experimentally infected chickens using tenfold serial dilutions of the prepared conjugated antisera. Rabbits, guinea pig and goat conjugates showed clear positive reactions up to the dilution of 1/100000, 1/10000 and 1/1000000, respectively. The overall findings indicated that accurate and precise diagnosis of ND can be achieved by direct FAT using fluorescein-conjugated anti-NDV polyclonal antibodies.

Newcastle disease virus vaccination enhanced severity of Escherichia coli infection in chicken

The present study emphasizes the effect of LaSota vaccination on the experimental E. coli infection in chickens. 160 chicks, 7 day old were divided into four groups of 45 birds each in groups A and group B and 35 birds each in groups C and D. The chicks of groups B and C were given LaSota vaccine by intranasal route @ 106 EID 50 per bird at the age of 7 days. At 15 days age, the chicks of groups A and B were injected with 107 CFU of E. coli O78/chick, intraperitoneally. The chicks of group D were kept as control. The clinical signs such as loss of body weight, anorexia and respiratory distress were more severe in group B. The percent mortality was more in group B (37.7%) as compared to group A (20%). The protective HI (> log24 with 4HA units) titre against New castle disease in both the vaccinated groups was noticed from 15th day post vaccination. The highest HI antibody titre (log2 6.80±0.37) was noticed in group B at 29 DPV. An overall increase in serum antibody titre against E. coli infection was observed in group B as compared to group A. The severity of gross and histopathological changes such as fibrinous pericarditis and perihepatitis was of higher magnitude in group B as compared to group A. It is concluded that administration of NDV LaSota vaccines enhanced the severity of colibacillosis in chickens as evidenced by clinical signs, mortality, immunological response and pathological changes.

Sero-conversion of Avian Influenza Virus Subtype H9N2 in Non-Vaccinated Commercial Poultry Flocks

Sero-conversion of pathogenic subtypes (H5, H7 and H9) of Avian Influenza Virus types was studied in commercial poultry farms in the Province of Punjab, Pakistan during the years 2015-16. Out of 6731 morbid tissues, only 11 samples (4 from broiler, 4 from broiler breeder and 3 from commercial layers farms) were found positive for Avian Influenza Virus (AIV) H9N2 type. Only one isolate was found positive for H9N2 subtype from 17994 tracheal swab samples. All the 37163 cloacal swab samples were found negative. The sero-analysis of 133438 blood sera samples showed sero-conversion in 66219 samples (49.64%) against H9 virus in the non-vaccinated poultry flocks, when tested with Heamagglutination Inhibition test (HI). Highest sero-conversion was recorded in broiler breeder (49.20%) followed by broilers (47.47%), layer (46.25%) and Native/Desi birds (45.59%). Highest HI titres were recorded in the flocks from Muzaffargarh, Rawalpindi, Toba Tek Singh, Sargodha, Gujrat, Faisalabad, Sheikhupura, Jhelum and Pakpattan while Bahawalpur, Gujranwala, Lahore, Jhang, Okara and Multan had relatively lower level of HI antibody titres. In conclusion only one type of AIV subtype H9N2 is prevailing in the province of the Punjab, Pakistan.

Avian influenza virus H9N2 infections in farmed minks.

BackgroundThe prevalence of avian H9N2 viruses throughout Asia, along with their demonstrated ability to infect mammals, puts them high on the list of influenza viruses with pandemic potential for humans. In this study, we investigated whether H9N2 viruses could infect farmed minks.MethodsFirst, we conducted a serological survey for avian influenza virus antibodies on a random sample of the field-trial population of farmed minks. Then we inoculated farmed minks with A/Chicken/Hebei/4/2008 H9N2 viruses and observed the potential pathogenicity of H9N2 virus and virus shedding in infected minks.ResultsH9 influenza antibodies could be detected in most farmed minks with a higher seropositivity, which indicated that farmed minks had the high prevalence of exposure to H9 viruses. After infection, the minks displayed the slight clinical signs including lethargy and initial weight loss. The infected lungs showed the mild diffuse pneumonia with thickened alveolar walls and inflammatory cellular infiltration. Influenza virus detection showed that viruses were detected in the allantoic fluids inoculated supernatant of lung tissues at 3 and 7 days post-infection (dpi), and found in the nasal swabs of H9N2-infected minks at 3–11 dpi, suggesting that H9N2 viruses replicated in the respiratory organ, were then shed outwards. HI antibody test showed that antibody levels began to rise at 7 dpi.ConclusionsOur data provided the serological and experimental evidences that strongly suggested farmed minks under the natural state were susceptible to H9N2 viral infection and might be the H9N2 virus carriers. It is imperative to strengthen the H9N2 viral monitoring in farmed minks and pay urgent attention to prevent and control new influenza viruses pandemic prevalence.

The adjuvanticity of ophiopogon polysaccharide liposome against an inactivated porcine parvovirus vaccine in mice

In this study, the adjuvant activity of ophiopogon polysaccharide liposome (OPL) was investigated. The effects of OPL on the splenic lymphocyte proliferation of mice were measured in vitro. The results showed that OPL could significantly promote lymphocyte proliferation singly or synergistically with PHA and LPS and that the effect was better than ophiopogon polysaccharide (OP) at most of concentrations. The adjuvant activities of OPL, OP and mineral oil were compared in BALB/c mice inoculated with inactivated PPV in vivo. The results showed that OPL could significantly enhance lymphocyte proliferation, increase the proportion of CD4+ and CD8+ T cells, improve the HI antibody titre and specific IgG response, and promote the production of cytokines, and the efficacy of OPL was significantly better than that of OP. In addition, OPL significantly improved the cellular immune response compared with oil adjuvant. These results suggested that OPL possess superior adjuvanticity and that a medium dose had the best efficacy. Therefore, OPL can be used as an effective immune adjuvant for an inactivated PPV vaccine.

AS03-adjuvanted H7N1 detergent-split virion vaccine is highly immunogenic in unprimed mice and induces cross-reactive antibodies to emerged H7N9 and additional H7 subtypes

Avian H7 is one of several influenza A virus subtypes that have the potential to cause pandemics. Herein we describe preclinical results following administration of an investigational H7N1 inactivated detergent-split virion vaccine adjuvanted with the AS03 Adjuvant System. The adjuvanted H7N1 vaccine was highly immunogenic compared to the non-adjuvanted H7N1 vaccine in unprimed mice with less than 100ng of hemagglutinin antigen per dose. In addition, compared to the non-adjuvanted vaccine, the AS03-adjuvanted H7N1 vaccine also induced robust HI and VN antibody responses that cross-reacted with other H7 subtypes, including recently emerged H7N9 virus. These H7 data from the preclinical mouse model add to the existing H5 data to suggest that AS03 adjuvant technology may be generally effective for formulating antigen-sparing detergent-split virion vaccines against intrinsically sub-immunogenic avian influenza A virus subtypes.

EPIDEMIOLOGICAL HIGHLIGHTS ON SOME VIRUSES ASSOCIATED WITH INCREASED MORTALITY IN CHICKENS BRED IN SHARKIA GOVERNORATE.

In the present study 1317 serum samples obtained from 6 broiler flocks, 2 broiler breeders and 28 commercial layer flocks were examined for HI antibodies of {NDV, IBV (Mass-41, 4/91, and D-274), AIV (H5N1, H5N2, H5N3, H9, H7) and Adenov (EDS­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­76)}. Studying the vaccination protocols in flocks under investigation and their seroconversion had led us to speculate and conclude viral affections in the different localities of Sharkia governorate. Speculating viral affections was a very hard task because the Egyptian market is jammed with a great variety of protective vaccines this was conflicting during result interpretation. Positive immune titers for AIV-H7 in sharkia governorate was detected at June /2014 in (El-salhia, 10th of Ramadan, El-ibrahemia and Abo-hammed) in commercial layer flocks only. The seropositive samples that exceeded the cutoff values were 63 out of 1317 (4.8%). AIV-H9 high seropositive immune titers was constantly found in examined samples although their protective vaccines were neglected. AIV-H5N3 seropositive results was recorded in a totally non vaccinated flocks against H5 which reflect virus circulation in the poultry premises. Seropositive titer for IBV-D274 and EDS76 was recorded in a totally non vaccinated flocks against such antigens., which refer to their role in the total simultaneous incidence of disease and consequent mortality. From another point of view it should be noted that. Vaccinating chicken flocks following a ready made manuscript of the producing companies without prior evaluation of the maternally derived antibodies (MDA) or evaluating the immune titers before taking the decision of vaccination or even considering the disease situation in the area is possible cause for vaccine failure. Sentinel birds inclusion in poultry patches should be taken seriously to give a mirror for the circulating viral agents in the poultry premises. It worth to mention that a parallel bacteriological work was running during investigation of the causes of increased mortality or dropped egg production. This work revealed the isolation of a resistant bacteria of the (Kebseilla spp).

Subtype-specific influenza A virus antibodies in Canada geese (Branta canadensis)

Historically, surveillance for influenza A viruses (IAVs) in wild birds has relied on viral detection assays. This was largely due to poor performance of serological assays in wild birds; however, recently developed commercial serological assays have improved the ability to detect IAV antibodies in wild birds. Serological surveillance for IAV antibodies in Canada geese (Branta canadensis) has shown that, despite a low prevalence of virus isolations, Canada geese are frequently exposed to IAVs and that exposure increases with latitude, which follows virus isolation prevalence patterns observed in dabbling ducks. The objectives of this study were to further evaluate IAV antibodies in Canada geese using a subtype-specific serological assay to determine if Canada geese are exposed to subtypes that commonly circulate in dabbling ducks. We collected serum samples from Canada geese in Minnesota, New Jersey, Pennsylvania, and Wisconsin and tested for antibodies to IAVs using a blocking ELISA. Positive samples were further tested by hemagglutination inhibition for 10 hemagglutinin IAV subtypes (H1–H10). Overall, we detected antibodies to NP in 24% (714/2919) of geese. Antibodies to H3, H4, H5, and H6 subtypes predominated, with H5 being detected most frequently. A decrease in H5 HI antibody prevalence and titers was observed from 2009 to 2012. We also detected similar exposure pattern in Canada geese from New Jersey, Minnesota, Washington and Wisconsin. Based on the published literature, H3, H4, and H6 viruses are the most commonly reported IAVs from dabbling ducks. These results indicate that Canada geese also are frequently exposed to viruses of the same HA subtypes; however, the high prevalence of antibodies to H5 viruses was not expected as H5 IAVs are generally not well represented in reported isolates from ducks.

Seroepidemiology of Avian Iinfluenza Viruses H5 and H9 in Beheira Governorate

Highly pathogenic avian influenza (HPAI) H5N1 virus remains a public health threat and continues to cause outbreaks among poultry as well as human. Since its appearance, the virus has spread to numerous geographic areas and is now considered endemic in Egypt. Also widespread prevalence of H9N2 subtype in the Middle East region and its detection in Egypt in summer 2011 in poultry added another challenge to the Egyptian poultry industry as well as human health. Here, to evaluate the potential for avian to human transmission of avian influenza viruses H5 and H9, a serological study was conducted among 60 poultry workers and housewives and 143 participants randomly selected from Respiratory Diseases Hospital (RDH) in Damanhour city in Behira governorate for determination of antibody titers against H5 and H9 avian influenza viruses by using hemagglutination inhibition assay. Further, participants were interviewed with a standardized questionnaire to assess the knowledge, attitudes, and practices regarding avian influenza infection. In addition, tissue samples from in contact poultry were assayed for virus detection using real time RT-PCR. Our results showed some evidence of exposure to H5N1 avian influenza virus with 3 (5%) poultry workers and 3 (2.1%) RDH subjects having HI antibody titer of 1:160. All sera of poultry workers and housewives tested negative for H9. Only three poultry samples were positive for H5N1 virus. The level of community knowledge about AI disease was fair, but their practice and attitude were negative. Therefore, designing and implementing health educational programs about AI to improve the community practices should have the priority. Our findings support the low transmissibility of H5N1 to humans, but transmission to highly exposed persons cannot be excluded given that HI antibody titers of 1:80 and 1:40 were detected in some individuals. Prevalence of H9 antibodies was low, however, requires additional studies.

Hemagglutinin glycosylation modulates the pathogenicity and antigenicity of the H5N1 avian influenza virus

The location and number of glycosylation in HA proteins exhibit large variations among H5 subtype avian influenza viruses (AIVs). To investigate the effect of glycosylation in the globular head of HA on the pathogenicity and antigenicity of H5N1 AIVs, seven rescued AIVs differing in their glycosylation patterns (144N, 158N and 169N) within the HA globular head of A/Mallard/Huadong/S/2005 were generated using site directed mutagenesis. Results showed that loss of glycosylation 158N was the prerequisite for H5 AIV binding to the α2,6-linked receptor. Only in conjunction with the removal of the 158N glycosylation, the H5 AIVs harboring both 144N and 169N glycosylations obtained an optimal binding preference to the α2,6-linked receptor. Compared with the wild-type virus, growth of viruses lacking glycosylation at either 158N or 169N was significantly reduced both in MDCK and A549 cells, while replication of viruses with additional glycosylation 144N was significantly promoted. Mutant viruses with loss of 158N or 169N glycosylation sites showed increased pathogenicity, systemic spread and pulmonary inflammation in mice compared to the wild-type H5N1 virus. In addition, chicken studies demonstrated that inactivated de-glycosylation 169N mutant induced cross-reaction HI and neutralization antibody against various clades of H5N1 AIVs. Moreover, this type of glycan pattern vaccine virus provided better cross-protection in chickens compared to wild-type vaccine virus. Thus, the glycosylation alteration of HA should be considered in the global surveillance and vaccine design of H5 subtype AIVs.

Uniform-sized water-in-oil vaccine formulations enhance immune response against Newcastle disease and avian influenza in chickens.

Water-in-oil (W/O) emulsion is one of the best "one-shot" delivery system for antigen to generate high and durable antibody response. Here a facile method using premixed Shirasu Porous Glass (SPG) membrane emulsification technique was employed to fabricate uniform-sized emulsion and mechanical stirring was employed to prepare non-uniform-sized emulsion as control. In release kinetics studies, uniform-sized emulsion showed low initial release, and during the followed 17 days, uniform-sized emulsions released antigen faster than emulsions of non-uniform size. In addition, vaccination studies against Newcastle disease virus (NDV) and avian Influenza virus (AIV) demonstrated that emulsion of uniform size induced higher HI antibodies and antigen-specific IgG titers. Furthermore, chickens vaccinated with emulsion of uniform size had a significantly greater ratio of CD8+ T cells to CD4+ T cells and a higher percentage of CD8+CD4+ T cells. Taken together, these results indicated that emulsion of uniform size induced a more potent immune response than emulsion prepared by mechanical stirring, and warranted the use of SPG membrane emulsification technique in generating new avian vaccines.

English

The study was conducted to assess the suitability of soaked parboiled cracked maize as a carrier of I-2 vaccine for oral immunization of village chickens. Chickens were vaccinated once via ocular route and orally with cracked maize at the second and fifth weeks of the experiment. Post vaccination serum was collected 4, 7, 9 and 11 weeks of the experiment and haemagglutination inhibition test was done to evaluate the antibody titer. The results show that chickens vaccinated via ocular route produce geometric mean log2 HI antibody titers of 5.71 and 5.51 at the fourth and seventh weeks of the experiment, respectively. On the other hand, the antibody titer of chickens vaccinated with coated cracked maize vaccine was 2.54 during the first vaccination; and during the booster vaccination, the titter increased to 2.92. Among the chickens vaccinated via ocular route, 90% (during the first vaccination) and 84.2% (during the booster vaccination) have titer above the protection titer of 3. Similarly, for chickens under cracked maize group, 54 and 74.8% of them were able to produce geometric mean log2 HI antibody titers ≥ 3. The current experimental study indicates that cracked maize can be good candidate carrier of I-2 vaccine virus with easy administration methods for village chickens. Keywords: Antibody, chickens, cracked maize, ocular, haemagglutination inhibition, I-2 vaccine. African Journal of Biotechnology , Vol 13(43) 4183-4187

A novel parainfluenza virus type 3 (PIV3) identified from goat herds with respiratory diseases in eastern China

Parainfluenza virus type 3 (PIV3) is one of the most important viral respiratory pathogens for humans and for many animals, but goat infection has been rarely reported. Starting in Aug 2013, goats in the Jiangsu and Anhui provinces of eastern China suffered severe respiratory diseases. In order to identify the causative agent, numerous related pathogens were tested with RT-PCR or PCR. A unique PIV3 strain was detected in most of the clinical nasal swabs or serum samples. The virus was isolated on MDBK cells and characterized by RT-PCR, nucleotide sequence analysis and hemagglutination test. The entire M and F gene coding regions, HN, 5′-UTR-N and L gene fragments were amplified using pairs of degenerate primers. Nucleotide, amino acid sequence alignments and phylogenetic analyses based on these genes indicated that the goat-derived PIV3 strain was distinct from previously reported BPIV3 genotypes and HPIV3 strains. The novel isolate, named JS2013, might be a potentially new member of the respirovirus genus. Goats were experimentally infected with JS2013 culture. The virus-inoculated goats displayed coughing and nasal discharges that were related to respiratory diseases. Viremia and virus shedding were detected during 4–10 days post-inoculation (dpi). Virus-specific HI antibodies became positive from 14dpi. This is the first report of the detection of PIV3 from Chinese goat herds and genetic and pathogenetic characterization of the novel goat-derived PIV3.

Active surveillance in poultry in Poland for avian influenza subtypes H5 and H7.

A serological surveillance programme for avian influenza A virus (AIV) subtype H5 and H7 in poultry was implemented in Poland in 2008-2013 with two main objectives: i) to detect subclinical infections or previous exposures to AIV H5 and H7 subtypes and ii) to demonstrate the AI- free status of Poland. During this period, over 45 000 serum samples from 2833 holdings were examined using the hemagglutination inhibition test (HI). The presence of HI antibodies was detected in 8 breeder geese holdings (7 positive for H5 and 1 positive for H7 AIV) and in 1 breeder duck holding (H5-positive), which represented 0.32% of all investigated holdings. All seropositive flocks were examined by real time RT-PCR with negative results, which substantiated the AI-free status of Poland. Positive results detected in clinically healthy poultry kept in an open range system indicate prior infections with low pathogenic AIV originating from the wild-bird reservoir.

Immunoprotection against influenza virus H9N2 by the oral administration of recombinant Lactobacillus plantarumNC8 expressing hemagglutinin in BALB/c mice

The H9N2 avian influenza virus (AIV) has become increasingly concerning due to its role in severe economic losses in the poultry industry. Transmission of AIV to mammals, including pigs and humans, has accelerated efforts to devise preventive strategies. To develop an effective oral vaccine against H9N2 AIV, a recombinant Lactobacillus plantarum NC8 strain expressing the hemagglutinin (HA) gene of H9N2 AIV was constructed in this study. Mice were orally immunized with the recombinant NC8-pSIP409-HA strain, and sIgA, IgG and HI antibodies were produced by the NC8-pSIP409-HA strain, which also induced CD8+ T cell immune responses. Most importantly, oral administration produced complete protection against challenge with mouse-adapted H9N2 virus. These results indicate that the recombinant NC8-pSIP409-HA was more effective at inducing the mucosal, humoral and cellular immune responses. Therefore, L. plantarum NC8-pSIP409-HA could become a promising oral vaccine candidate against H9N2 AIV.

Synergetic effects of subgroup J avian leukosis virus and reticuloendotheliosis virus co-infection on growth retardation and immunosuppression in SPF chickens

To further understand the effect of co-infection of subgroup J avian leukosis virus (ALV-J) and reticuloendotheliosis virus (REV) in specific-pathogen-free (SPF) white leghorn chickens, the experiment was made to study the pathogenicity, the weight of body and immune organs, response to newcastle disease virus (NDV) and avian influenza virus subtype H9 (AIV-H9) vaccination. Chickens were randomly divided into four groups, which includes injection groups (REV, ALV-J, REV plus ALV-J), and negative control group. The pathogenesis experiments indicated that chickens co-infected with REV and ALV-J had significantly higher mortality rate than those of the chickens infected with REV or ALV-J alone (P<0.05). Chickens inoculated with REV and ALV-J had significantly lower weights than chickens in all other groups (P<0.05). There were no significant differences between the two single infection groups and co-infection group (P>0.05) on bursa and thymus over body wt ratios, however, chickens co-infected with REV and ALV-J had significantly lower titers than REV-infected chickens and ALV-J-infected chickens on HI antibody titers to ND and AIV-H9 after vaccination (P<0.05). These findings suggested that the co-infection of REV and ALV-J caused more serious growth retardation and immunosuppression in SPF chickens.

Safety and immunogenicity in man of a cell culture derived trivalent live attenuated seasonal influenza vaccine: A Phase I dose escalating study in healthy volunteers

Live attenuated influenza vaccine (LAIV) offers the promise of inducing a variety of immune responses thereby conferring protection to circulating field strains. LAIVs are based on cold adapted and temperature sensitive phenotypes of master donor viruses (MDVs) containing the surface glycoprotein genes of seasonal influenza strains. Two types of MDV lineages have been described, the Ann Arbor lineages and the A/Leningrad/17 and B/USSR/60 lineages. Here the safety and immunogenicity of a Madin Darby Canine Kidney – cell culture based, intranasal LAIV derived from A/Leningrad/17 and B/USSR, was evaluated in healthy influenza non-naive volunteers 18–50 years of age. In a double-blind, randomized, placebo-controlled design, single escalating doses of 1×105, 1×106, or 1×107 tissue culture infectious dose 50% (TCID50) of vaccine containing each of the three influenza virus re-assortants recommended by the World Health Organization for the 2008–2009 season were administered intranasally. A statistically significant geometric mean increase in hemagglutination inhibition titer was reached for influenza strain A/H3N2 after immunization with all doses of LAIV. For the A/H1N1 and B strains, the GMI in HI titer did not increase for any of the doses. Virus neutralization antibody titers showed a similar response pattern. A dose–response effect could not be demonstrated for any of the strains, neither for the HI antibody nor for the VN antibody responses. No influenza like symptoms, no nasal congestions, no rhinorrhea, or other influenza related upper respiratory tract symptoms were observed. In addition, no difference in the incidence or nature of adverse events was found between vaccine and placebo treated subjects. Overall, the results indicated that the LAIV for nasal administration is immunogenic (i.e. able to provoke an immune response) and safe both from the perspective of the attenuated virus and the MDCK cell line from which it was derived, and it warrants further development.

Characterization of reverse genetics-derived cold-adapted master donor virus A/Leningrad/134/17/57 (H2N2) and reassortants with H5N1 surface genes in a mouse model.

Live attenuated influenza vaccines (LAIV) offer significant advantages over subunit or split inactivated vaccines to mitigate an eventual influenza pandemic, including simpler manufacturing processes and more cross-protective immune responses. Using an established reverse genetics (rg) system for wild-type (wt) A/Leningrad/134/1957 and cold-adapted (ca) A/Leningrad/134/17/1957 (Len17) master donor virus (MDV), we produced and characterized three rg H5N1 reassortant viruses carrying modified HA and intact NA genes from either A/Vietnam/1203/2004 (H5N1, VN1203, clade 1) or A/Egypt/321/2007 (H5N1, EG321, clade 2) virus. A mouse model of infection was used to determine the infectivity and tissue tropism of the parental wt viruses compared to the ca master donor viruses as well as the H5N1 reassortants. All ca viruses showed reduced replication in lungs and enhanced replication in nasal epithelium. In addition, the H5N1 HA and NA enhanced replication in lungs unless it was restricted by the internal genes of the ca MDV. Mice inoculated twice 4 weeks apart with the H5N1 reassortant LAIV candidate viruses developed serum hemagglutination inhibition HI and IgA antibody titers to the homologous and heterologous viruses consistent with protective immunity. These animals remained healthy after challenge inoculation with a lethal dose with homologous or heterologous wt H5N1 highly pathogenic avian influenza (HPAI) viruses. The profiles of viral replication in respiratory tissues and the immunogenicity and protective efficacy characteristics of the two ca H5N1 candidate LAIV viruses warrant further development into a vaccine for human use.

風疹HI 抗体価別によるワクチン接種ブースターの長期効果

This study was performed to clarify which titers of a pre-existing antibody could be efficiently boosted by vaccination and to assess the persistence of the antibodies. Two hundred healthy volunteer students with HI antibody titers of < or = 1:32 were enrolled. There were 6-16% of subjects with the negative HI antibody who had B-cell memory against rubella, because the EIA-IgM antibody remained negative and/or the avidity of the EIA-IgG antibody was high after vaccination. Furthermore most of them had already been vaccinated just once before. The ratio of those in whom the antibody levels increased significantly at one month after vaccination were 98%, 87%, 67% and 32% in subjects with an HI antibody titer of <1:8, < or =1: 8, < or =1:16 and < or =1:32 at pre-vaccination, respectively. The titers decreased significantly at two years after vaccination, however the ratio of decrease under each original level being 4%, 21.9%, 42.6% and 73.5% in each group of <1:8, < or =1: 8, < or =1:16 and < or = 1: 32, respectively. In comparison with the numbers of the subjects with <1: 8, the ones with < or = 1: 8, < or = 1:16 and < or = 1:32 increased 1.5-, 2.5- and 4.7-fold, respectively. Therefore, the recommendation of an HI antibody titer < or = 1:16 for vaccination in Japan is thought to be loose, although this is to decrease the risk of congenital rubella syndrome. We think that a new assay for cellular immunity for rubella should be developed in the future in order to ascertain whether congenital rubella syndrome will be prevented or not.

Pathogenicity and immunosuppresive properties of GM-97 strain of infectious bursal disease virus in commercial broiler chicken

The current study was conducted to evaluate the pathogenicity and immunosuppressive effects of GM-97 strain of infectious bursal disease virus in commercial broiler chickens. A total of 500 broiler chickens were vaccinated with the virus through oral route at 10 and 17 days of age (10 2 -10 3 EID50/dose). Chickens were also vaccinated with Newcastle disease virus (Hitchner B1) orally at 14 and 21 days old. Chickens were euthanized (at 12, 14, 16, 20, 23, 26 days of age) after measuring body weight. Bursa of Fabricius was examined for any gross lesion, weighed and processed for histological investigations. Bursa to body weight ratio and bursal lesion scoring were made to evaluate pathogenicity of the virus. Blood samples were analyzed for antibody response to ND vaccine virus using HI test. Results showed that the GM-97 strain of IBDV induced mild to moderate depletion of lymphoid cells in the center of bursal follicles and non-significant difference in bursa to body weight ratio amongst vaccinated and unvaccinated chickens. Chickens responded well to ND vaccine by mounting high level of serum NDV specific HI antibody titers. It can be concluded from the present study that GM-97 strain of IBDV has mild pathogenicity but is not immunosuppressive.