Passive Hemagglutination Assay Research Articles

1648. Prevalence of Orientia tsutsugamushi, Anaplasma phagocytophilum, and Leptospira interrogans in Striped Field Mice in Gwangju, Republic of Korea

BackgroundScrub typhus, anaplasmosis, and leptospirosis are well-known diseases that are considered common, widespread rodent-borne infectious diseasesMethodsThis study investigated the prevalence of Orientia tsutsugamushi, Anaplasma phagocytophilum, and Leptospira interrogans in wild rodents through molecular detection using organ samples and through serological assay using blood samples of mice collected from two distinct sites in Gwangju Metropolitan City, Republic of Korea (ROK).ResultsA total of 47 wild rodents, identified as Apodemus agrarius (A. agrarius), were captured from June to August 2016. The seroprevalence of antibodies against bacterial pathogens in A. agrarius sera was analyzed; 17.4% (8/46) were identified as O. tsutsugamushi through indirect immunofluorescence assay and 2.2% (1/46) were identified as Leptospira species through passive hemagglutination assay. Using polymerase chain reaction, the spleen, kidney and blood samples were investigated for the presence of O. tsutsugamushi, A. phagocytophilum, and L. interrogans. Out of the 47 A. agrarius, 19.1% (9/47) were positive for A. phagocytophilum and 6.4% (3/47) were positive for L. interrogans, while none were positive for O. tsutsugamushi. Four out of 46 (8.7%) blood samples, six out of 45 (13.3%) spleen samples, and one out of 47 (2.1%) kidney samples were positive for A. phagocytophilum. Three out of 47 (6.4%) kidney samples were positive for L. interrogans. The sequencing results of PCR positive samples demonstrated >99% similarity with A. phagocytophilum and L. interrogans sequencesConclusion A. phagocytophilum was mostly detected in the spleen, whereas L. interrogans was mostly detected in the kidneys. Notably, A. phagocytophilum and L. interrogans were detected in A. agrarius living in close proximity to humans in the metropolitan suburbans. The results of this study indicate that rodent-borne bacteria may be present in wild rodents in the metropolitan suburban areas of ROK Disclosures All authors: No reported disclosures.

Prevalence of Orientia tsutsugamushi, Anaplasma phagocytophilum and Leptospira interrogans in striped field mice in Gwangju, Republic of Korea.

This study investigated the prevalence of Orientia tsutsugamushi, Anaplasma phagocytophilum, and Leptospira interrogans in wild rodents through molecular detection using organ samples and through serological assay using blood samples of mice collected from two distinct sites in Gwangju Metropolitan City, Republic of Korea (ROK). A total of 47 wild rodents, identified as Apodemus agrarius (A. agrarius), were captured from June to August 2016. The seroprevalence of antibodies against bacterial pathogens in A. agrarius sera was analyzed; 17.4% (8/46) were identified as O. tsutsugamushi through indirect immunofluorescence assay and 2.2% (1/46) were identified as Leptospira species through passive hemagglutination assay. Using polymerase chain reaction, the spleen, kidney and blood samples were investigated for the presence of O. tsutsugamushi, A. phagocytophilum, and L. interrogans. Out of the 47 A. agrarius, 19.1% (9/47) were positive for A. phagocytophilum and 6.4% (3/47) were positive for L. interrogans, while none were positive for O. tsutsugamushi. Four out of 46 (8.7%) blood samples, six out of 45 (13.3%) spleen samples, and one out of 47 (2.1%) kidney samples were positive for A. phagocytophilum. Three out of 47 (6.4%) kidney samples were positive for L. interrogans. The sequencing results of PCR positive samples demonstrated > 99% similarity with A. phagocytophilum and L. interrogans sequences. A. phagocytophilum was mostly detected in the spleen, whereas L. interrogans was mostly detected in the kidneys. Notably, A. phagocytophilum and L. interrogans were detected in A. agrarius living in close proximity to humans in the metropolitan suburban areas. The results of this study indicate that rodent-borne bacteria may be present in wild rodents in the metropolitan suburban areas of ROK.

Isolation and molecular detection of duck plague virus for the development of vaccine seed

The present study was carried out for the isolation and molecular detection of duck plague virus (DPV) for the development of inactivated vaccine seed from the local outbreaks. A total of 12 suspected dead duck samples were collected from commercial farms and local market at Sunamganj, Netrokona and Mymensingh districts. Then, the samples were processed and prepared inocula were inoculated into 9-12 days old duck embryonated eggs. In duck embryonated eggs, several passages (3-4) were performed before infection into DEF cell culture. Presence of viral DNA was confirmed by PCR using the primer for DNA polymerase gene. After PCR confirmation, virus cultured in DEF cell was used for the preparation of formalin (0.12%) inactivated and oil based adjuvanted vaccine and was experimentally injected to 18 ducklings and 5 were kept as control. TCID50 of the selected virus for vaccine preparation was 108.70/ml. The mean passive haemagglutination assay (PHA) titre of sera of samples at 0 days, 7 days and 14 days post vaccination were 4.0±0, 14.22±1.78 and 44.44±4.4, respectively, which indicated significant (p<0.01) increase of antibody titre. Embryonated duck eggs and DEF cell culture are effective for virus isolation and on the basis of PHA test, it could also be suggested that the experimentally developed DP vaccine can be used successfully for the prevention of DP in Bangladesh.
 Asian Australas. J. Biosci. Biotechnol. 2018, 3 (1), 78-85

Protective effect of cytosine-phosphate-guanosine oligodeoxynucleotide against experimental mastitis induced by Cryptococcus neoformans infection in goats

The present study investigated the effect of synthetic non-methylated oligonucleotides containing Cytosine-phosphate-guanosine dinucleotides (Cytosine-phosphate-guanosine oligodeoxynucleotide) on caprine mastitis with Heat Killed Cryptococcus neoformans Ag. 20 healthy local breed does were used with weight ranging of 25-30 Kg and free of mastitis by examination via California Mastitis Test and Somatic Cell Count. The does were allotted into four equal groups, the first group (G1) was treated intramammary with 100μg/kg of Cytosine-phosphate-guanosine oligodeoxy nucleotide on fifth day postpartum in the right mammary gland while the left mammary gland served as control and were infused with sterile phosphate buffered saline. On day 8 postpartum repeat dosages of Cytosine-phosphate-guanosine oligodeoxynucleotide and phosphate buffered saline were infused respectively. On day 9 pp the right mammary gland was infused with 2ml of 2x108 cell/ml of Heat Killed Cryptococcus neoformans Ag. The second group (G2) was infused at day 9 postpartum with 2ml of 2x108 cell/ml of Heat Killed Cryptococcus neoformans Ag in the right mammary gland only. The third group (G3) was left until the challenge test done after one week of immunization in the G1 and G2, by inoculation of 2ml of 5x106 viable C. neoformans in the right mammary gland. The fourth group (G4) was kept as a control receiving 2ml of sterile PBS. Blood samples were collected at 0, 5, 10, 20, 30 and 40 days of the study, to determine the antibody titer by passive haemagglutination assay, while the cell mediated immunity was evaluated by detecting the goat Interferon Gamma by ELISA test and Phagocytic index. Also the cell mediated immunity was determined by delayed type hypersensitivity test after 21 days of immunization. The results showed a significant variation (P≤0.05) between vaccinated groups (G1 and G2) and the control. However, there was a significant increase (P≤0.05) of skin thickness shown after 48 hrs in the G1compared to G2. High level of Interferon Gamma concentration was noticed in the G1 as compared with other groups. Moreover, cell mediated immunity developed effectively in the G1 which was noted by a significant increase (P≤0.05) of phagocytic activity of polymorphonuclear cells. The high level of antibody titer was observed in the G1 as compared with other groups. In conclusion: These results suggest that vaccination with Cytosine-phosphate-guanosine oligodeoxynucleotide plus Heat Killed Cryptococcus neoformans Ag intramammary lead to a good protection of caprine mammary glands against C. neoformans mastitis.

Detection of clinically relevant platelet antibodies in the Asian population

BackgroundThe detection and identification of the clinically relevant platelet antibodies are important for the diagnosis and management of the affected patients with immune thrombocytopenia.AimsThe aim of this study was to investigate the characteristic of clinically relevant platelet antibodies in the Asian population, and to evaluate the ability of platelet immunology laboratories in Asia to detect and identify these platelet antibodies.MethodsTotal of 635 cases that were diagnosed and studied as NAITP, PTR and PTP by Asian platelet laboratories were reviewed for the clinical and experimental data from the publications.ResultsExcept the anti‐HLA and unknown‐specificity antibody, the most frequently identified platelet antibody was anti‐CD36 (18/635, 18·35%), and then anti‐HPA‐3 and anti‐HPA‐4 (each 5/635, 0·78%), and anti‐HPA‐5 (4/635, 0·62%). Only two cases of anti‐HPA‐1 antibodies (2/635, 0·31%) were reported. In 274 cases, including four cases contained anti‐HLA antibody, the laboratories could not identify the specificity of platelet antibodies. The methods of detection and identification of antiplatelet antibody, such as monoclonal antibody immobilization of platelet antigens (MAIPA), mixed passive hemagglutination assay (MPHA), platelet immunofluorescence test (PIFT), modified antigen‐capture ELISA (MACE) and solid‐phase red‐cell adherence (SPAA), have been used in Asian laboratories.ConclusionWith an increasingly heterogeneous patient population in Asia, diagnostic laboratories should be aware of the ethnic origin of a particular patient to consider the possibility of immunization to antigens. The most important clinical relevant platelet antibodies implicated in immune‐mediated thrombocytopenia among the Asian population are anti‐CD36, then anti‐HPA‐3, anti‐HPA‐4 and others.

Comparative immunogenicity of fowl cholera vaccine in Jinding ducks

This study compared the immunogenicity of alum-precipitated formalin-killed fowl cholera vaccines (BAU-FCV and LRI-FCV) in Jinding ducks. The ducks were divided into three groups (A = 14, B = 14, C = 12). Group A was inoculated with BAU- FCV 0.5 mL and group B with LRI- FCV 1.0 mL intramuscularly (im) at the age of six weeks and group C served as unvaccinated control. Booster vaccination was administered similarly at 11 weeks of age in groups A and B. Challenge infection was given to all birds two weeks after booster vaccination. Passive Haemagglutination Assay (PHA) antibody titres in group A were 59.4 ± 4.6 21 days after primary vaccination, 137.1 ± 21.8 15 days after booster vaccination, 100.6 ± 12.9 21 days after booster vaccination, and 256.0 ± 48.4 15 days after challenge. In group B, titres were 50.3 ± 6.5, 118.9 ± 9.1, 91.4 ± 12.9, 237.7 ± 51.7, respectively, whereas titres in group C remained at ?4.0 ± 0.0. The antibody titres were insignificant when compared between pre-vaccination and 21 days after primary vaccination in both vaccinated groups (A and B). PHA antibody titres of groups A were significantly (P < 0.0001) increased at 15 days after booster and in case of group B the antibody titres were insignificant. At 15 days after challenge the antibody titres were highly significant in both groups (A and B). There was no significant difference between the two vaccinated groups. Following challenge infection with virulent Pasteurella multocida 88.9% of birds vaccinated with BAU-FCV, and 77.8% of birds vaccinated with LRI-FCV survived, while all unvaccinated birds died. Both vaccines were safe and effective. DOI: http://dx.doi.org/10.3329/bvet.v30i2.18253 Bangl. vet. 2013. Vol. 30, No. 2, 41-45

Diagnosis of scrub typhus: introduction of the immunochromatographic test in Korea

Diagnosis of scrub typhus: introduction of the immunochromatographic test in Korea

HBc抗体測定系におけるPHA法（マイセルanti-rHBc）とCLIA法（アーキテクト・HBc II）の比較

We aimed to evaluate the correlation between two methods of the detection of antibody to hepatitis B core antigen (anti-HBc); chemiluminescent immunoassay (CLIA; Architect®Anti-HBc II) and passive hemagglutination assay (PHA; Mycell®anti-rHBc). 249 positive cases and 436 negative cases among 685 employees were determined. The percent agreement between CLIA and PHA was 96.4%. Positive values by PHA were distributed from 26 to 222 fold, while those of CLIA from 1.0 to 26.6 S/CO. High titers more than 10 S/CO by CLIA were equivalent to over 210 fold by PHA. While in low titers of anti-HBc PHA was slightly lower in sensitivity than CLIA, PHA is more quantitative than CLIA in high titers of anti-HBc.

Seroprevalence ofLeptospirosis in Human beings and Animals in Central and NorthKerala

A study was undertaken to assess the prevalence of leptospirosis in animals and man in Central and North Kerala. Five hundred and one sera samples collected from dogs, cattle, pigs, rodents (bandicoots and rats) and human beings were serologically tested for leptospiral antibodies by Microscopic Agglutination Test (MAT) and Passive Haemagglutination Assay (PHA). The MAT detected a prevalence of 36.36 per cent in dogs, 47 per cent in cattle, 23.80 per cent in pigs, 21.42 per cent in rodents and 54.54 per cent in human beings. Passive Haemagglutination Assay detected a prevalence of 50.41 per cent in canine, 23 per cent in bovine, 19.04 per cent in porcine, 26.19 per cent in murine and 42.85 per cent in human sera. The most predominant serovar infecting dogs, pigs and rodents was identified as Leptospira interrogans serovar Pomona. Humans showed maximum prevalence to serovar Australis followed by Pomona while cattle showed the highest prevalence to serovar Hardjo of serogroup Sejroe. High prevalence of leptospiral antibodies in apparently healthy animals like cattle proves the major role played by animals in the dissemination of infection in animal

Horizontal transmission of bovine leukemia virus from lymphocytotic cattle, and beneficial effects of insect vector control

Bovine leukaemia virus (BLV) causes enzootic bovine leukosis (EBL) in cattle and represents a serious problem in Japanese meat and dairy industries (Ministry of Agriculture, Forestry and Fisheries). BLV can...

Extraction of calicomacropeptide protein from cheese whey and its use as an antibacterial agent against Escherichia coli and Staphylococcus aureus in children.

This study focused on the extracted of protein Glycomacropeptide of soft white cheese whey and factory using rennet (chymosin) and studying of its effect outside the body's animals in vetro and within the body of the animal in vivo, the results were as follows: pathological bacteria antigens used with Glycomacropeptide in passive haemagglutination assay and showed that agglutination was 1:256 with LPS isolated from bacteria E. coli. The passive haemagglutination assay also showed that agglutination was 1:64 with LPS isolated from bacteria Staph. aureus Glycomacropeptide protein proved the inhibition activity the outsideof the animal's body (in vitro) against bacterial isolates of E. coli and , which causes diarrhea and inflammatory intestine disease and Staph. aureus bacteria in children by using Nutreint Broth media and using a Spectrophotometer and different concentrations (0.1, 0.6, 1.1, 6.3) mg / ml had a higher inhibition concentration of 6.3 followed by 1.1. Glycomacropeptide protein proved effectiveness inhibitory, within the body of mice (In vivo) against bacteria E. coli and Staph. aureus by studying their effect on red blood cells and white blood cell as it worked to increase

English

The commercial production of purified tetanus toxoid mainly depends on the effective separation of the bacterial toxin and toxoid from large volumes of fermentation broth of Clostridium tetani (Harvard 49205) vaccine strain. Tangential flow or cross-flow filtration system was used as rapid drive in the processing of immunobiological assays of tetanus toxin. Tetanus toxoid was prepared by detoxifying the culture filtrates of C. tetani and further purified by ultrafiltration, salt fractionation and adsorption onto aluminium phosphate. Present study deals with the separation of tetanus toxins using a microporous membrane (0.22 µm) and concentration of tetanus toxoids using an ultrafiltration membrane (30 kDa, NMWL pore size) with operational variables like average trans-membrane pressure (ATP), cross flow rate, flux. Under the best conditions, >96% recovery was achieved. Additionally, potency control of 10 batches of tetanus toxoid, prepared from the filtered toxins/toxoid lots by microporous tangential flow filtration system, was evaluated by in vitro passive haemagglutination (PHA) assay and the results obtained in the in vitro PHA were compared with in vivo toxin neutralization (TN) test. An excellent correlation between in vitro test and in vivo TN test was observed by Spearman’s correlation coefficient. It reveals that the process development in which employing available equipment and the in vitro PHA is a promising alternative to the toxic TN test in the potency assay of tetanus vaccine. Key words: Tetanus toxin, Seitz filtration, tangential flow filtration, microfiltration module, flux, tetanus toxoid, immunogenicity test.

Immune response and protective potential following vaccination against Newcastle disease virus and fowl cholera in Naked neck chickens

Humoral immune responses to Newcastle Disease Virus (NDV) and Bangladesh Agricultural University (BAU) Fowl cholera (BAUFC) vaccines were evaluated in naked neck chickens (NNC). Ten birds were vaccinated with Baby Chick Ranikhet Disease Virus (BCRDV) at Day 7 through intra-ocular route and with Ranikhet Disease Virus (RDV) at day 35 of age through intramuscular route. Serum antibodies were measured by Haemagglutination Inhibition test. Two weeks after final immunization all birds were challenged with virulent field isolate of NDV where all vaccinated birds survived without illness during ten days, and all ten control birds died. Ten birds were vaccinated with BAUFC vaccine at Day 42 and 70 according to the Manufacturer’s instruction, which induced detectable levels of antibody titre as determined by Passive Haemagglutination Assay (PHA) test. Eight vaccinated birds survived following challenge with virulent fowl cholera isolate two weeks after final vaccination and all ten control birds died. DOI: http://dx.doi.org/10.3329/bvet.v29i2.14342 Bangl. vet. 2012. Vol. 29, No. 2, 49-55

HUMORAL IMMUNE RESPONSE TO FOWL CHOLERA VACCINE IN DIFFERENT BREEDS OF COMMERCIAL BIRDS

Fowl cholera is a highly contagious and economically important disease of poultry worldwide. Control of fowl cholera depends mainly on vaccination throughout the world including Bangladesh. Therefore, the objective of the study was to determine the antibody titre following vaccination with fowl cholera vaccine in different breeds of commercial birds including Aseel and its F1 crosses. The study was conducted at Bangladesh Agricultural University Poultry Farm during the period from March to December 2011. A total of 37 birds of four types of breeds (Synthetic - 10, White Rock - 10, Aseel - 7 and Aseel×Rhode Island Red - 10) of both sex and 17 weeks old were used in this trial. Primary and booster vaccination were done in all the birds of four groups with fowl cholera vaccine (BAU-FCV) @ 0.5 ml/bird IM at 20 weeks and 26 weeks of age, respectively. Blood samples were collected at different occasions of vaccination. The immune responses (serum antibody titre) were determined by using passive haemagglutination assay (PHA). All the four groups of vaccinated birds induced significantly higher humoral immune response after primary and booster vaccination. However, no significant differences were observed in antibody titres between breeds on different occasions of vaccination. Of the four groups, antibody titres were slightly higher in breeds of Aseel×RIR and White Rock birds than other two breeds. It appears from the study that breed variation has no significant effect on immune response to fowl cholera vaccine.DOI: http://dx.doi.org/10.3329/bjvm.v9i2.13453

Antigenic Drift of Orientia tsutsugamushi in South Korea as Identified by the Sequence Analysis of a 56-kDa Protein-Encoding Gene

This study was performed to determine the nationwide antigenic diversity of Orientia tsutsugamushi in South Korea. Sequence analysis was performed around variable domains I and II of a 56-kDa protein-encoding gene. We used eschar to overcome the disadvantages of conventional serotyping. The serological passive hemagglutination assay (PHA) was assessed based on the genotyping results. We analyzed 153 isolates from scrub typhus patients in major endemic areas and found that Boryong was the major strain (68.6%). New strains were also identified: Taguchi (19.6%), Kanda/Kawasaki (9.2%), and UAP7 (1.3%). PHA yielded significantly fewer positive results among Kawasaki strains (P < 0.001), which are not included in the PHA antigen panel. In South Korea, Boryong was still the predominant strain, but the sequence analysis identified new changes in minor strains (30.1%). This antigenic drift had a negative effect on the PHA results. Periodic surveillance of the contemporary strains using sequence analysis is needed.

Allergic transfusion reactions from blood components donated by IgA‐deficient donors with and without anti‐IgA: a comparative retrospective study

IgA deficiency is common (1/500) and up to 40% of affected individuals will develop anti-IgA. A few studies suggested that passive transfusion of anti-IgA was not associated with an increased risk of allergic reactions. This study was designed to assess the safety of transfusing blood components containing anti-IgA. IgA-deficient blood donors with and without anti-IgA were identified from Héma-Québec's (HQ) computerized database. IgA deficiency was confirmed by an ELISA method and the presence of anti-IgA by a passive hemagglutination assay. Blood donations from IgA-deficient donors issued to hospitals between March 1999 and December 2004 were retrieved. Medical charts of recipients were reviewed for the occurrence of a suspected transfusion reaction. Presence and nature of transfusion reactions were assessed blindly by an adjudicating committee. A total of 323 IgA-deficient blood products were issued by HQ to 55 hospitals. Of these, 48 agreed to participate [315 blood products (97.5%)]. A total of 272 products were transfused: 174 contained anti-IgA, and 98 did not. Only two minor allergic reactions occurred in each group. Incidence of allergic reactions was 1.15% in the anti-IgA group and 2.04% in the group without anti-IgA (P = 0.91). There was no anaphylactic reaction in either group. This study indicates that the proportion of allergic reactions does not appear to be greater in recipients of blood components containing anti-IgA compared to recipients of non-anti-IgA-containing components. Allowing donations from IgA-deficient donors with anti-IgA may therefore be contemplated.

External Quality Assessment for the Determination of Diphtheria Antitoxin in Human Serum

Accurate determination of diphtheria toxin antibodies is of value in determining the rates of immunity within broad populations or the immune status of individuals who may be at risk of infection, by assessing responses to vaccination and immunization schedule efficacy. Here we report the results of an external quality assessment (EQA) study for diphtheria serology, performed within the dedicated surveillance network DIPNET. Twelve national laboratories from 11 European countries participated by testing a standard panel of 150 sera using their current routine method: Vero cell neutralization test (NT), double-antigen enzyme-linked immunosorbent assay (ELISA; DAE), dual double-antigen time-resolved fluorescence immunoassay (dDA-DELFIA), passive hemagglutination assay (PHA), toxin binding inhibition assay (ToBI), and in-house or commercial ELISAs. The objective of the study was not to identify the best assay, as the advantages and drawbacks of methods used were known, but to verify if laboratories using their routine method would have categorized (as negative, equivocal, or positive) a serum sample in the same way. The performance of each laboratory was determined by comparing its results on a quantitative and qualitative basis to NT results from a single reference laboratory, as this test is considered the in vitro "gold standard." The performance of laboratories using NT was generally very good, while the laboratories' performance using other in vitro methods was variable. Laboratories using ELISA and PHA performed less well than those using DAE, dDA-DELFIA, or ToBI. EQA is important for both laboratories that use in vitro nonstandardized methods and those that use commercial ELISA kits.

Screening of Canadian Blood Services donors for severe immunoglobulin A deficiency

Immunoglobulin A (IgA)-deficient patients with antibodies to IgA require transfusions with IgA-deficient blood components to either avoid or reduce the frequency of serious adverse reactions. To supply compatible blood components for these individuals, the Canadian Blood Services (CBS) National Testing Laboratory must initially screen and subsequently identify, after confirmatory testing at the American Red Cross (ARC), donors severely deficient in IgA (<0.05 mg/dL). The Ouchterlony double immunodiffusion assay was used as an initial screen at CBS to identify IgA-deficient donors (test sensitivity 2-4 mg/dL). Sample aliquots from these donors were then sent to the ARC for confirmatory testing using an enzyme-linked immunosorbent assay method for severe IgA deficiency (<0.05 mg/dL) and a passive hemagglutination assay to detect anti-IgA. From November 2007 to December 2008, of 54,594 samples screened initially at CBS there were 137 samples (0.251%) identified as possibly IgA deficient. Of these 137, there were 100 reports returned from ARC confirming severe IgA deficiency in 65 donors (25 female, 40 male) without detectable anti-IgA and in 35 donors (18 female, 17 male) with anti-IgA. The remaining 37 donors had IgA levels of more than 0.05 mg/dL. Results from the ARC confirmed a frequency of 1 in 546 in the CBS' blood donor population for severe IgA deficiency (<0.05 mg/dL), 1 in 840 for those without anti-IgA, and 1 in 1560 for those with antibody. Donors repeatedly confirmed as severely IgA deficient without anti-IgA were considered eligible for the CBS IgA-deficient donor registry program.

A serosurvey of Orientia tsutsugamushi from patients with scrub typhus

AbstractMany countries where scrub typhus is endemic use their own cutoff values for antibody titres to differentiate between cured cases and current infections. To establish an antibody titre cutoff value, one needs to investigate the seroprevalence in endemic areas, and the duration of the increase in titre after complete cure. We conducted a follow-up study of anti-Orientia tsutsugamushi antibody titres using indirect immunofluorescence assays (IFA) and passive haemagglutination assays (PHA) in patients with scrub typhus. After the onset of symptoms, IgM antibody titres increased gradually over 2–3 weeks, peaked at about 4 weeks, and started to decrease rapidly between 4 and 5 weeks. At 1-year follow-up, the median IgM value was 1:10. Out of 77 patients who were tested at that time, 36 (47%) had IgM titres ≥1:20, and none had titres exceeding 1:80. Over the first 2 weeks, IgG antibody titres increased sharply, peaked at about 4 weeks and decreased rather gradually thereafter, with a median titre of 1:128 maintained up to the 18th month. At 1-year follow-up, five out of 77 patients (6.5%) had titres ≥1:1,024 and 57% had titres ≥1:128. Based on these results, a cutoff value of ≥1:160 for IgM antibody should differentiate between previous and current infections in endemic areas such as Korea and Japan, where scrub typhus occurs mainly in the autumn.

The first case of alloantibody against human platelet antigen‐15b in Japan: possible alloimmunization by a hydatidiform mole

The involvement of the human platelet antigen (HPA)-15 system in neonatal alloimmune thrombocytopenia (NAIT) has been reported in various populations, but not in the Japanese population. In Japan, the mixed passive hemagglutination assay (MPHA) is used for detection of HPA alloantibodies. However, most of the reported cases of HPA-15 incompatibility are based on the monoclonal antibody immobilization of platelet antigen (MAIPA) assay or immunoprecipitation; thus there is a possibility that HPA-15 alloantibodies are not efficiently detected by the MPHA, and currently, the causative antibody is not detectable in approximately half of the suspected NAIT cases in Japan. We examined the sera of mothers from NAIT cases, previously with undetected HPA antibodies by MPHA, using the MAIPA technique. Sera from 90 mothers of suspected NAIT were tested by MAIPA for the presence of anti-HPA-15 alloantibodies. Anti-HPA-15b was detected in one case. This case was a mother in the first pregnancy diagnosed as hydatid mole-coexisting fetus, and the baby was born with suspected NAIT. The familial analysis revealed compatibility of HPA-15 genotype between the mother and the baby (both HPA-15a/a), but incompatibility with the paternal one (HPA-15a/b). The hydatid mole's tissue was genotyped as HPA-15b positive. Besides anti-HPA-15b, maternal sera contain strong HLA Class I antibody Here we reported the first case of anti-HPA-15 in Japan. Alloimmunization against the hydatid mole seems to be responsible for the production of HPA-15b alloantibody. This antibody, however, did not apparently involve in the development of NAIT of the newborn, the coexisting anti-HLA Class I being the possible cause.