Serotyping and Enzyme Characterization of Pasteurella haemolytica and Pasteurella multocida Isolates Recovered from Pneumonic Lungs of Stressed Feeder Calves

Ninety-one isolates of Pasteurella multocida (Pm) and 124 of Pasteurella haemolytica (Ph) were recovered from the lungs of calves that died of bovine respiratory tract disease (BRTD). Nine Pm enzyme profiles (A through I) and 9 Ph enzyme profiles (J through R) were determined for the Pasteurella isolates. The Pm isolates were relatively evenly divided among the enzyme profiles, with one exception, profile I. The Ph isolates were not evenly distributed among the profiles. Fifty of the 91 Pm isolates were serotyped. Forty-two Pm isolates were positive for capsule type A, and 8 were untypable. Five somatic type antigen profiles (3; 3,4; 3,7; 3,4,7; and 4) were identified among the 50 serotyped Pm isolates; one isolate was untypable. The Ph isolates were further divided through serotyping and grouped as follows: 74 (60%) Pasteurella haemolytica A1 (PhA1), 12 (10%) PhA2, 4 (3%) PhA5, and 34 (27%) PhA6. Eighty-one percent of the Ph serotypes were clustered in the M and N enzyme profile. The P enzyme profile was almost unique to PhA2 (8 of 12, 67% of PhA2 isolates). Results of this study indicate a need to collect more data on Ph serotypes at the state veterinary diagnostic laboratories. Received: 29 August 1996 / Accepted: 15 October 1996     

Cross-Protection Studies with Three Serotypes of Pasteurella haemolytica in the Goat Model

Cross-protection studies employing three serotypes of Pasteurella haemolytica (Ph) were performed in goats, with challenge exposure by transthoracic injection. Indirect hemagglutination (IHA) serum titers showed that the herd had been naturally infected with Ph biovar A, serovar 2 (PhA2) prior to the study. Sixty-four weanling male Spanish goats were randomly allotted to 16 groups. Fifteen goats were given two transthoracic injections into the lungs 21 days apart with live Pasteurella haemolytica biovar A, serovar 1 (PhA1) in agar beads. Fifteen goats were given two transthoracic injections into the lungs 21 days apart with live PhA2 in agar beads. Sixteen goats were given two transthoracic injections into the lungs 21 days apart with live P. haemolytica biovar A, serovar 6 (PhA6) in agar beads. Eighteen control (CON) goats were given two transthoracic injections into the lungs 21 days apart with agar beads alone. Fourteen days after the second injection, goats were challenge-exposed to either live PhA1, PhA2, or PhA6 by transthoracic injection into the lung, and 4 days later, all goats were euthanatized and necropsied. Serum antibody to P. haemolytica antigens was measured throughout the experiment. Mean volumes of consolidated lung tissue for the CON goats challenged with PhA1, PhA2, and PhA6 were 28.29 cm³, 8.36 cm³, and 16.29 cm³, respectively. Mean volumes of consolidated lung tissue for the PhA1-immunized goats challenged with PhA1, PhA2, and PhA6 were 4.38 cm³, 0.25 cm³, and 1.90 cm³, respectively. Mean volumes of consolidated lung tissue for the PhA2-immunized goats challenged with PhA1, PhA2, and PhA6 were 9.68 cm³, 0.05 cm³, and 3.39 cm³, respectively. Mean volumes of consolidated lung tissue for the PhA6-immunized goats challenged with PhA1, PhA2, and PhA6 were 14.05 cm³, 1.27 cm³, and 4.53 cm³, respectively. These data demonstrate protection in immunized goats challenged with the homologous serotype of P. haemolytica. PhA1-immunized animals were protected against serotype 2 challenge as well as against serotype 6 challenge. PhA2-immunized animals were not protected against serotype 1 challenge, but were protected against transthoracic PhA6 challenge. PhA6-immunized animals were not protected against serotype 1 challenge, but were protected against transthoracic PhA2 challenge. There appears to be some cross-protection among the P. haemolytica serotypes, and this fact should be taken into consideration when developing vaccines against this organism. Received: 13 June 1997 / Accepted: 6 October 1997     

Extracellular neuraminidase production by Pasteurella species isolated from infected animals

A total of 721 field isolates of various Pasteurella species (haemolytica, multocida, and testudinis) from various regions of the United States were examined for extracellular neuraminidase production. All strains were grown and tested in the same way. Included were 372 P. haemolytica serotype 1 isolates, 181 P. haemolytica serotype 2 isolates, 63 P. haemolytica serotype 6 isolates, 101 Pasteurella multocida isolates, and 4 Pasteurella testudinis isolates. All Pasteurella species examined produced the enzyme. The data revealed the following: (1) Several transfers of P. haemolytica strains on blood agar medium did not cause a decrease in enzyme activity. (2) P. haemolytica serotypes 2 and 6 produce more neuraminidase than P. haemolytica serotype 1, P. multocida, and P. testudinis isolates. (3) There was no apparent change in neuraminidase production by P. haemolytica serotypes 1 and 2 obtained from the same animal taken on different days in the feedyard. (4) There was no significant change in neuraminidase production by P. haemolytica serotype 2 isolates taken from the same animal at the auction market and later at the feedyard.     

In vivo production of neuraminidase by Pasteurella multocida A:3 in goats after transthoracic challenge

Six goats were injected transthoracically with live Pasteurella multocida A:3 to examine if an extracellular enzyme, neuraminidase, was produced in vivo during infection with this organism. The principal group of goats (n = 6) each received 1 ml of live 7.5 × 10⁴ cfu of P. multocida mixed with polyacrylate beads transthoracically in the left lung on day 0 and 1 ml of live P. multocida (2.2 × 10⁸ cfu) mixed with polyacrylate beads transthoracically in the left lung on day 22. Six goats were used as negative controls and received 0.3 g of polyacrylate beads subcutaneously in the right flank on days 0 and 22. Serum was obtained from all animals on days 0, 7, 14, 22, 29, and 36. Preimmune sera from all animals showed no detectable antibody to P. multocida A:3 neuraminidase in an enzyme neutralization assay. None of the sera from the negative control animals demonstrated a significant antibody titer against the P. multocida A:3 neuraminidase. On day 36, serum samples from the six infected animals possessed complete enzyme-neutralizing activity. Anti-neuraminidase antibody could be detected as early as day 14 in the infected animals. These data show that neuraminidase is produced in vivo during an active P. multocida A:3 lobar infection. Received: 16 March 1996 / Accepted: 19 April 1996     

Pasteurella haemolytica Ultraviolet-Irradiated Vaccine by Parenteral and Aerosol Routes Compared in the Goat Model

Positive control 1 (PC1) (n = 9) goats were injected transthoracically into the left lung with live Pasteurella haemolytica biovar A, serovar 1 (PhA1) in polyacrylate (PA) beads on days 0 and 21. Positive control 2 (PC2) (n = 6) goats were nebulized with live PhA1 and PA beads on days 0 and 21. Negative control (NC) goats (n = 6) were each injected transthoracically into the left lung with PA beads alone on days 0 and 21. Four groups (n = 6) were administered PA beads mixed with ultraviolet (UV) killed PhA1 on days 0 and 21. The treatment doses of bacteria for these groups were principal group 1 (PR1) injected into the left lung (7.7 × 10¹⁰ cfu); PR2, 7.7 × 10¹⁰ UV-killed PhA1 injected subcutaneously (SC); PR3, 7.7 × 10¹⁰ UV-killed PhA1 injected SC only on day 21; PR4, nebulized with PA beads mixed with 5.6 × 10¹⁰ cfu of UV-killed PhA1; and PR5, nebulized with PA beads mixed with 5 × 10⁸ cfu of UV-killed PhA1. All goats were challenged transthoracically in the right lung with 1 × 10⁸ cfu of live PhA1 on day 42 and necropsied on day 46. The sizes of consolidated lung lesions at the challenge site were used as a measure of immunity. The data show that the introduction of live PhA1 into the lungs of goats, either by injection or aerosolization, offers excellent protection against a subsequent homologous challenge. The data also demonstrate that two transthoracic injections (21 days apart) of UV-killed PhA1 (PR1), and subcutaneous injection of UV-killed PhA1(PR2) also offer excellent protection against a subsequent homologous live PhA1 challenge. One SC injection of UV-killed PhA1 (PR3) appears to offer only partial protection against a subsequent homologous live PhA1 challenge. Inhalation of UV-killed PhA1 mixed with PA beads (PR4 and PR5) induced no protection in goats against a subsequent live PhA1 transthoracic challenge. Received: 3 February 1998 / Accepted: 18 March 1998     

Detection of Coronavirus 229E Antibody by Indirect Hemagglutination

Tannic-acid treated sheep erythrocytes (fresh or glutaraldehyde preserved) were sensitized with 229E antigens from human embryonic lung (RU-1) cell cultures. Indirect hemagglutination (IHA) antigen titers in 229E-infected cell cultures paralleled virus infectivity and complement fixation (CF) antigen titers. The identity of the IHA antigen was confirmed by testing extracts from inoculated and control cell cultures for ability to inhibit IHA. Also, significant increases in IHA antibody were demonstrated with acute and convalescent serum pairs from patients with proven 229E infections. A comparison of IHA, neutralization and CF titers for 229E antibodies was made on human sera drawn from different populations. The IHA and neutralization results were in agreement on 93% of the 129 sera found to be positive by at least one of three tests. The number of antibody titers detected by the CF test was insufficient to permit comparison. Hyperimmune sera from animals immunized with OC 43 did not react with 229E by IHA. Also no increase in IHA antibody was demonstrated with acute and convalescent serum pairs from patients with seroconversions to OC 43. These findings suggest that the IHA test provides (i) a rapid and sensitive method for serodiagnosis of 229E infections and (ii) a simple and inexpensive method for seroepidemiological studies.     

Evaluation of an indirect hemagglutination inhibition technique for identifying antibody in animals experimentally and naturally exposed to fungi

Rabbits were exposed to aerosols containing spores of Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, or of a Penicillium sp. Sera from these rabbits were tested by indirect hemagglutination (IHA) and by IHA inhibition. The serologic reactions with the rabbit sera were compared to reactions with sera from cattle naturally exposed to airborne microorganisms. By three months of age, most cattle had positive IHA reactions to A. fumigatus and Penicillium antigens. The IHA inhibition tests indicated that antibody production in 12 of the 20 cattle probably resulted from exposure to A. flavus. One calf reacted as if sensitized by A. niger. Two were totally nonreactive. Five of the cattle had reactions that were not identifiable relative to the reactions in rabbits.Purchased by U.S. Department of Agriculture for Official Use.     

Indirect haemagglutination (IHA) test in the serodiagnosis of amoebiasis

Among 72 patients clinically suspected of Entamoeba histolytica (E. histolytica) infections, 39 positive cases (54%) were detected serologically by the indirect hemagglutination (IHA) test. Parasitologically, microscopic examination of three consecutive stool specimens from all these patients indicated positivity for E. histolytica cysts and or trophozoites in 10 of the patients with IHA antibody titers greater than or equal to 1:128, which is of clinical significance. Another 2 patients were parasitologically positive but showed low IHA antibody titres (1:32-1:64); follow up indicated response to treatment with metronidazole. The highest serological positivity (100%) were detected in patients with liver abscess, all were clinically proven cases of extra-intestinal amoebiasis. IHA antibody levels of clinical significance were seen in all four patients with chronic dysentery with parasitological evidence of E. histolytica in their stools. In a group of patients with abdominal pain nine positives were detected serologically, four of which were positively diagnosed concurrently by parasitology; the remaining five patient's sera showed high IHA antibody titres with absence of cysts or trophozoites in stools, indicative possibly of persistence of antibodies from past infection. The serologic determination of E. histolytica IHA antibodies in a control group consisting of normal healthy school children and adults of both sexes without any clinical evidence of amoebiasis showed the absence of any positive titres of clinical significance; low titres (1:32-1:64) were detected in 5.2% of 232 sera tested. Parasitological examination of three consecutive stool specimens from all individuals in the control group showed the presence of cysts of E. histolytica in just two among 232 tested (0.9%).     

AHL-Deficient Mutants of Burkholderia ambifaria BC-F Have Decreased Antifungal Activity

The objective was to determine whether the inhalation of large quantities of feedyard dust predisposed the animals to pulmonary bacterial proliferation. Two control groups, C1 and C2, did not receive dust treatments, and two principal groups (P1 and P2) received a total of 14 dust treatments each. The C1 and P1 groups of goats each received a transthoracic challenge of live Mannheimia haemolytica (4 × 10⁶ colony forming units, CFU) The C2 and P2 groups of goats each received a transthoracic challenge of live Pasteurella multocida (1.0 × 10⁶ CFU/goat). The results showed that dusted animals had fever when compared with non-dusted controls. In addition, dusted animals demonstrated a leukocytosis with neutrophilia after the first dust treatment that was not sustainable. Finally, dusted animals demonstrated pulmonary clearance of two potential bacterial pathogens that was not significantly different from that shown by control (not dusted) animals. Received: 26 March 2002 / Accepted: 24 May 2002     

Typing Herpesvirus hominis Antibodies and Isolates by Inhibition of the Indirect Hemagglutination Reaction

Inhibition of the indirect hemagglutination reaction (IHA inhibition) was compared to several other methods for type-specific identification of Herpesvirus hominis (HVH) antibodies and isolates. The method appears to have the greatest value for typing antibodies for HVH type 1 and HVH type 2 in human sera; identification of antibody type was relatively simple and results were definitive. The IHA-inhibition test permitted serological diagnosis of HVH type 2 infection in three young adults with meningoencephalitis, thus extending the mounting evidence that nervous system involvement with this virus type is not limited to neonatal infections. II/I indexes of neutralizing or IHA antibody gave an accurate indication of the presence of HVH type 2 antibody in those sera containing type 2 antibody by IHA inhibition, but they indicated the presence of HVH type 2 antibody in one-half or more of the sera shown to contain only HVH type 1 antibody by IHA inhibition. For typing HVH isolates, the IHA-inhibition test gave results identical to those obtained by direct fluorescent-antibody staining using cross-absorbed conjugates, but the IHA-inhibition test was much more cumbersome and time-consuming to perform than was direct fluorescent-antibody staining. A microneutralization technique for virus typing also gave results identical to those obtained with direct fluorescent-antibody staining and IHA inhibition. However, typing HVH isolates by plaque size or the differential effect of incubation temperature was found to be less definitive and accurate.     

Serological Diagnosis of Human Melioidosis with Indirect Hemagglutination and Complement Fixation Tests

An indirect hemagglutination (IHA) test and a complement fixation (CF) test were evaluated from test results on sera from 212 human melioidosis patients of which 119 were culturally proved cases. Significant antibody titers (IHA titers of 1:40 or greater and CF titers of 1:4 or greater) were demonstrated with either test in all except five patients. IHA and CF titers ranged as high as 1:20,480 and 1:1,024, respectively. Antibodies were usually demonstrated by both tests 1 week after onset of disease. Transient seronegative reactions during the course of disease were seen in sera of approximately 19% of the patients with either IHA and CF but rarely with both tests. High titers in either test were obtained by the third week of disease and reached maximum levels in 4 to 5 months. Titers usually were detectable for 9 or more months. Antibodies were detected by IHA and CF tests in 80 to 100% of the sera obtained at various time intervals from 9 months to 2 or more years after disease onset. Antibody persistence occurred in patients who had a short disease course, as well as in patients with prolonged, complicated infections. The IHA test had excellent specificity when evaluated with normal human sera and diverse antimicrobial sera from hyperimmunized rabbits and human patients. The CF antigen appeared to contain common antigens with some but not all types of Pseudomonas aeruginosa. The specificity of the CF antigen could be enhanced without appreciable effect on its sensitivity by use of a titer of 1:8 in lieu of 1:4 as a criterion for a significant reaction. Either test could be used advantageously for the laboratory diagnosis of melioidosis.     

Neuraminidase fromPasteurella haemolytica

A soluble extracellular antigen produced byPasteurella haemolytica serotype 1 possesses neuraminidase activity. The metal ions Mn²⁺, Mg²⁺, and Ca²⁺ stimulate enzyme activity, while the heavy metal ions Hg²⁺ and Fe³⁺ inhibit neuraminidase activity. Extensive dialysis of the enzyme with 50 mM ethylenediaminetetraacetic acid does not result in loss of enzyme activity. Antiserum prepared againstPasteurella haemolytica serotype 1 inhibits neuraminidase activity 2.0- to 2.7-fold, suggesting that neuraminidase is part of the antigenic complex. Initial rate kinetics of neuraminidase reveals that the Michaelis constant for fetuin is 3.84 mg/ml (96 M) and the maximal velocity (V _max) is 0.53 mmol/min/mg of protein.     

PmST3 from <Emphasis Type="Italic">Pasteurella multocida</Emphasis> encoded by <Emphasis Type="Italic">Pm1174</Emphasis> gene is a monofunctional α2–3-sialyltransferase

Pasteurella multocida (Pm) strain Pm70 has three putative sialyltransferase genes including Pm0188, Pm0508, and Pm1174. A Pm0188 gene homolog in Pm strain P-1059 encodes a multifunctional α2–3-sialyltransferase, PmST1, that prefers oligosaccharide acceptors. A Pm0508 gene homolog in the same strain encodes a monofunctional sialyltransferase PmST2 that prefers glycolipid acceptors. Here, we report that the third sialyltransferase from Pm (PmST3) encoded by gene Pm1174 in strain Pm70 is a monofunctional α2–3-sialyltransferase that can use both oligosaccharides and glycolipids as efficient acceptors. Despite the existence of both Pm0188 and Pm0508 gene homologs encoding PmST1 and PmST2, respectively, in Pm strain P-1059, a Pm1174 gene homolog appears to be absent from Pm strains P-1059 and P-934. PmST3 was successfully obtained by cloning and expression using a synthetic gene of Pm1174 with codons optimized for Escherichia coli expression system as the DNA template for polymer chain reactions. Truncation of 35 amino acid residues from the carboxyl terminus was shown to improve the expression of a soluble and active enzyme in E. coli as a C-His₆-tagged fusion protein. This sialidase-free monofunctional α2–3-sialyltransferase is a useful tool for synthesizing sialylated oligosaccharides and glycolipids.     

Serologic test for antibody to Sarcocystis in cattle.

Soluble antigen was prepared from Sarcocystis zoites obtained from heart muscle of a bovine inoculated with sporocysts from canine feces and killed 120 days after infection. The antigen was used in an indirect hemagglutination (IHA) test and an agar gel diffusion test to detect antibody to Sarcocystis in experimentally infected cattle. IHA serum titers began to rise 30 to 45 days after infection and reached levels up to 1:39,000 90 days after infection. Sera collected under field conditions from 21 dairy cows had IHA titers ranging from 1:54 to 1:486. Since all cows appeared in good health, titers of 1:486 or less can probably be considered nonsignificant with regard to diagnosis of clinical disease. No positive Sarcocystis IHA titers were obtained with human sera previously found to be IHA positive for toxoplasma, indicating a lack of cross reactivity between antigens. Precipitins in the agar gel diffusion test appeared 30 days postinoculation and became very pronounced at 65 to 90 days.     

鼠疫菌F1抗体/抗原酶联免疫诊断试剂盒的应用评价

目的对兰州生物制品研究所有限责任公司研制的鼠疫菌F1抗体酶联免疫诊断试剂盒和鼠疫菌F1抗原酶联免疫诊断试剂盒进行临床应用评价。方法采用双抗原/抗体夹心酶联免疫吸附试验(ELISA)、间接血球凝集试验(IHA)、胶体金免疫层析试验(GICA)3种方法的诊断试剂对比检测云南省地方病防治所中心实验室保藏的和现场采集的血清样品和脏器样品,对血清样品做鼠疫菌F1抗体检测,对脏器样品做鼠疫菌F1抗原检测。结果在358份血清样品中,ELISA试剂检出F1抗体阳性52份(14.52%),IHA试剂检出阳性37份(10.34%),GICA试剂检出阳性45份(12.57%)。ELISA与IHA试剂的符合率为95.23%,与GICA试剂的符合率为96.92%。经统计学χ2检验,ELISA试剂检出F1抗体阳性率高于IHA试剂(χ2=11.53,P=0.000 7),与GICA试剂检出的差异无统计学意义(χ2=3.27,P=0.070 4)。进一步分析滴度差值频数,ELISA试剂检测人血清的敏感性高于IHA试剂的样品占87.5%。在117份脏器样品中,3种试剂均检出F1抗原阳性15份(12.82%),符合率100%。滴度差值频数比较,ELISA试剂检测敏感性高于反向间接血球凝集试验(RIHA)试剂的样品为78.57%。结论兰州生物制品研究所有限责任公司研制的鼠疫菌F1抗体酶联免疫诊断试剂盒和鼠疫菌F1抗原酶联免疫诊断试剂盒性质特异,其敏感性优于IHA试剂盒和GICA试剂条,值得在鼠疫的监测和快速诊断中推广应用。     

Salivary peroxidase,Pm, and Ph protein polymorphisms in Malaysians

Summary Three human saliva genetic markers, namely, salivary peroxidase (SAPX), Pm, and Ph proteins, were investigated in the three major ethnic groups of Malaysia: Malays, Chinese, and Indians.For Pm, the allelic frequencies of Pm ⁺ for Malays, Chinese, and Indians are 0.385±0.030, 0.282±0.026, and 0.289±0.026 respectively. For Ph, the allelic frequencies of Ph ⁺ are 0.082±0.016 for Malays, 0.109±0.017 for Chinese, and 0.062±0.013 for Indians. For SAPX, the allelic frequencies of SAPX ¹ in Malays, Chinese, and Indians are 0.762±0.027, 0.755±0.027, and 0.723±0.026 respectively.     

Chromosomal location of genes for resistance to powdery mildew in common wheat (Triticum aestivum L. em Thell.). 5. Alleles at the Pm1 locus

 The chromosomal location and genetic characterization of powdery mildew resistance genes were determined in the common wheat lines MocZlatka, Weihenstephan Stamm M1N and in a resistant line of Triticum aestivum ssp. spelta var. duhamelianum. Monosomic analyses revealed that one major dominant gene is located on chromosome 7A in each of the lines tested. Allelism tests with Pm1 in the backcross-derived line Axminster/8^*Cc on 7A indicated that the resistance genes are alleles at the Pm1 locus. These alleles are now designated Pm1a in line Axminster/8^*Cc, Pm1b in MocZlatka, Pm1c in Weihenstephan Stamm M1N, and Pm1d in T. spelta var. duhamelianum, respectively. Received: 10 November 1997 / Accepted: 29 January 1998     

Suppressed recombination rate in 6VS/6AL translocation region carrying the Pm21 locus introgressed from Haynaldia villosa into hexaploid wheat

Pm21 is an effective gene for powdery mildew resistance transferred from Haynaldia villosa into common wheat cultivars. No virulence against this gene has been detected so far. A set of 42 powdery mildew isolates collected in Israel and tested in the current study also revealed no virulence against this gene. Pm21 was previously reported to be located on the short arm of 6VS/6AL translocation chromosome. We constructed a high-density genetic map of chromosome 6A, consisting of 28 PCR markers and the Pm21 gene. A comparison with previously published genetic maps of wheat chromosome 6A revealed that the recombination rate in the 6VS/6AL translocation region was poor. We assume that suppressed recombination caused by the alien H. villosa genetic material is the most reasonable explanation for the tight genetic linkage and the inadequacy between the Pm21 genetic map and the Pm21 physical map of 6A. A large number of sequence-tag sites (STS) and simple sequence repeat markers, which co-segregate with or are closely linked to the Pm21 gene, and the conversion of three resistance gene analog markers into new STS markers, provide a reliable and easy-to-use molecular tool for marker-assisted selection of Pm21 in wheat breeding programs. An additional gene, Pm31, previously reported to be derived from Triticum dicoccoides, was mapped into a similar genomic location to Pm21. Screening of the parental lines and the mapping population with Pm21 diagnostic markers clearly confirmed that the donor line of Pm31 is H. villosa and not T. dicoccoides. Therefore, we conclude that Pm21 and Pm31 refer to the same gene, derived from H. villosa, and that the designation of Pm31 as a new Pm gene was erroneous.     

Application of a non-species dependent ELISA for the detection of antibodies in sera of Burkholderia pseudomallei-immunized goats

A modified, non-species dependent ELISA was performed to detect antibodies in sera of Burkholderia pseudomallei-immunized goats using protein G- or protein A-peroxidase conjugates. The rise of antibody titers during the immunization period exhibited corresponding results by modified ELISA comparison to conventional ELISA and the IHA. Regarding the increase of antibody levels from the pre-immunized baseline to the post-immunized status, the antibody titer detected by modified ELISA was higher than IHA but lower than conventional ELISA. Further efforts are needed to improve the modified ELISA for the diagnosis of melioidosis in animals.     

Influenza A Neuraminidase Antibody Assay with Sensitized Erythrocytes

Erythrocytes sensitized with purified neuraminidase (Hong Kong) antigens were used for assay of influenza A neuraminidase antibodies. The neuraminidase indirect hemagglutination test was equal to the neuraminidase hemagglutination-inhibition (enhancement) test and appeared to be better than the neuraminidase inhibition test for detection of fourfold or greater antibody rises in paired sera from influenza patients or vaccinees. It was better than both tests for detection of neuraminidase antibody. The neuraminidase indirect hemagglutination test is simple to perform and has the advantage of direct antigen-antibody assay.