Effects of diet on the bacterial and eukaryotic microbiota across the gastrointestinal tract of healthy rabbits (Oryctolagus cuniculus)

OBJECTIVE

This study aimed to characterize the bacterial and eukaryotic microbiota of the gastrointestinal (GI) tract in domestic rabbits and to evaluate the effect of different diet characteristics, such as pelleting, extrusion, and hay supplementation.

ANIMALS

30 New Zealand White rabbits (15 male and 15 female; 6 to 7 months old) were fed 1 of 6 diets (5 rabbits per diet) for 30 days after an initial acclimation period. At the end of the trial, samples were collected from the stomach, small intestine, cecum, large intestine, and hard feces.

METHODS

The samples were analyzed using 16S rRNA and internal transcribed spacer 1 region-targeted amplicon sequencing.

RESULTS

The bacterial microbiota was distinct between the foregut and hindgut. The most abundant bacterial genera included an unclassified genus in the Bacteroidales order and Alistipes. Candida was the most abundant genus in the eukaryotic dataset. In the bacterial dataset, diet No Hay/Pellet E was shown to have lower diversity (Shannon diversity, P < .05) compared to all diet groups except for No Hay/Pellet M. Few significant differences in alpha-diversity indexes between diet groups were detected in the eukaryotic dataset.

CLINICAL RELEVANCE

Our findings demonstrated that feeding hay had a significant effect on the beta diversity of the bacterial microbiota. Given the prevalence of gastrointestinal disease in the domestic rabbit population, furthering our understanding of what constitutes a healthy rabbit microbiota and the effects of different diets on the microbial community can help veterinarians implement better intervention strategies and allow pet owners to provide the best level of care.

Current data processing methods and reporting standards for untargeted analysis of volatile organic compounds using direct mass spectrometry: a systematic review

INTRODUCTION

Untargeted direct mass spectrometric analysis of volatile organic compounds has many potential applications across fields such as healthcare and food safety. However, robust data processing protocols must be employed to ensure that research is replicable and practical applications can be realised. User-friendly data processing and statistical tools are becoming increasingly available; however, the use of these tools have neither been analysed, nor are they necessarily suited for every data type.

OBJECTIVES

This review aims to analyse data processing and analytic workflows currently in use and examine whether methodological reporting is sufficient to enable replication.

METHODS

Studies identified from Web of Science and Scopus databases were systematically examined against the inclusion criteria. The experimental, data processing, and data analysis workflows were reviewed for the relevant studies.

RESULTS

From 459 studies identified from the databases, a total of 110 met the inclusion criteria. Very few papers provided enough detail to allow all aspects of the methodology to be replicated accurately, with only three meeting previous guidelines for reporting experimental methods. A wide range of data processing methods were used, with only eight papers (7.3%) employing a largely similar workflow where direct comparability was achievable.

CONCLUSIONS

Standardised workflows and reporting systems need to be developed to ensure research in this area is replicable, comparable, and held to a high standard. Thus, allowing the wide-ranging potential applications to be realised.

CLINICAL AND PATHOLOGIC FINDINGS IN IGUANIDS WITH SODIUM URATE CHOLELITHIASIS

Four green iguanas (Iguana iguana) and one blue iguana (Cyclura lewisi) from five facilities were diagnosed with sodium urate cholelithiasis. One case was diagnosed antemortem via ultrasonography, and the iguana underwent a choledochotomy for treatment. The other four cases were identified at necropsy. Pathologic hepatic and biliary changes were present in four of the five cases at necropsy. Histologically, four iguanas had hepatic fibrosis, three had bile duct hyperplasia, and one had cholangiohepatitis and pancreaticocholedochitis. Two iguanas had pathologic renal changes. This is the first report of sodium urate cholelithiasis in reptiles. This case series highlights the potential significant clinical disease caused by sodium urate cholelithiasis and the importance of biliary system evaluation. Further investigation is recommended to explore the pathogenesis of reptilian sodium urate cholelith formation.

Pseudomonas aeruginosa PcrV and Psl, the Molecular Targets of Bispecific Antibody MEDI3902, Are Conserved Among Diverse Global Clinical Isolates

Background

Bispecific antibody MEDI3902, targeting the Pseudomonas aeruginosa type 3 secretion system (PcrV) and Psl exopolysaccharide, is currently in phase 2b development for prevention of nosocomial pneumonia in patients undergoing mechanical ventilation. We surveyed a diverse collection of isolates to study MEDI3902 epitope conservation and protective activity.

Methods

P. aeruginosa clinical isolates (n = 913) were collected from diverse patients and geographic locations during 2003-2014. We conducted whole-genome sequencing; performed PcrV and Psl expression analyses via immunoblotting and enzyme-linked immunosorbent assay, respectively; performed crystallography to determine the MEDI3902 PcrV epitope, using anti-PcrV Fab and PcrV components (resolved at 2.8 Å); and evaluated MEDI3902 protective activity against select isolates in vitro and in vivo.

Results

Intact psl operon and pcrV genes were present in 94% and 99% of isolates, respectively, and 99.9% of isolates contained at least one of the genetic elements. Anti-Psl binding was confirmed in tested isolates harboring a complete Psl operon or lacking nonessential psl genes. We identified 46 PcrV variant sequences, and MEDI3902-PcrV contact residues were preserved. MEDI3902 maintained potent in vivo activity against various strains, including strains expressing only a single target.

Conclusions

Psl and PcrV are highly prevalent in global clinical isolates, suggesting MEDI3902 can mediate broad coverage against P. aeruginosa.

Evaluation of SNAP cPL, Spec cPL, VetScan cPL Rapid Test, and Precision PSL Assays for the Diagnosis of Clinical Pancreatitis in Dogs

BACKGROUND

The sensitivity, specificity, and agreement of 4 diagnostic assays (SNAP canine pancreatic lipase (cPL), specific cPL (Spec cPL), VetScan cPL Rapid Test, and Precision PSL) for pancreatitis in dogs have not been directly compared.

HYPOTHESIS/OBJECTIVES

To determine the level of agreement among each of the 4 assays and a clinical suspicion score, level of agreement among the assays, and sensitivity and specificity of each assay in a clinically relevant patient group.

ANIMALS

Fifty client-owned dogs with clinical signs of gastrointestinal disease.

METHODS

Prospective study. History, physical examination, complete blood count, serum biochemistry, abdominal ultrasound examination, and the 4 diagnostic assays for pancreatitis were performed. Intraclass correlation coefficients (ICC) were used to determine the level of agreement between each assay and a clinical suspicion score determined by a panel of 5 board-certified veterinary internists.

RESULTS

The ICC between the clinical suspicion score and the 4 assays were SNAP cPL, 0.61; Spec cPL, 0.68; VetScan cPL Rapid Test, 0.68; and Precision PSL, 0.60. The sensitivities of the assays ranged from 73.9 to 100.0%, whereas the specificities were SNAP cPL, 71.1-77.8%; Spec cPL, 74.1-81.1%; VetScan cPL Rapid Test, 76.9-83.8%; and Precision PSL, 64.0-74.3%.

CONCLUSIONS AND CLINICAL IMPORTANCE

A good to excellent level of agreement was demonstrated among the 4 assays. The previously unreported sensitivity and specificity of the VetScan cPL Rapid Test were 73.9-83.3% and 76.9-83.8%, respectively. Results of any of the 4 diagnostic assays alone, in the absence of supporting clinical findings, are insufficient to establish a diagnosis of clinical pancreatitis in dogs.

Intestinal Leiomyositis: A Cause of Chronic Intestinal Pseudo-Obstruction in 6 Dogs

BACKGROUND

Intestinal leiomyositis is a suspected autoimmune disorder affecting the muscularis propria layer of the gastrointestinal tract and is a cause of chronic intestinal pseudo-obstruction in humans and animals.

OBJECTIVE

To characterize the clinical presentation, histopathologic features, and outcome of dogs with intestinal leiomyositis in an effort to optimize treatment and prognosis.

ANIMALS

Six client-owned dogs.

METHODS

Retrospective case series. Medical records were reviewed to describe signalment, clinicopathologic and imaging findings, histopathologic diagnoses, treatment, and outcome. All biopsy specimens were reviewed by a board-certified pathologist.

RESULTS

Median age of dogs was 5.4 years (range, 15 months-9 years). Consistent clinical signs included vomiting (6/6), regurgitation (2/6), and small bowel diarrhea (3/6). Median duration of clinical signs before presentation was 13 days (range, 5-150 days). Diagnostic imaging showed marked gastric distension with dilated small intestines in 4/6 dogs. Full-thickness intestinal biopsies were obtained in all dogs by laparotomy. Histopathology of the stomach and intestines disclosed mononuclear inflammation, myofiber degeneration and necrosis, and fibrosis centered within the region of myofiber loss in the intestinal muscularis propria. All dogs received various combinations of immunomodulatory and prokinetic treatment, antimicrobial agents, antiemetics, and IV fluids, but none of the dogs showed a clinically relevant improvement with treatment. Median survival was 19 days after diagnosis (range, 3-270 days).

CONCLUSIONS AND CLINICAL IMPORTANCE

Intestinal leiomyositis is a cause of intestinal pseudo-obstruction and must be diagnosed by full-thickness intestinal biopsy. This disease should be considered in dogs with acute and chronic vomiting, regurgitation, and small bowel diarrhea.

Oral Examination Results in Rescued Ferrets: Clinical Findings

Ferrets have increased in popularity as pets, and a growing number are seen in companion animal practice. Domestic ferrets are commonly used as animal models for research of human oral conditions. The present study evaluated the prevalence of oral pathology in rescued ferrets which – to the authors' knowledge – has not yet been described in the scientific literature. Conscious oral examination was performed on 63 ferrets, of which 49 underwent general anesthesia for further examination. The most common clinical findings included malocclusion of mandibular second incisor teeth (95.2 %); extrusion of canine teeth (93.7 %); and abrasion and attrition of teeth (76.2 %). Tooth fractures were exclusively associated with canine teeth and found in 31.7 % of ferrets. Pulp exposure was confirmed in 60.0 % of fractured teeth. The normal gingival sulcus depth measured < 0.5-mm in 87.8 % of anesthetized ferrets. Clinical evidence of periodontal disease was present in 65.3 % of anesthetized ferrets (gingivitis or probing depths > 0.5-mm), however, advanced periodontal disease (i.e. periodontal pockets > 2-mm or stage 3 furcation exposure) was not found upon clinical examination. There was no evidence of tooth resorption, dental caries, stomatitis, or oral tumors in the examined group of ferrets.

Intraocular osteosarcoma in an Umbrella Cockatoo (Cacatua alba)

An adult, presumed intact female Umbrella Cockatoo (Cacatua alba), presented with acute hemorrhage from an intraocular mass that perforated through the right cornea. Computed tomography scanning revealed a large soft tissue mass in the right orbit, invading and displacing the globe laterally, and destroying the scleral ossicles. There was no evidence of bony changes of the orbit or extension of the mass into the optic nerve or brain. Exenteration and mass removal were performed, and osteosarcoma was diagnosed via histopathology. Radiotherapy was delivered with an orthovoltage unit to a total dose of 68 Gray delivered in 17 fractions over 6 weeks. The bird recovered well from treatment, but died 2 months after the last radiation session with neurological signs. Necropsy was not performed. To our knowledge, this is the first case of an intraocular osteosarcoma reported in a bird, and the first case of attempted treatment of osteosarcoma in a bird by a combination of surgery and radiation therapy.

Risk factors for nuisance barking in dogs

OBJECTIVE

To determine the key variables related to the environment, animal and owner that influence nuisance barking by dogs in a city with a subtropical climate.

DESIGN AND POPULATION

A case-control survey of dog owners in Brisbane, Queensland, was conducted using a questionnaire investigating key variables connected to nuisance barking. Owners of dogs exhibiting nuisance barking were obtained from a list of dogs being treated in a Brisbane behaviour clinic, and those of control dogs were selected from a telephone directory.

RESULTS

Univariate analysis showed that animal, owner and environmental factors all potentially influence the occurrence of nuisance barking. Multivariate analysis identified the following factors, with the relevant odds ratios (OR) as significant: age of the dog (young dog vs old dog, OR 11.2); multiple dogs in the household vs single (OR 5.6); origin of the dog (home bred vs obtained from breeder or friend, OR 4.0); type of dog, (herding vs other types, OR 3.2) and dog with access to the home vs dog without access (OR 2.5).

CONCLUSION

The greatest risk for nuisance barking occurs with a young dog of the herding type that is home bred and with access to the house in a multiple dog household.

The phenol red thread tear test in large Psittaciformes

OBJECTIVE

To develop a standard method for measuring tear production in large Psittaciformes using the phenol red thread (PRT) tear test. To establish mean PRT tear test values in clinically normal pet birds and to assess the reproducibility of the test.

ANIMALS

Two geographically distinct populations of healthy, large Psittaciformes (pilot study and study population). Species groups include: cockatoo (17), macaw (22), Amazon (10), African gray (1), eclectus (1) and pionus (1).

PROCEDURE

The PRT was placed under the upper eyelid and both eyelids were held closed throughout the test. The PRT tear test was repeated after 2 months in the pilot study and after approximately 5 min in the study population.

RESULTS

The mean PRT tear test values for the pilot study were OD=28.2 mm/15 s (+/- 6.3 mm), OS=24.1 mm/15 s (+/- 6.6 mm) and OD=25.4 mm/15 s (+/- 3.3 mm), OS=25.5 mm/15 s (+/- 5.2 mm), for the first and second visits respectively. The mean PRT tear test value for the study population was: OD=19.8 mm/15 s (+/- 4.3 mm), OS=20.1 (+/- 3.9 mm) and OD=20.0 mm/15 s (+/- 4.5 mm), OS=19.1 mm/15 s (+/- 3.3 mm), for the first and second tests respectively. There was poor repeatability between tests.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that the PRT tear test is a practical method for measuring tear production in large Psittaciformes, although adaptations to the established diagnostic method are necessary to overcome some anatomical differences present in birds. Good reproducibility of the PRT tear test could not be demonstrated in a clinically normal population of birds but geographic location appears to significantly influence results.

Future directions in training of veterinarians for small exotic mammal medicine: expectations, potential, opportunities, and mandates

Small exotic mammals have been companions to people for almost as long as dogs and cats have been. The challenge for veterinary medicine today is to decipher the tea leaves and determine whether small mammals are fad or transient pets or whether they will still be popular in 20 years. This article focuses on pet small-mammal medicine, as the concerns of the laboratory animal are better known and may differ profoundly from those of a pet. Dozens of species of small exotic mammals are kept as pets. These pet small-mammal species have historically served human purposes other than companionship: for hunting, for their pelts, or for meat. Now, they are common pets. At present, most veterinary schools lack courses in the medical care of these animals. Veterinary students need at least one required class to introduce them to these pets. Currently, there are no small-mammal-only residency programs. This does not correspond with current needs. The only way to judge current needs is by assessing what employers are looking for. In a recent JAVMA classified section, almost 30% of small-animal practices in suburban/urban areas were hiring veterinarians with knowledge of exotic pets. All veterinarians must recognize that pet exotic small mammals have changed the landscape of small-animal medicine. It is a reality that, today, many small-animal practices see pet exotic small mammals on a daily basis.

Estimated nutrient content of diets commonly fed to pet birds

The owners of 135 pet birds were surveyed by questionnaire to determine their birds' weekly food consumption. The birds were divided into six food groups on the basis of the amounts of seeds, formulated products and human food they consumed. The formulated products and seeds were analysed for their nutrient content by two independent laboratories, the nutrient content of the human foods was obtained from a standard nutrition reference, and each bird's nutrient intake was estimated. The dietary content of individual nutrients was then compared with the estimated maintenance requirements for pet birds. Birds consuming less than approximately 50 per cent of their diets as formulated products had inadequate intakes of vitamins A and D3, and calcium. Diets high in human food were low in protein, energy, vitamins and minerals. Diets high in seed were excessive in fat and deficient in vitamins A and D3, and calcium.

Select new, safer i.v. therapy equipment

Learn how to select i.v. therapy safety equipment that complies with the Needlestick Safety and Prevention Act, which mandates the use of needlestick-prevention devices.

The anti-idiotypic antibody 1F7 selectively inhibits cytotoxic T cells activated in HIV-1 infection

Circulating CD8+ T lymphocyte numbers rise substantially following infection with HIV-1. This expanded CD8+ T cell population includes HIV-specific CTL and CTL that kill activated uninfected CD4+ lymphocytes. Experimental, epidemiological and clinical evidence supports the possibility that expansion of CD8+ CTL contributes to CD4+ T cell depletion and disease progression in human HIV infection. Therefore, modulation of CD8+ T cell numbers or of certain CD8+ CTL activated in HIV-infected individuals may be beneficial. It was found that 1F7, a mAb against an idiotype common to anti-HIV and anti-simian immunodeficiency virus (SIV) antibodies, selectively inhibited both anti-HIV CTL and CTL against uninfected CD4+ T cells. Alloantigen-specific CTL and NK cells from either HIV-infected individuals or controls were unaffected by 1F7. Prolonged incubation of CD8+ T cells from HIV-infected individuals with 1F7 induces apoptosis, which was shown to be reflected functionally in reduced total CTL activity and in especially reduced CTL activity against uninfected CD4+ lymphocytes. The selective reactivity of 1F7 with certain CD8+ CTL could be applied towards the modulation of CD8+ T cell responses involved in AIDS pathogenesis.

Study of the alkylation propensity of cations generated by acidolytic cleavage of protecting groups in Boc chemistry

The alkylation of cysteine residue by different classes of carbonium ions, derived from the cleavage of side chain protective groups in anhydrous HF, was investigated. It was found that side chain protection as beta-2,4-dimethylpent-3-yl ester (Dmp) or 2,4-dimethylpent-3-yloxycarbonyl (Doc) groups resulted in more than seven-fold lower level of alkylated byproducts. This makes Dmp and Doc protection of amino acid side chain during solid phase synthesis particularly valuable in the synthesis of peptides containing cysteine residues or other functional groups prone to alkylation by carbonium ions.

Activation of cAMP synthesis in rat brain cortical membranes by rubidium and cesium ions

Rubidium and cesium chlorides accelerated cAMP synthesis in rat brain cortex membranes, while other alkali metal chlorides had no influence on the rate of this process. The effect was dose-dependent and yielded above 2-fold activation of adenylate cyclase. It has been shown that Rb+ and Cs+ influenced directly the catalytic subunit of the enzyme and did not substitute Mg2+ in formation of the metal-ATP complex in this reaction. The stimulatory effect of Rb+ was additive to the activation of adenylate cyclase by the half-maximal (0.3 microM) as well as by the saturating (10 microM) forskolin concentrations, pointing to the fact that these effectors activate different isoforms of the enzyme in rat brain cortex.

Megaesophagus in nine ferrets

Megaesophagus was diagnosed in 9 adult ferrets. Clinical history of the ferrets included regurgitation, difficulty in swallowing, partial anorexia, and lethargy. Cachexia, dehydration, weakness, and ptyalism were observed on physical examination. Radiography revealed the esophagus of each ferret to be dilated in the thoracic and cervical regions. Of 4 ferrets that had lymphocytopenia, 2 had concurrent leukopenia. Serum biochemical analysis revealed high activity of alanine transaminase (4 ferrets) and aspartate transaminase (3), and hypoglycemia (4). Treatment included administration of fluid, antibiotics, and agents directed against possible primary causes of megaesophagus. Treatments were ineffective, and all of the ferrets died or were euthanatized. All 6 ferrets that were submitted for necropsy had bronchopneumonia, hepatic lipidosis, mild esophagitis, and gastritis. The etiopathogenesis of megaesophagus in the ferrets was not determined.

Ferrets

This article addresses the common ferret diseases encountered by the veterinarian. An introductory section familiarizes the veterinarian with management and preventive health aspects of the pet ferret. Associated clinical techniques are described. Diseases most frequently seen in pet ferrets are discussed.

Monoclonal antibodies to the extracellular domain of HIV-1IIIB gp160 that neutralize infectivity, block binding to CD4, and react with diverse isolates

Ten monoclonal antibodies prepared against a soluble, recombinant form of gp160, derived from the IIIB isolate of HIV-1, were characterized. Four of the antibodies neutralized HIV-1IIIB infectivity in vitro, three blocked the binding of recombinant gp120 to CD4, three were reactive with gp41, and one preferentially reacted with an epitope on gp120 within the gp160 precursor. All three CD4 blocking antibodies bound to distinct epitopes, with one mapping to the C1 domain, one mapping to the C4 domain, and one reactive with a conformation-dependent, discontinuous epitope. Of these, the antibody reactive with the discontinuous epitope exhibited neutralizing activity against homologous and heterologous strains of HIV-1. The binding of these monoclonal antibodies to a panel of seven recombinant gp120s prepared from diverse isolates of HIV-1 was measured, and monoclonal antibodies with broad cross reactivity were identified. The epitopes recognized by 7 of the 10 monoclonal antibodies studied were localized by their reactivity with synthetic peptides and with fragments of gp120 expressed as fusion proteins in a lambda gt-11 gp160 epitope library.

Agreement study between two laboratories of immunofluorescence as a confirmatory test for human immunodeficiency virus type 1 antibody screening

A total of 114 serum specimens from 76 blood donors, 21 patients with acquired immune deficiency syndrome or acquired immune deficiency syndrome-related complex, 7 multiply transfused patients, 3 hemophiliacs, and 7 others were tested for anti-human immunodeficiency virus type 1 (HIV-1) antibody by enzyme immunoassay (EIA) and Western blot (WB) and then blindly tested by immunofluorescence (IF), independently, in two separate laboratories. The IF technique used acetone-fixed HIV-1-infected E cells and uninfected HUT-78 cells mixed at a 1:3 ratio in one spot on a glass slide and uninfected HUT-78 cells (to assess nonspecific fluorescence) alone in a second spot. Of 114 serum specimens, 85 were repeat EIA positive, and 21 of these were WB positive. A total of 129 of 134 of the IF results (included were 20 duplicates) were identical between laboratories, for a Kappa agreement statistic of 0.93. All five IF results discordant between laboratories were EIA repeat positive and WB negative. Included in the study were eight WB-indeterminate sera, of which five blood donor serum specimens and one hemophiliac serum specimen were IF negative and two acquired immune deficiency syndrome serum specimens were IF positive. As a confirmatory test for HIV-1 antibodies, IF provided a faster alternative or supplementary test for confirming EIA results.

Sensitization and tolerance to apomorphine in men: yawning, growth hormone, nausea, and hyperthermia

This study investigated whether the indices of dopaminergic function, yawning and growth hormone release induced by apomorphine, as well as the drug-induced nausea and hyperthermia, show sensitization or tolerance to repeated injections. Five normal volunteers received 12 injections of apomorphine hydrochloride (0.75 mg/70 kg) every 2 weeks. Yawning, as measured by the latency of onset and the time of peak activity, showed sensitization. The growth hormone response showed no change. Feelings of nausea and hyperthermia showed tolerance to repeated injections. These findings suggest that yawning may be a suitable index of dopaminergic function in studies of schizophrenia.

Characterization and epitope mapping of a human monoclonal antibody reactive with the envelope glycoprotein of human immunodeficiency virus

A human monoclonal antibody (IgG2, lambda), 1B8.env, was produced, reactive with the envelope glycoprotein of human immunodeficiency virus (HIV). The antibody specifically stains cells infected with HIV, as assessed by indirect immunofluorescence analysis and reacts with determinants displayed on the surface of infected cells. In Western blot analysis, the antibody reacts with bands of 160 and 41 kD, consistent with the precursor and transmembrane forms of the HIV envelope glycoprotein. The antibody also reacts specifically in immunofluorescence and Western blot analysis with cells infected with the recombinant vaccinia virus VSC-25, which contains the envelope gene of HIV. With the lambda gt11 expression vector, the epitope recognized by 1B8.env was mapped to a region of 11 amino acids in the coding region of gp41. This domain is highly conserved between several otherwise highly variable HIV isolates. In addition, this epitope appears to be recognized by the vast majority of HIV seropositive individuals. Although antibody IB8.env does not neutralize HIV virion infectivity or virally mediated cell fusion, the results presented here demonstrate the feasibility of generating and characterizing human monoclonal antibodies to HIV with these techniques. Additional antibodies produced in this manner will help to further characterize the humoral response to HIV infection, define biologically significant determinants on HIV proteins, and may be useful in clinical applications.

Characterization and epitope mapping of a human monoclonal antibody reactive with the envelope glycoprotein of human immunodeficiency virus

A human monoclonal antibody (IgG2, lambda), 1B8.env, was produced, reactive with the envelope glycoprotein of human immunodeficiency virus (HIV). The antibody specifically stains cells infected with HIV, as assessed by indirect immunofluorescence analysis and reacts with determinants displayed on the surface of infected cells. In Western blot analysis, the antibody reacts with bands of 160 and 41 kD, consistent with the precursor and transmembrane forms of the HIV envelope glycoprotein. The antibody also reacts specifically in immunofluorescence and Western blot analysis with cells infected with the recombinant vaccinia virus VSC-25, which contains the envelope gene of HIV. With the lambda gt11 expression vector, the epitope recognized by 1B8.env was mapped to a region of 11 amino acids in the coding region of gp41. This domain is highly conserved between several otherwise highly variable HIV isolates. In addition, this epitope appears to be recognized by the vast majority of HIV seropositive individuals. Although antibody IB8.env does not neutralize HIV virion infectivity or virally mediated cell fusion, the results presented here demonstrate the feasibility of generating and characterizing human monoclonal antibodies to HIV with these techniques. Additional antibodies produced in this manner will help to further characterize the humoral response to HIV infection, define biologically significant determinants on HIV proteins, and may be useful in clinical applications.

Gene rearrangement in cells with natural killer activity and expression of the beta-chain of the T-cell antigen receptor

The mammalian host defence system can be divided broadly into adaptive and non-adaptive immunity. Adaptive immunity is acquired and is mediated by B and T lymphocytes. Non-adaptive immunity is mediated in part by a small subclass of heterogeneous peripheral blood mononuclear cells. This population, termed null cells, consists of haematopoietic precursors and cells mediating natural killer (NK) activity and antibody-dependent cellular cytotoxicity (ADCC). NK cells are a class of non-adherent, non-phagocytic, rapidly cytotoxic lymphocytes which can efficiently lyse a wide variety of tumour cells, virally infected cells and immature cell types of normal origin. Despite the broad range of targets, only a limited number of specificities are thought to be involved in target-cell recognition. Morphologically, NK cells are large granular lymphocytes, but they have been shown to exhibit cell-surface markers characteristic of both T cells and monocytes, raising doubt over their lineage. The recent cloning of the beta-chain of the T-cell antigen receptor has now allowed us to investigate whether some NK cells are T-cell-related. We have examined rearrangement and expression of the beta-chain of the T-cell receptor in cloned murine NK cell lines and fresh murine NK cell populations, and our results support the hypothesis that a subpopulation of NK cells is related to T cells and provide basis for examining whether some NK activity is mediated by a small number of T-cell receptors.

Regulation of lymphoblast traffic and localization in mucosal tissues, with emphasis on IgA

A fundamentally important factor in the expression of immunity at mucosal sites is the migration of primed lymphocytes to, from, and among mucosal tissues. Despite considerable information in recent years on the selective localization of B lymphoblasts, especially those destined to make IgA antibodies in mucosal tissues, the basis for this remains obscure. Several cell-associated factors such as surface characteristics, histo-compatibility type, and organ derivation of the cells play a significant role for T and B lymphoblast localization. Factors that regulate lymphoblast delivery to tissues, such as blood flow, or control emigration from tissues, such as arachidonic acid metabolites, are discussed. Finally, factors such as the presence or absence of high endothelial venules, isotype-specific T helper cells, sex hormones, antigen, macrophages, and iron all may play a significant role in mucosal lymphoblast localization.