Assessment of Anti-SARS-CoV-2 antibody levels among university students vaccinated with different COVID-19 primary and booster doses - fall 2021, Wisconsin

BACKGROUND

University students commonly received COVID-19 vaccinations before returning to U.S. campuses in the Fall of 2021. Given likely immunologic variation among students based on differences in type of primary series and/or booster dose vaccine received, we conducted serologic investigations in September and December 2021 on a large university campus in Wisconsin to assess anti-SARS-CoV-2 antibody levels.

METHODS

We collected blood samples, demographic information, and COVID-19 illness and vaccination history from a convenience sample of students. Sera were analyzed for both anti-spike (anti-S) and anti-nucleocapsid (anti-N) antibody levels using World Health Organization standardized binding antibody units per milliliter (BAU/mL). Levels were compared across categorical primary COVID-19 vaccine series received and binary COVID-19 mRNA booster status. The association between anti-S levels and time since most recent vaccination dose was estimated by mixed-effects linear regression.

RESULTS

In total, 356 students participated, of whom 219 (61.5%) had received a primary vaccine series of Pfizer-BioNTech or Moderna mRNA vaccines and 85 (23.9%) had received vaccines from Sinovac or Sinopharm. Median anti-S levels were significantly higher for mRNA primary vaccine series recipients (2.90 and 2.86 log [BAU/mL], respectively), compared with those who received Sinopharm or Sinovac vaccines (1.63 and 1.95 log [BAU/mL], respectively). Sinopharm and Sinovac vaccine recipients were associated with a significantly faster anti-S decline over time, compared with mRNA vaccine recipients (P <.001). By December, 48/172 (27.9%) participants reported receiving an mRNA COVID-19 vaccine booster, which reduced the anti-S antibody discrepancies between primary series vaccine types.

CONCLUSIONS

Our work supports the benefit of heterologous boosting against COVID-19. COVID-19 mRNA vaccine booster doses were associated with increases in anti-SARS-CoV-2 antibody levels; following an mRNA booster dose, students with both mRNA and non-mRNA primary series receipt were associated with comparable levels of anti-S IgG.

University-Based Outbreaks of Meningococcal Disease Caused by Serogroup B, United States, 2013-2018

We reviewed university-based outbreaks of meningococcal disease caused by serogroup B and vaccination responses in the United States in the years following serogroup B meningococcal (MenB) vaccine availability. Ten university-based outbreaks occurred in 7 states during 2013–2018, causing a total of 39 cases and 2 deaths. Outbreaks occurred at universities with 3,600–35,000 undergraduates. Outbreak case counts ranged from 2 to 9 cases; outbreak duration ranged from 0 to 376 days. All 10 universities implemented MenB vaccination: 3 primarily used MenB-FHbp and 7 used MenB-4C. Estimated first-dose vaccination coverage ranged from 14% to 98%. In 5 outbreaks, additional cases occurred 6–259 days following MenB vaccination initiation. Although it is difficult to predict outbreak trajectories and evaluate the effects of public health response measures, achieving high MenB vaccination coverage is crucial to help protect at-risk persons during outbreaks of meningococcal disease caused by this serogroup.

Distinct evolutionary patterns of Neisseria meningitidis serogroup B disease outbreaks at two universities in the USA

Neisseria meningitidis serogroup B (MnB) was responsible for two independent meningococcal disease outbreaks at universities in the USA during 2013. The first at University A in New Jersey included nine confirmed cases reported between March 2013 and March 2014. The second outbreak occurred at University B in California, with four confirmed cases during November 2013. The public health response to these outbreaks included the approval and deployment of a serogroup B meningococcal vaccine that was not yet licensed in the USA. This study investigated the use of whole-genome sequencing(WGS) to examine the genetic profile of the disease-causing outbreak isolates at each university. Comparative WGS revealed differences in evolutionary patterns between the two disease outbreaks. The University A outbreak isolates were very closely related, with differences primarily attributed to single nucleotide polymorphisms/insertion-deletion (SNP/indel) events. In contrast, the University B outbreak isolates segregated into two phylogenetic clades, differing in large part due to recombination events covering extensive regions (>30 kb) of the genome including virulence factors. This high-resolution comparison of two meningococcal disease outbreaks further demonstrates the genetic complexity of meningococcal bacteria as related to evolution and disease virulence.

Meningococcal carriage among a university student population - United States, 2015

OBJECTIVES

Several outbreaks of serogroup B meningococcal disease have occurred among university students in recent years. In the setting of high coverage of the quadrivalent meningococcal conjugate vaccine and prior to widespread use of serogroup B meningococcal vaccines among adolescents, we conducted surveys to characterize the prevalence and molecular characteristics of meningococcal carriage among university students.

METHODS

Two cross-sectional oropharyngeal carriage surveys were conducted among undergraduates at a Rhode Island university. Isolates were characterized using slide agglutination, real-time polymerase chain reaction (rt-PCR), and whole genome sequencing. Adjusted prevalence ratios and 95% confidence intervals were calculated using Poisson regression to determine risk factors for carriage.

RESULTS

A total of 1837 oropharyngeal specimens were obtained from 1478 unique participants. Overall carriage prevalence was 12.7-14.6% during the two survey rounds, with 1.8-2.6% for capsular genotype B, 0.9-1.0% for capsular genotypes C, W, or Y, and 9.9-10.8% for nongroupable strains by rt-PCR. Meningococcal carriage was associated with being male, smoking, party or club attendance, recent antibiotic use (inverse correlation), and recent respiratory infections.

CONCLUSIONS

In this university setting, the majority of meningococcal carriage was due to nongroupable strains, followed by serogroup B. Further evaluation is needed to understand the dynamics of serogroup B carriage and disease among university students.

Current Epidemiology of Serogroup W Meningococcal Disease—United States, 2010–2015

Background

Serogroup W (NmW) meningococcal disease is a rare but severe infection. Following an NmW outbreak after the Hajj in 2000, NmW disease, predominantly caused by sequence type (ST)-11 clonal complex (cc), rapidly increased in South Africa, South America, and the UK. We describe NmW meningococcal disease epidemiology in the USA during 2010–2015.

Methods

Data were collected from the National Notifiable Diseases Surveillance System, Active Bacterial Core surveillance, and state health departments. Isolates were serogrouped via slide agglutination and real-time polymerase chain reaction. For cases lacking a serogroup result at CDC, the state result was used. Case-fatality ratios (CFR) were calculated using the proportion of cases with known outcomes as the denominator. cc and ST were determined using multilocus sequence typing (MLST).

Results

From 2010 to 2015, 3,504 meningococcal disease cases were reported to CDC; 2,976 (85%) had a serogroup result, of which 290 (10%) were NmW. Although the number of NmW cases reported annually remained fairly stable (range: 40–57), the total number of reported meningococcal disease cases decreased by 60%, and the proportion of cases due to NmW increased from 6% (42/830) in 2010 to 12% (40/332) in 2015. The majority of NmW cases were reported from five states: Florida (n = 106), California (n = 31), New York (n = 25), Georgia (n = 19), and Oregon (n = 11). Half of people with NmW disease were male, 185 (64%) were white, and 84 (29%) were Hispanic. The median age was 51 years (interquartile range: 26–70). Overall, 20% (52/259) of NmW cases were fatal, compared with CFRs for serogroups B (15%), Y (18%), or C (24%). NmW CFR was highest among adults aged 50–59 years (38%). MLST results were available for 119 (41%) of NmW cases: 76 (64%) were cc11, 40 (34%) were cc22, and 1 each were cc23, cc32, and an unassigned cc. cc appeared to be geographically associated: cc11 was concentrated in Florida and Georgia, while cc22 predominated on the West coast. Within cc11, the majority of isolates (86%) were ST-11, and within cc22 the majority (73%) were ST-22.

Conclusion

A rapid increase in NmW disease has not been observed in the USA. Most NmW cases were reported in a limited number of states, with geographic differences in clonal complex.

Disclosures

All authors: No reported disclosures.

Meningococcal Carriage Evaluation in Response to a Serogroup B Meningococcal Disease Outbreak and Mass Vaccination Campaign at a College-Rhode Island, 2015-2016

Background

Serogroup B meningococcal disease caused 7 US university outbreaks during 2013-2016. Neisseria meningitidis can be transmitted via asymptomatic nasopharyngeal carriage. MenB-FHbp (factor H binding protein), a serogroup B meningococcal (MenB) vaccine, was used to control a college outbreak. We investigated MenB-FHbp impact on meningococcal carriage.

Methods

Four cross-sectional surveys were conducted in conjunction with MenB-FHbp vaccination campaigns. Questionnaires and oropharyngeal swabs were collected from students. Specimens were evaluated using culture, slide agglutination, real-time polymerase chain reaction (rt-PCR), and whole genome sequencing. Adjusted prevalence ratios (aPRs) were calculated using generalized estimating equations.

Results

During each survey, 20%-24% of participants carried any meningococcal bacteria and 4% carried serogroup B by rt-PCR. The outbreak strain (ST-9069) was not detected during the initial survey; 1 student carried ST-9069 in the second and third surveys. No carriage reduction was observed over time or with more MenB-FHbp doses. In total, 615 students participated in multiple surveys: 71% remained noncarriers, 8% cleared carriage, 15% remained carriers, and 7% acquired carriage. Ten students acquired serogroup B carriage: 3 after 1 MenB-FHbp dose, 4 after 2 doses, and 3 after 3 doses. Smoking (aPR, 1.3; 95% confidence interval [CI], 1.1-1.5) and male sex (aPR, 1.3; 95% CI, 1.1-1.5) were associated with increased meningococcal carriage.

Conclusions

Carriage prevalence on campus remained stable, suggesting MenB-FHbp does not rapidly reduce meningococcal carriage or prevent serogroup B carriage acquisition. This reinforces the need for high vaccination coverage to protect vaccinated individuals and chemoprophylaxis for close contacts during outbreaks.

Global Role and Burden of Influenza in Pediatric Respiratory Hospitalizations, 1982-2012: A Systematic Analysis

BACKGROUND

The global burden of pediatric severe respiratory illness is substantial, and influenza viruses contribute to this burden. Systematic surveillance and testing for influenza among hospitalized children has expanded globally over the past decade. However, only a fraction of the data has been used to estimate influenza burden. In this analysis, we use surveillance data to provide an estimate of influenza-associated hospitalizations among children worldwide.

METHODS AND FINDINGS

We aggregated data from a systematic review (n = 108) and surveillance platforms (n = 37) to calculate a pooled estimate of the proportion of samples collected from children hospitalized with respiratory illnesses and positive for influenza by age group (<6 mo, <1 y, <2 y, <5 y, 5-17 y, and <18 y). We applied this proportion to global estimates of acute lower respiratory infection hospitalizations among children aged <1 y and <5 y, to obtain the number and per capita rate of influenza-associated hospitalizations by geographic region and socio-economic status. Influenza was associated with 10% (95% CI 8%-11%) of respiratory hospitalizations in children <18 y worldwide, ranging from 5% (95% CI 3%-7%) among children <6 mo to 16% (95% CI 14%-20%) among children 5-17 y. On average, we estimated that influenza results in approximately 374,000 (95% CI 264,000 to 539,000) hospitalizations in children <1 y-of which 228,000 (95% CI 150,000 to 344,000) occur in children <6 mo-and 870,000 (95% CI 610,000 to 1,237,000) hospitalizations in children <5 y annually. Influenza-associated hospitalization rates were more than three times higher in developing countries than in industrialized countries (150/100,000 children/year versus 48/100,000). However, differences in hospitalization practices between settings are an important limitation in interpreting these findings.

CONCLUSIONS

Influenza is an important contributor to respiratory hospitalizations among young children worldwide. Increasing influenza vaccination coverage among young children and pregnant women could reduce this burden and protect infants <6 mo.

Influenza A(H1N1)pdm09 during air travel

The global spread of the influenza A(H1N1)pdm09 virus (pH1N1) associated with travelers from North America during the onset of the 2009 pandemic demonstrates the central role of international air travel in virus migration. To characterize risk factors for pH1N1 transmission during air travel, we investigated travelers and airline employees from four North American flights carrying ill travelers with confirmed pH1N1 infection. Of 392 passengers and crew identified, information was available for 290 (74%) passengers were interviewed. Overall attack rates for acute respiratory infection and influenza-like illness 1-7 days after travel were 5.2% and 2.4% respectively. Of 43 individuals that provided sera, 4 (9.3%) tested positive for pH1N1 antibodies, including 3 with serologic evidence of asymptomatic infection. Investigation of novel influenza aboard aircraft may be instructive. However, beyond the initial outbreak phase, it may compete with community-based mitigation activities, and interpretation of findings will be difficult in the context of established community transmission.

Transmission of 2009 pandemic influenza A (H1N1) virus among healthcare personnel-Southern California, 2009

OBJECTIVE

In April 2009, 2009 pandemic influenza A (H1N1) (hereafter, pH1N1) virus was identified in California, which caused widespread illness throughout the United States. We evaluated pH1N1 transmission among exposed healthcare personnel (HCP) and assessed the use and effectiveness of personal protective equipment (PPE) early in the outbreak.

DESIGN

Cohort study.

SETTING

Two hospitals and 1 outpatient clinic in Southern California during March 28-April 24, 2009.

PARTICIPANTS

Sixty-three HCP exposed to 6 of the first 8 cases of laboratory-confirmed pH1N1 in the United States.

METHODS

Baseline and follow-up questionnaires were used to collect demographic, epidemiologic, and clinical data. Paired serum samples were obtained to test for pH1N1-specific antibodies by microneutralization and hemagglutination-inhibition assays. Serology results were compared with HCP work setting, role, and self-reported PPE use.

RESULTS

Possible healthcare-associated pH1N1 transmission was identified in 9 (14%) of 63 exposed HCP; 6 (67%) of 9 seropositive HCP had asymptomatic infection. The highest attack rates occurred among outpatient HCP (6/19 [32%]) and among allied health staff (eg, technicians; 8/33 [24%]). Use of mask or N95 respirator was associated with remaining seronegative (P = .047). Adherence to PPE recommendations for preventing transmission of influenza virus and other respiratory pathogens was inadequate, particularly in outpatient settings.

CONCLUSIONS

pH1N1 transmission likely occurred in healthcare settings early in the pandemic associated with inadequate PPE use. Organizational support for a comprehensive approach to infectious hazards, including infection prevention training for inpatient- and outpatient-based HCP, is essential to improve HCP and patient safety.

Repeat revaccination with 23-valent pneumococcal polysaccharide vaccine among adults aged 55-74 years living in Alaska: no evidence of hyporesponsiveness

BACKGROUND

Older adults are at highest risk of invasive pneumococcal disease (IPD) and are recommended to receive vaccination with 23-valent pneumococcal polysaccharide vaccine (PPV23). Antibody concentrations decline following vaccination. We evaluated the immunogenicity and reactogenicity of revaccination and repeat revaccination.

METHODS

Adults aged 55-74 years were vaccinated with a 1st to 4th dose of PPV23. Participants were eligible for revaccination if a minimum of 6 years had passed since their last dose of PPV23. Blood collected on the day of vaccination and 30 days later was analyzed by ELISA for IgG to five serotypes. Functional antibody activity was measured using an opsonophagocytic killing (OPK) assay. Reactions to vaccination were documented.

RESULTS

Subjects were vaccinated with a 1st dose (n=123), 2nd dose (n=121), or 3rd or 4th dose (n=71) of PPV23. The post-vaccination IgG geometric mean concentrations (GMCs) were similar among first-time vaccinees and re-vaccinees for all serotypes with the exception of a lower GMC for serotype 1 in re-vaccinees. The post-vaccination OPK geometric mean titers (GMTs) were similar among first-time vaccinees and re-vaccinees with the exception of a higher GMT for serotype 6B in re-vaccinees. Compared to first-time vaccinees, re-vaccinees reported more joint pain (p=0.004), fatigue (p=0.019), headache (p=0.014), swelling (p=0.006), and moderate limitation in arm movement (p=0.025).

CONCLUSIONS

Repeat revaccination with PPV23, administered 6 or more years after the prior dose, was immunogenic and generally well tolerated.

A real-time polymerase chain reaction for the detection of Streptococcus pneumoniae in blood using a mouse model: a potential new "gold standard"

Better diagnostics for pneumococcal disease are urgently needed. In a murine model, real-time polymerase chain reaction was superior to conventional culture in detecting pneumococcus in blood, particularly in early disease and after antibiotic administration, and could distinguish between commensalism and infection.

Evaluation and improvement of real-time PCR assays targeting lytA, ply, and psaA genes for detection of pneumococcal DNA

The accurate diagnosis of pneumococcal disease has frequently been hampered not only by the difficulties in obtaining isolates of the organism from patient specimens but also by the misidentification of pneumococcus-like viridans group streptococci (P-LVS) as Streptococcus pneumoniae. This is especially critical when the specimen comes from the respiratory tract. In this study, three novel real-time PCR assays designed for the detection of specific sequence regions of the lytA, ply, and psaA genes were developed (lytA-CDC, ply-CDC, and psaA, respectively). These assays showed high sensitivity (<10 copies for lytA-CDC and ply-CDC and an approximately twofold less sensitivity for psaA). Two additional real-time PCR assays for lytA and ply described previously for pneumococcal DNA detection were also evaluated. A panel of isolates consisting of 67 S. pneumoniae isolates (44 different serotypes and 3 nonencapsulated S. pneumoniae isolates from conjunctivitis outbreaks) and 104 nonpneumococcal isolates was used. The 67 S. pneumoniae isolates were reactive in all five assays. The new real-time detection assays targeting the lytA and psaA genes were the most specific for the detection of isolates confirmed to be S. pneumoniae, with lytA-CDC showing the greatest specificity. Both ply PCRs were positive for all isolates of S. pseudopneumoniae, along with 13 other isolates of other P-LVS isolates confirmed to be non-S. pneumoniae by DNA-DNA reassociation. Thus, the use of the ply gene for the detection of pneumococci can lead to false-positive reactions in the presence of P-LVS. The five assays were applied to 15 culture-positive cerebrospinal fluid specimens with 100% sensitivity; and serum and ear fluid specimens were also evaluated. Both the lytA-CDC and psaA assays, particularly the lytA-CDC assay, have improved specificities compared with those of currently available assays and should therefore be considered the assays of choice for the detection of pneumococcal DNA, particularly when upper respiratory P-LVS might be present in the clinical specimen.

Rate of HIV-1 RNA rebound upon stopping antiretroviral therapy

OBJECTIVE

To determine the rate of plasma HIV-1 RNA rebound in patients stopping highly active antiretroviral therapy (HAART) after achieving undetectable viral load.

DESIGN

Sequential plasma HIV RNA levels were measured in six patients during the 21 days following withdrawal from HAART.

METHODS

Plasma samples were obtained from six patients who chose to withdraw from HAART because of lipodystrophy, narcotic overdose, insomnia and/or high blood pressure. Longitudinal plasma viral load was determined in triplicate upon stopping therapy.

RESULTS

All patients had plasma viral loads below 50 HIV RNA copies/ml at the time of stopping therapy and had had levels below 500 copies/ml for a median of 390 days (range 39-542 days). Plasma HIV rebound upon stopping therapy was rapid (median increase 0.2 log/day; range 0.15-0.42 log/day) and initially appeared to follow first-order kinetics. Plasma HIV RNA levels returned to greater than 500 copies/ml within 6 to 15 days (median 10 days) and approached or exceeded pre-therapy levels in all patients within 21 days of stopping therapy. Extrapolating backwards to the time at which individuals stopped therapy suggested that patients had tens of thousands of total body plasma HIV RNA copies despite having 'undetectable' plasma HIV RNA.

CONCLUSIONS

HIV RNA in plasma rebounds within days of stopping antiretroviral therapy. A considerable burden of total body plasma HIV RNA likely remains even during effective HAART therapy.

Differential regulation of matrix metalloproteinases in human cancer cells by exogenous factors

Matrix degradation by cancer cells is an important attribute of malignant behaviour. We have postulated that during invasion and metastasis, matrix metalloproteinase (MMP) production by cancer cells is modulated by microenvironmental factors. To determine this, we screened human cancer cell lines of diverse histogenesis for their secreted MMP profile following exposure to a diversity of soluble and insoluble agents. Enzymatic changes were observed in the presence of phorbol ester (TPA) and hydrogen peroxide (H2O2). More specifically, we observed: (a) increased secretion and/or activation of gelatinases A (MMP-2) and B (MMP-9) after exposure of 8 cell lines to 10(-6) M TPA; (b) increased activation of interstitial collagenase (MMP-1) caseinolysis after stimulation of 3 cancer cell lines with 10(-7) M TPA; and (c) increased activation of MMP-2 after exposure of 2 cell lines to 0.5 mM H3O2. In functional assays, exposure of lung Calu-6 carcinoma cells to 0.5 mM H2O2 and PC-3 cells to TPA, increased their ability to degrade radiolabelled endothelial cell-derived and osteoblast-like-derived basement membranes, respectively. RNA hybridization studies confirmed and further documented these observations. We conclude that modulation of MMP activity in human cancer cells is a common phenomenon regardless of lineage. Modulatory mechanisms such as increased de novo pro-enzyme synthesis and/or release, and enhanced proenzyme activation may be involved. Furthermore, our results provide evidence that extracellular matrix degradation by human cancer cells during invasion and metastasis may be stimulated by soluble matrix-derived factors in a cell type-specific fashion.

Increased expression of activated matrix metalloproteinase-2 by human endothelial cells after sublethal H2O2 exposure

Basement membranes form a boundary between intravascular and extravascular compartments that is remodeled by matrix metalloproteinases (MMP) expressed by endothelial cells. These cells are at risk of exposure to reactive oxygen intermediates generated as a consequence of interactions with drugs, x-radiation, activated neutrophils, or cancer cells. Herein we have investigated the hypothesis that endothelial cells alter their expression of MMP after sublethel exposure to H2O2 and that this leads to degradation of adjacent basement membranes. Cultured human umbilical vein endothelial cells were treated with concentrations of H2O2 ranging from 1.5 to 32 microM or with 2 x 10(-6)M phorbol myristate acetate (PMA). After 24 hours, the cells were placed into serum-free medium for an additional 24 hours. This conditioned medium or cell lysates were studied by matrix degradation assays, gelatin zymography, immunoblots, and Northern analysis. H2O2-treated or PMA-treated cells, or their serum-free conditioned medium, caused a 2-fold increase in degradation of [3H]-proline-labeled endothelial basement membranes or purified type IV collagen compared to untreated cells. Endothelial cells constitutively expressed gelatinases at Mr 96,000 and 72,000, consistent with MMP-9 and inactive MMP-2. H2O2 exposure caused increased expression of these MMP and appearance of Mr 64,000 to 66,000 gelatinases corresponding to activated MMP-2. In cell lysates, H2O2 or PMA treatment led to increased expression of membrane-type MMP-1, an activator of latent MMP-2. The results suggest that oxidants such as H2O2 may stimulate MMP expression and influence the remodeling of vascular basement membranes by endothelial cells.

Magnetic cross-relaxation and chemical exchange between microporous solid and mobile liquid phases

Nuclear magnetic spin-lattice relaxation rates are reported as a function of magnetic field strength, pH, and temperature for water protons in Sephadex gels. The water proton rates report the relaxation profile characteristic of the solid at high pH values. At lower pH values, the relaxation rate is limited by a slow chemical exchange process that makes the relaxation rate independent of magnetic field at low field strengths. In cases where the proton exchange rate does not limit the total relaxation rate, the magnetic field dependence of the relaxation rate is given by a power law of the type R = Av-B, where B is 0.75 except at pH 11 where the data are better represented with B = 0.5. The exchange events important for the water proton relaxation are represented as a two-stage process in which water within the pores of the gel exchanges protons and magnetization with the solid spin system rapidly compared with the rate at which the water within the pores exchanges with the bulk water phase.

Oxygen sensors based on luminescence quenching: interactions of pyrene with the polymer supports

Oxygen quenching of pyrene has been studied in a diverse series of polymers. Most measurements were made using homo- or copolymers containing a poly(dimethylsiloxane) region. Systematic variations in the polymer properties have been made in order to delineate the structural features important for satisfactory use as supports for oxygen sensors. In particular, quenching behavior was examined as a function of the type and amount of copolymer cross-linkers; these were added to produce domains of different polarity and rigidity that would segregate the sensor molecule. A domain model (Xu, W.; et al. Anal. Chem. 1994, 66, 4133-4141) was used to explain the variations in oxygen-quenching properties as a function of additives and cross-linkers. The relative affinity of the different domains for the pyrene and the efficacy of the domains for oxygen quenching controls the overall behavior of the sensing response.

Walker 256 tumor cell degradation of extracellular matrices involves a latent gelatinase activated by reactive oxygen species

The invasion of blood vessel walls is a critical step in cancer metastasis, in which endothelial cells and their vascular basement membranes act as barriers to tumor cell passage. Here we report that Walker 256 carcinosarcoma (W256) cells degrade subendothelial matrices by a process involving both the generation of hydrogen peroxide and the secretion of a matrix metalloproteinase. As an assay of basement membrane degradation, [3H]proline-labeled subendothelial matrices were exposed to W256 cells in the presence or absence of the chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP). The release of [3H]proline, in the presence of 5 x 10(6) W256 cells, was increased from 49 +/- 2.5 to 64 +/- 2.2% by the addition of 10(-6) M fMLP. In the presence of fMLP-activated W256 cells, [3H]proline release was completely inhibited by the addition of 2000 units/ml catalase or by the metalloproteinase inhibitors 1,10-phenanthroline and EDTA at concentrations > or = 10 micrograms/ml. alpha 1-Antitrypsin or alpha 2-macroglobulin were without effect. Cell-free supernatants obtained from activated W256 cells were also able to promote basement membrane degradation. Electrophoresis of the cell-free supernatants from fMLP or PMA-activated W256 cells in gelatin-containing sodium dodecyl sulfate-polyacrylamide gels revealed a major band of gelatinolytic activity at 94 kDa. The 94-kDa band represented the activity of a latent gelatinase since incubation with 1 mM 4-aminophenylmercuric acetate (APMA; a known activator of latent metalloproteinases) resulted in the loss of gelatinolytic activity at 94 kDa and the appearance of five new bands of lower molecular weight (M(r) 86, 79, 74, 70, and 66 kDa). Two of these lower molecular weight bands (M(r) 86 and 66 kDa) were also detected in the absence of APMA, following 10-fold concentration of the cell-free supernatants. When the cell-free supernatants of phorbol myristate acetate-activated W256 cells (concentrated 10-fold) were incubated with increasing concentrations of hydrogen peroxide (35 to 70 mM), the band at 66 kDa demonstrated enhanced gelatinolytic activity. We suggest that W256 cells can secrete a latent metalloproteinase of molecular weight 94 kDa which, when activated by hydrogen peroxide, can degrade subendothelial matrices.

Cantharidin content of two species of Oklahoma blister beetles associated with toxicosis in horses

Cantharidin content of male and female Epicauta occidentalis and E conferta was determined. Aspects of the life cycle of blister beetles, taxonomy, pheromonal and adaptive functions of cantharidin relative to the medico-legal aspects of cantharidin poisoning, prevention and control in horses are discussed.