Approaching the complexity of Crimean-Congo hemorrhagic fever virus serology: A study in swine

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne zoonotic orthonairovirus of public health concern and widespread geographic distribution. Several animal species are known to seroconvert after infection with CCHFV without showing clinical symptoms. The commercial availability of a multi-species ELISA has led to an increase in recent serosurveillance studies as well as in the range of species reported to be exposed to CCHFV in the field, including wild boar (Sus scrofa). However, development and validation of confirmatory serological tests for swine based on different CCHFV antigens or test principles are hampered by the lack of defined control sera from infected and non-infected animals. For the detection of anti-CCHFV antibodies in swine, we established a swine-specific in-house ELISA using a panel of swine sera from CCHFV-free regions and regions with reported CCHFV circulation. We initially screened more than 700 serum samples from wild boar and domestic pigs and observed a correlation of ≃67% between the commercial and the in-house test. From these sera, we selected a panel of 60 samples that were further analyzed in a newly established indirect immunofluorescence assay (iIFA) and virus neutralization test. ELISA-non-reactive samples tested negative. Interestingly, only a subset of samples reactive in both ELISA and iIFA displayed CCHFV-neutralizing antibodies. The observed partial discrepancy between the tests may be explained by different test sensitivities, antibody cross-reactivities or suggests that the immune response to CCHFV in swine is not necessarily associated with eliciting neutralizing antibodies. Overall, this study highlights that meaningful CCHFV serology in swine, and possibly other species, should involve the performance of multiple tests and careful interpretation of the results.

Epidemiologic Survey of Crimean-Congo Hemorrhagic Fever Virus in Suids, Spain

We conducted a cross-sectional study in wild boar and extensively managed Iberian pig populations in a hotspot area of Crimean-Congo hemorrhagic fever virus (CCHFV) in Spain. We tested for antibodies against CCHFV by using 2 ELISAs in parallel. We assessed the presence of CCHFV RNA by means of reverse transcription quantitative PCR protocol, which detects all genotypes. A total of 113 (21.8%) of 518 suids sampled showed antibodies against CCHFV by ELISA. By species, 106 (39.7%) of 267 wild boars and 7 (2.8%) of 251 Iberian pigs analyzed were seropositive. Of the 231 Iberian pigs and 231 wild boars analyzed, none tested positive for CCHFV RNA. These findings indicate high CCHFV exposure in wild boar populations in endemic areas and confirm the susceptibility of extensively reared pigs to CCHFV, even though they may only play a limited role in the enzootic cycle.

Complete Genome Sequences of Two Pasteurella multocida Isolates from Seabirds

Pasteurella multocida is one of the major causes of mass mortalities in wild birds. Here, we report the complete genome sequences of two P. multocida isolates from wild populations of two endangered seabird species, the Indian yellow-nosed albatrosses ( Thalassarche carteri ) and the northern rockhopper penguins ( Eudyptes moseleyi ).

The proprotein convertase SKI-1/S1P is a critical host factor for Nairobi sheep disease virus infectivity

Nairobi sheep disease virus (NSDV) belongs to the Orthonairovirus genus in the Bunyavirales order and is genetically related to human-pathogenic Crimean-Congo hemorrhagic fever virus (CCHFV). NSDV is a zoonotic pathogen transmitted by ticks and primarily affects naïve small ruminants in which infection leads to severe and often fatal hemorrhagic gastroenteritis. Despite its veterinary importance and the striking similarities in the clinical picture between NSDV-infected ruminants and CCHFV patients, the molecular pathogenesis of NSDV and its interactions with the host cell are largely unknown. Here, we identify the membrane-bound proprotein convertase site-1 protease (S1P), also known as subtilisin/kexin-isozyme-1 (SKI-1), as a host factor affecting NSDV infectivity. Absence of S1P in SRD-12B cells, a clonal CHO-K1 cell variant with a genetic defect in the S1P gene (MBTPS1), results in significantly decreased NSDV infectivity while transient complementation of SKI-1/S1P rescues NSDV infection. SKI-1/S1P is dispensable for virus uptake but critically required for production of infectious virus progeny. Moreover, we provide evidence that SKI-1/S1P is involved in the posttranslational processing of the NSDV glycoprotein precursor. Our results demonstrate the role of SKI-1/S1P in the virus life cycle of NSDV and suggest that this protease is a common host factor for orthonairoviruses and may thus represent a promising broadly-effective, indirect antiviral target.

AB1151 DOES PREDNISONE AFFECT COVID19 VACCINE T CELL RESPONSE? A STUDY OF VACCINE RESPONSE IN PATIENTS WITH IMMUNE SYSTEM DISEASES

Background

A whole blood interferon gamma release assay (IGRA) based on the stimulation of SARS-Cov2-specific memory T cells using purified and full-lenght Spike and Nucleocapsid recombinant proteins was developed, together with anti-Spike antibody detection.

Objectives

To study COVID19 vaccine cellular and humoral responses in patients with immune system diseases (ISD) and healthy controls.

Methods

Non-vaccinated healthy individuals (n=103), SARS-Cov-2 infected individuals (n=9), and 104 samples from individuals having received COVID19 vaccine including 28 non-sars-cov2 infected patients with ISD diseases were included. Preliminary experiments were initiated using different platforms (ELISpot, IGRA, recombinant proteins or peptides) in order to evaluate Spike T cell response in volunteers vaccinated with BNT162b2 showing a S2>S1 poly-epitopic response.

Results

Twenty-eight patients (25 women, 3 men; mean age 59.1(±17,8)) with various ISD were investigated. These patients suffered from lupus (n=14), vasculitis (n=4), myositis (n=2), sarcoidosis (n=2), primary immunodeficiency (n=3), Sjögren’s syndrome (n=2) and pericarditis (n=1). Three patients had received 4 doses, 16 three doses, and 8 two doses of vaccine (Pfizer: n=25; Moderna n=1, Astra-Zeneca n=1). One patient refused the vaccination. The tests were performed 86.7 (±60.5) days after last vaccine dose. Ten patients were on prednisone (mean dose: 11,8 mg, median 7.5 mg, range: 5-40). Among those patients, 6 had only prednisone, 1 was also treated with belimumab, 3 with methotrexate (MTX) and 1 with azathioprine (AZA).

Following COVID19 vaccination, humoral (100% in healthy vs 84.6% in ISD patients) and IGRA-Spike T cell (96% in healthy vs 59.7% in AI patients) responses took place with lower response reported among the ISD disease group (Figure 1). Humoral and cellular COVID19 vaccine responses significantly decrease after 100 days post vaccine.

Figure 1.

SARS-Cov2 humoral and T cell responses in non-vaccinated healthy individuals (n=103), SARS-Cov-2 infected individuals (n=9), and 104 samples from individuals having received COVID19 vaccine including 28 non-Sars-cov2 infected patients with ISD diseases. A- Anti-SARS-Cov2 Spike total IgM/IgG/IgA antibody (Ab) titers (BAU/mL) tested by ELISA. B- Whole blood IFN-γ release assay (IGRA) response to the full-length Spike recombinant protein (IGRA-Spike). C- Whole blood IGRA response to the nucleocapsid recombinant protein (IGRA-Nuc). Positivity cut-off (dot line) p values <0.05 are indicated when significant (ANOVA).

5/5 vaccinated patients on CS alone, 2/5 vaccinated patients on corticosteroids with MTX/AZA/Belimumab and 3/17 other vaccinated patients (all being primary immunodeficiency patients) had no cellular response. Humoral and T cell responses were independent from sex and age.

Conclusion

Altogether, this ongoing study confirms the utility of the IGRA-Spike/-nucleocapsid assay coupled with serology in COVID19 vaccinated individuals and in particular in ISD patients treated with steroids, who may be at risk when the humoral protection decreases.

References

none

Disclosure of Interests

None declared

AB0129 MYOSITIS-SPECIFIC AUTOANTIBODIES IN CLINICAL PRACTICE: IMPROVING THE PERFORMANCES OF THE IMMUNODOT

Background

Idiopathic inflammatory myopathies (IIM) or myositis are a group of rare autoimmune diseases that combine muscle weakness and multi-visceral damage. The discovery of IIM-specific autoantibodies (aAbs) and their associations with clinical phenotypes has improved diagnostic and classification criteria. Faced with the large number of these aAbs, multiplexed techniques have emerged. Among them, the immunodot is simple, rapid, and inexpensive, but has been several times criticized for its lack of specificity.

Objectives

Our objective was to evaluate the current interpretation criteria of the D-Tek immunodot and to propose new interpretation rules based on clinical criteria in order to improve its reliability.

Methods

Were included in this retrospective study patients tested positive result on the semi-quantitative myositis/synthetase immunodots at manufacturer threshold (≥ 5 UA), for at least one of the 15 aAbs: anti-SRP, anti-NXP2, anti-TIF1, anti-SAE (1 and 2), anti-Mi2, anti-MDA5, anti-Jo1, anti-PL7, anti-PL12, anti-EJ, anti-OJ, anti-KS, anti-ZO, anti-HA. Specificity of the immunodots was further evaluated using 60 healthy and anonymous subjects (French blood bank, Toulouse, France). The clinical diagnosis and sub-classification retained by the clinician in charge of the patient was used as a reference for attribution to the myositis/non-myositis group and subgroups. For the myositis group, 7 subgroups were considered: immune-mediated necrotizing myopathy (n=4); dermatomyositis (n=66); anti-synthetase syndrome (n=36); inclusion body myositis (n=1); overlap myositis with another connective tissue disease (n=7); polymyositis (n=8); and unclassified myositis (n=6). For the non-myositis group, patients were subdivided in 4 subgroups: autoimmune or inflammatory diseases (n=72); isolated and diffuse interstitial lung disease (n=26) not associated with other myositis criteria; other non-inflammatory myopathies (n=8) including genetic, metabolic, and toxic myopathies; and other diseases (n=36). The immunodot interpretation thresholds were evaluated both in relation to the manufacturer’s threshold, and by considering the phenotypes and clinical diagnoses using a ROC method (Youden’s index).

Results

Among 270 patients included between 01/07/2016 and 30/06/2020, 128 (47%) were classified as myositis (median age 58 years, 60% women, 52% DM and 28% AS) and 142 (53%) in non-myositis. Among the 15 aAbs analyzed, none were detected in the healthy control group but they were represented in both myositis and non-myositis group. Among them only 2 (anti-Jo1, anti-Mi2) predominate in the myositis group, and 1 (anti-TIF1) in the non-myositis group (Fisher’s test). As quantitative values were found different for 5 aAbs (Mann Whitney test), a clinical threshold was calculated to discriminate myositis from non-myositis groups (ROC curve) allowing to determine an odds ratio (OR). Accordingly, 4/15 (%) aAbs were found associated with myositis: anti-SRP (at 28UA: OR=3.24 95% CI [1.01-10.46], p=0.048), anti-MDA5 (at 15UA: OR=4.36; 95% CI [1.19-15.99], p=0.048), anti-Mi2 (at 5UA: OR =3.24; 95% CI [1.01-10.46], p=0.026), anti-Jo1 (at 5UA: OR= 12.20; 95% CI [2.78-53.52], p<0.0001). All positive predictive values were improved by using a clinical threshold although some of did not reach significance due to their infrequency.

Conclusion

In this retrospective work, despite missing data, the clinical phenotypes of myositis patients and their distribution according to aAbs were comparable to those in the literature. Our study confirms the lack of specificity of D-tek immunodots for IIM-specific aAbs and allows establishing new thresholds improving their performance. Our results should encourage medical biologists to establish local rules of interpretation and reinforce the interest of the discussion between Clinicians and Biologists around the interpretation of these immunodots.

Figure 1.

A: Odd Ratio (OR) evaluated with the manufacturer threshold ≥ 5 and B: OR using Youden’s index (clinical threshold).

Disclosure of Interests

None declared

Causal risk and protective factors in rheumatoid arthritis: A genetic update

The characterization of risk and protective factors in complex diseases such as rheumatoid arthritis (RA) has evolved from epidemiological studies, which test association, to the use of Mendelian randomization approaches, which test direct relationships. Indeed, direct associations with the mucosal origin of RA are retrieved with periodontal disease (Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans predominantly), interstitial lung involvement, tobacco smoking and air pollutants. Next, factors directly associated with an acquired immune response include genetic factors (HLA DRB1, PTPN22), capacity to produce anti-modified protein antibodies (AMPA), and relatives with a history of autoimmune diseases. Finally, factors can be also classified according to their direct capacity to interfere with the IL-6/CRP/sIL-IL6R proinflammatory pathway as risk factor (body fat, cardiometabolic factors, type 2 diabetes, depressive syndrome) or either as protective factors by controlling of sIL-6R levels (higher education level, and intelligence). Although some co-founders have been characterized (e.g. vitamin D, physical activity, cancer) the direct association with sex-discrepancy, pregnancy, and infections among other factors remains to be better explored.

The dive performance of immature king penguins following their annual molt suggests physiological constraints

Like all birds, penguins undergo periodic molt, during which they replace old feathers. However, unlike other birds, penguins replace their entire plumage within a short period while fasting ashore. During molt, king penguins (Aptenodytes patagonicus) lose half of their initial body mass, most importantly their insulating subcutaneous fat and half of their pectoral muscle mass. The latter might challenge their capacity to generate and sustain a sufficient mechanical power output to swim to distant food sources and propel themselves to great depth for successful prey capture. To investigate the effects of the annual molt fast on their dive/foraging performance, we studied various dive/foraging parameters and peripheral temperature patterns in immature king penguins across two molt cycles, after birds had spent their first and second year at sea, using implanted data-loggers. We found that the dive/foraging performance of immature king penguins was significantly reduced during post-molt foraging trips. Dive and bottom duration for a given depth were shorter during post-molt and post-dive surface interval duration was longer, reducing overall dive efficiency and underwater foraging time. We attribute this decline to the severe physiological changes that birds undergo during their annual molt. Peripheral temperature patterns differed greatly between pre- and post-molt trips, indicating the loss of the insulating subcutaneous fat layer during molt. Peripheral perfusion, as inferred from peripheral temperature, was restricted to short periods at night during pre-molt but occurred throughout extended periods during post-molt, reflecting the need to rapidly deposit an insulating fat layer during the latter period.

Thermal strategies of king penguins during prolonged fasting in water

Most animals experience periods of unfavourable conditions, challenging their daily energy balance. During breeding, king penguins fast voluntarily for up to 1.5 months in the colony, after which they replenish their energy stores at sea. However, at sea, birds might encounter periods of low foraging profitability, forcing them to draw from previously stored energy (e.g. subcutaneous fat). Accessing peripheral fat stores requires perfusion, increasing heat loss and thermoregulatory costs. Hence, how these birds balance the conflicting demands of nutritional needs and thermoregulation is unclear. We investigated the physiological responses of king penguins to fasting in cold water by: (1) monitoring tissue temperatures, as a proxy of tissue perfusion, at four distinct sites (deep and peripheral); and (2) recording their oxygen consumption rate while birds floated inside a water tank. Despite frequent oscillations, temperatures of all tissues often reached near-normothermic levels, indicating that birds maintained perfusion to peripheral tissues throughout their fasting period in water. The oxygen consumption rate of birds increased with fasting duration in water, while it was also higher when the flank tissue was warmer, indicating greater perfusion. Hence, fasting king penguins in water maintained peripheral perfusion, despite the associated greater heat loss and, therefore, thermoregulatory costs, probably to access subcutaneous fat stores. Hence, the observed normothermia in peripheral tissues of king penguins at sea, upon completion of a foraging bout, is likely explained by their nutritional needs: depositing free fatty acids (FFA) in subcutaneous tissues after profitable foraging or mobilizing FFA to fuel metabolism when foraging success was insufficient.

Apparent changes in body insulation of juvenile king penguins suggest an energetic challenge during their early life at sea

Little is known about the early life at sea of marine top predators, like deep-diving king penguins (Aptenodytes patagonicus), although this dispersal phase is probably a critical phase in their life. Apart from finding favourable foraging sites, they have to develop effective prey search patterns as well as physiological capacities that enable them to capture sufficient prey to meet their energetic needs. To investigate the ontogeny of their thermoregulatory responses at sea, we implanted 30 juvenile king penguins and 8 adult breeders with a small data logger that recorded pressure and subcutaneous temperature continuously for up to 2.5 years. We found important changes in the development of peripheral temperature patterns of foraging juvenile king penguins throughout their first year at sea. Peripheral temperature during foraging bouts fell to increasingly lower levels during the first 6 months at sea, after which it stabilized. Most importantly, these changes re-occurred during their second year at sea, after birds had fasted for ∼4 weeks on land during their second moult. Furthermore, similar peripheral temperature patterns were also present in adult birds during foraging trips throughout their breeding cycle. We suggest that rather than being a simple consequence of concurrent changes in dive effort or an indication of a physiological maturation process, these seasonal temperature changes mainly reflect differences in thermal insulation. Heat loss estimates for juveniles at sea were initially high but declined to approximately half after ∼6 months at sea, suggesting that juvenile king penguins face a strong energetic challenge during their early oceanic existence.

Precise monitoring of porpoising behaviour of Adelie penguins determined using acceleration data loggers

A new method using acceleration data loggers enabled us to measure the porpoising behaviour of Adelie penguins (Pygoscelis adeliae), defined as a continuous rapid swimming with rhythmic serial leaps. Previous hydrodynamic models suggested that leaping would be energetically cheaper when an animal swims continuously at depths of less than three maximum body diameters below the water surface. In the present study, free-ranging Adelie penguins leapt at a mean speed of 2.8 m s(−)(1) above the predicted threshold speed (0.18-1. 88 m s(−)(1)). Wild penguins reduced drag by swimming deeper (0.91 m) and did not swim continuously within the high-drag layer while submerged. This indicates that previous calculations may be incomplete. Moreover, leaps represented an average of only 3.8 % of the total distance travelled during the porpoising cycle, which would make energy savings marginal. Among the six penguins used in our study, two did not porpoise and three porpoised for less than 7 min, also indicating that this behaviour was not important during travel to and from foraging sites, as has been previously suggested. Birds mainly porpoised at the start and end of a trip. One explanation of porpoising might be an escape behaviour from predators.

Reliability of stomach temperature changes in determining feeding characteristics of seabirds

We examined the accuracy of stomach temperature archival units (STAUs), which are typically used to determine feeding activity in marine endotherms, with regard to determination of the time of prey ingestion as well as the number of prey items ingested and their masses. Units were deployed in nine species of free-living seabirds, where feeding conditions were uncontrolled, eight species of captive seabirds, where feeding conditions could be partially controlled, and in laboratory stomach simulations, where variables could be strictly controlled. The quality of data obtained on the timing of feeding, the mass ingested and the number of prey items ingested was subject to two main sources of error (i) those induced by changes in animal activity and (ii) those resulting from the physical form of the STAUs themselves. Animal activity factors considered important included the following: variability in (a) body temperature, (b) stomach blood perfusion, (c) consistency of stomach contents and (d) stomach churning and changes in body orientation. The physical form (size and buoyancy) of the STAU affected the location of the unit within the stomach, and thus the likelihood that ingested prey comes into contact with the sensor. The timing of prey ingestion can generally be determined accurately; however, considerable errors in mass estimates can occur if data acquired using STAUs are not critically assessed. An understanding of these sources of errors will allow researchers to construct STAUs appropriate to the species being studied and to analyze data critically so that errors are reduced.

[Comparative study of cefixime versus amoxicillin-clavulanic acid combination in the oral treatment of urinary tract infections in children]

BACKGROUND

Acute febrile infections suggestive of pyelonephritis require treatment by broad-spectrum antibiotics capable of reaching significant tissue levels. This study compares efficacy and safety of cefixime with amoxycillin + clavulanic acid in urinary tract infections.

POPULATION AND METHODS

Fifty seven children aged 5 months to 14 years treated for urinary tract infection in ten pediatric centres for a period of 10 months had been randomly included in the study. Thirty (22 girls and eight boys) were given cefixime and 27 (24 girls and three boys) amoxycillin-clavulanate. Efficacy was evaluated in only 36 patients whose bacteria were susceptible to both antibiotics (26 pyelonephritis and ten cystitis).

RESULTS

Sixteen patients out of the 19 given cefixime recovered vs. 14 out of the 17 given amoxycillin-clavulanate with no significant difference between both groups. Bacteria were more often susceptible to cefixime (100% of cases) than to amoxycillin-clavulanate (69%) (p < or = 0.0001). Safety was good and comparable in both groups.

CONCLUSION

Cefixime given per os seems effective and safe in treating urinary tract infections. These results have to be confirmed by further studies.