Determination Of Antibody Titers Research Articles

Humoral Immune Response of BNT162b2 and CoronaVac Vaccinations in Hemodialysis Patients: A Multicenter Prospective Cohort.

The CoronaVac vaccine is the most used anti-SARS-CoV-2 vaccine worldwide. Previous data indicate that this vaccine produces a lower immune response than RNA vaccines such as BNT162b2. End-stage renal disease (ESRD) patients have an increased rate of COVID-19 and a reduced immune response to vaccinations. Currently, there is little data on this population’s immune response induced by CoronaVac. Methods: This study involved a prospective cohort of ESRD patients in chronic hemodialysis who received a two-dose immunization scheme of either CoronaVac (Sinovac Biotech) or BNT162b2 vaccines (Pfizer-BioNTech). We measured the plasma levels of anti-SARS-CoV-2 IgG antibodies. We determined antibody titers before immunization, 2 and 4 months after two doses, plus 4 months after a booster dose. Results: We evaluated 208 patients in three hemodialysis centers. The mean age was 62.6 ± 15.6 years, of whom 91 were female (41.75%). Eighty-one patients (38.94%) received the BNT162b2 vaccine and 127 (61.06%) received the CoronaVac vaccine. Patients who received the BNT162b2 vaccine had a higher humoral response compared to those who received the CoronaVac vaccine (4 months after the second dose: BNT162b2: 88.89%, CoronaVac: 51.97%, p < 0.001; 4 months after the booster: BNT162b2: 98.77%, CoronaVac: 86.61%, p < 0.001). Conclusions: Our results suggest that the CoronaVac vaccine induced a lower humoral response than the BNT162b2 vaccine in ESRD patients on hemodialysis.

Age-Dependent Dynamics of Maternally Derived Antibodies (MDAs) and Understanding MDA-Mediated Immune Tolerance in Foot-and-Mouth Disease-Vaccinated Pigs.

Vaccine-induced active immunity in young animals may be compromised via interference caused by maternally derived antibodies (MDAs). Since the level, titer, and half-life of MDAs vary per individual, it is difficult to determine the appropriate timing of foot-and-mouth disease (FMD) vaccination in the field. In order to better understand the age-dependent characteristics of MDA in sows and piglets as well as the phenomenon of reduced vaccine-mediated active immunity due to MDAs, this study sought to determine antibody titers through structural protein (SP) O, A ELISA analyses, and virus-neutralizing (VN) antibody titers as well as their half-lives in the sera of sows and piglets derived from FMD-vaccinated mother. Furthermore, immunoglobulin (Ig) subtypes, such as IgG, IgM, and IgA, in serum were also evaluated. To understand the correlation between the inhibition of vaccine-mediated active immunity by MDA-mediated passive immunity and regulatory T (Treg) cells, Treg-related cytokine levels were explored. Our findings will help to predict the optimal timing of vaccination for overcoming MDAs and inducing a robust vaccine-mediated immune response in young individuals vaccinated against FMD. They also add to our understanding of MDA characteristics and interference, providing insight for the development of innovative strategies and novel FMD vaccine for overcoming such interference.

Seroprevalence of Brucella Infection in a Cohort of HIV-Positive Malawian Pregnant Women Living in Urban Areas.

Background: The seroprevalence of Brucella infection in sub-Saharan regions is high, and no recent data are available for Malawi, a country in which >60% of the population is involved in agropastoral activity. Aim: To evaluated the seroprevalence of Brucella in a cohort of HIV-positive pregnant women, living in an urban setting in Malawi. Methods: Sera of 201 pregnant women were tested for Brucella IgG. The Rose Bengal Plate Test and Serum Agglutination Tube test were used to determine antibody titer. Results: Five out of 201 (2.48%) women show positivity to Brucella, consistent with a past exposition to the infection. All five women delivered healthy infants, but two of them reported previous abortion/stillbirths, with a higher rate than those of the rest of the cohort (40% vs. 21.5%). Conclusions: This is one of the first reports of exposure of pregnant women to Brucella infection in Malawi, providing evidence of Brucella occurrence in an urban setting. Control programs should be introduced to reduce its impact on animal and human health.

Exploratory assessment of serological tests to determine antibody titer against SARS-CoV-2: Appropriateness and limits.

BackgroundSerological tests can be used to detect antibodies in the serum of subject's after SARS‐CoV‐2 infection and vaccination. Currently, variability in antibody titers and the availability of a multiplicity of serological tests have made it necessary to highlight their appropriateness and limitations in various diagnostic settings.MethodsThis study is part of Covidiagnostix, a multicenter project aimed at the assessment of the health technology used in SARS‐CoV‐2 serological tests. Based on data gained from the analysis of over 5000 subjects, a selected number of serum samples, representative of different diagnostic settings, were analyzed first by qualitative immunoassays (IgA, M, and G MILLIPLEX® SARS‐CoV‐2 tests based on Luminex®) to define the immunoglobulins serum composition and subsequently by four serological diagnostic tests (Elecsys Anti‐SARS‐CoV‐2 and Elecsys Anti‐SARS‐CoV‐2 S by Roche, SARS‐CoV‐2 IgG by Siemens Healthcare, and CHORUS SARS‐CoV‐2 “NEUTRALIZING” Ab by DIESSE). The first WHO International Standard for SARS‐CoV‐2 was also analyzed using the same methods.ResultsThis study evaluated the antibody content and titer of the WHO Standard and serum of subjects with/without previous infection and before/after vaccination for SARS‐CoV‐2.ConclusionThe definition of antibodies in the WHO standard and the analysis of serum samples allowed for the identification of the appropriateness of serological tests in each diagnostic setting, increasing the effectiveness of the resulting laboratory data. Furthermore, we found that it would be optimal to produce new international standards against the S1 domain and RBD of the SARS‐CoV‐2 spike protein for a more effective serological monitoring of vaccination.

A Novel Method of CD31-Combined ABO Carbohydrate Antigen Microarray Predicts Acute Antibody-Mediated Rejection in ABO-Incompatible Kidney Transplantation.

Isohemagglutinin assays employing red blood cells (RBCs) are the most common assays used to measure antibody titer in ABO-incompatible kidney transplantation (ABOi KTx). However, ABO antigens expressed on RBCs are not identical to those of kidney and antibody titers do not always correlate with clinical outcome. We previously reported that CD31 was the main protein linked to ABO antigens on kidney endothelial cells (KECs), which was different from those on RBCs. We developed a new method to measure antibody titer using a microarray of recombinant CD31 (rCD31) linked to ABO antigens (CD31-ABO microarray). Mass spectrometry analysis suggested that rCD31 and native CD31 purified from human kidney had similar ABO glycan. To confirm clinical use of CD31-ABO microarray, a total of 252 plasma samples including volunteers, hemodialysis patients, and transplant recipients were examined. In transplant recipients, any initial IgG or IgM antibody intensity >30,000 against the donor blood type in the CD31-ABO microarray showed higher sensitivity, specificity, positive predictive value, and negative predictive value of AABMR, compared to isohemagglutinin assays. Use of a CD31-ABO microarray to determine antibody titer specifically against ABO antigens expressed on KECs will contribute to precisely predicting AABMR or preventing over immunosuppression following ABOi KTx.

Identification of Newcastle Disease case on Kampung Unggul Balitbangtan (KUB) and Sentul Terseleksi (SenSi) chicken in Ungaran Research and Assessment Installation for Agricultural Technology

Newcastle Disease (ND) is a common avian disease that attacks native chickens by causing respiratory problems, thereby leading to a high mortality rate of about 60% per year and economic losses in Indonesia. This study aims to determine the prevalence of ND in Kampung Unggul Balitbangtan (KUB) and Sentul Terseleksi (SenSi) chickens which was conducted from March to June 2021, on their cages at the Ungaran Research and Assessment Installation for Agricultural Technology. The total number of 20 serum KUB and SenSi chicken samples were collected, with 25% KUb A cages, 50% KUB B cages, and 25% SenSi cages. Each chicken’s serum was analyzed for inhibition of hemagglutination (HI) to determine antibody titers against ND. The average antibody titer is expressed as a log2 value. The HI test results indicated that the KUB A cage, KUB B cage, and SenSi cage all contained positive ND antibodies. In the KUB A, KUB B, and the SenSi cages, the average ND antibody titer are 2 log 2, 0.8 log 2, and 2 log 2 respectively. In conclusion, the prevalence of ND antibodies is 100% in KUB and SenSi hens. The ND infection was not described in all chicken cages because the prior vaccine provided a limited level of protection.

Determination of ABO antibody titre and haemolysin test of group O whole blood used for exchanged transfusion in a teaching hospital

Background: Group O blood donor is more readily available and is frequently used as a universal red cell donor and emergency O whole blood (EM O) for exchange transfusion in neonates. Sera from group O donors contains two separable haemolysin antibodies, anti-A and anti-B, and a cross-reacting antibody called anti-A, B (mostly IgG). The presence of haemolysins in the donors may lead to haemolysis in the recipients. Objectives: This study aims to determine the prevalence of anti-A and anti B haemolysins and titer among group O donors that we screened for emergency group O (EM O) whole blood Methodology: A cross sectional study was done to determine the prevalence of anti-A and anti B haemolysin and titer among group O blood donors screened for EM O whole blood for exchange transfusion in neonates at a teaching hospital from January to December 2018. Samples of 350 voluntary group O regular donors were selected for ABO antibodies titration and haemolysin test using the conventional tube technique at room temperature. Donors were screened for titer of 1:50 and 1:100 only. ABO antibody titer of ≥1:100 was considered as a high titer and not suitable for exchange transfusion. Titer of ≤1:50 were labeled as EM O whole blood and will be suitable for exchange transfusion. Results: A total of 350 group O blood donors were screened for the anti A and anti B haemolysin and titer. The majority of blood group O donors were male (n=215, 61%) and were age from 18-30 years old (51%). Malay was the predominant group (83%). About 52.9% of the donors were low titer (≤1:50), and 47.1% were high titer (≥1:100). Low titer was seen predominantly among male donors (61.8%). The prevalence of haemolysins in group O donors was 5.4% (n=19). Anti A and anti B haemolysins were seen in 0.57% and 2.28% of the donors, respectively, while donors having both A and B haemolysins in their sera was 2.57%. Conclusion: Prevalence of anti-A and anti-B haemolysins were low among group O blood donors. However, a significant percentage of group O donors have high titer of anti-A or anti-B. Therefore, despite the labour intensiveness of haemolysis titration technique and the frequent transfusion of group O blood for exchange transfusion, there is the need to routinely screen our donors for haemolysins in order to identify those posing the greatest risk to recipients. Bangladesh Journal of Medical Science Vol. 21 No. 02 April’22 Page : 368-372

Preparation of bovine viral diarrhea disease virus 1 virus-like particles and evaluation of its immunogenicity in a guinea pig model

In order to obtain virus-like particles (VLPs) for prevention of bovine viral diarrhea virus 1 (BVDV-1), the C-Erns-E1-E2 region was cloned into a pFastBacDaul vector for generating the recombinant Bacmid-BVDV-1 in DH10Bac Escherichia coli. The recombinant baculovirus Baculo-BVDV-1 was produced by transfecting the Sf9 cells with Bacmid-BVDV-1. The expressed protein and the assembled VLPs were determined by immunofluorescence, Western blotting and electron microscopy. Guinea pigs were immunized with inactivated VLPs coupled with the Montanide ISA-201 adjuvant. The immunogenicity of VLPs was evaluated by monitoring the humoral immune response with neutralizing antibody titer determination, as well as by analyzing the cell-mediated immune response with lymphocyte proliferation assay. The protective efficacy of VLPs was evaluated by challenging with 106 TCID50 virulent BVDV-1 strain AV69. The results showed that the recombinant Baculo-BVDV-1 efficiently expressed BVDV structural protein and form VLPs in infected Sf9 cells. The immunization of guinea pigs with VLPs resulted in a high titer (1:144) of neutralizing antibody, indicating an activated cellular immunity. Significantly lower viral RNA in the blood of the post-challenged immunized guinea pigs was observed. The successful preparation of BVDV VLPs with insect cell expression system and the observation of the associated immunogenicity may facilitate further development of a VLPs-based vaccine against BVD.

Leptospirosis is an emerging infectious disease of pig-hunting dogs and humans in North Queensland.

BackgroundLeptospirosis is a zoonotic disease with a worldwide distribution, caused by pathogenic serovars in the genus Leptospira. Feral pigs are known carriers of Leptospira species and pig hunting using dogs is a common recreational activity in Queensland, Australia.Methodology and principal findingsThis study aimed to determine the seroprevalence of Leptospira spp. serovars in pig-hunting dogs above the Tropic of Capricorn in Queensland and by establishing the geographic distribution, serovars and incidence of human cases of leptospirosis in Queensland, identify potential overlap between human and canine exposure. We also explored the knowledge and risk-taking behaviours of pig-hunting dog owners towards zoonotic diseases.Ninety-eight pig-hunting dogs deemed healthy by physical examination and owned by 41 people from Queensland had serum submitted for Microscopic Agglutination Testing (MAT) to determine antibody titres against Leptospira serovars, while 40/41 dog owners completed a survey on their knowledge of diseases relating to pig hunting. Human leptospirosis cases (n = 330) notified to Queensland Health between 2015–2018 were analysed.Approximately one quarter (23/87; 26%) of unvaccinated pig-hunting dogs were seropositive to Leptospira spp. Although harder to interpret, 8/11 (73%) vaccinated dogs were seropositive to Leptospira spp. Pig hunters may be more likely to contract leptospirosis compared with the general Queensland population, based on responses from surveyed hunters. The highest concentration of human leptospirosis was in the wet tropics region of Far North Queensland. There was little overlap between the serovars dogs were exposed to and those infecting humans. The dominant serovar identified in unvaccinated dogs was Australis (13/23; 57%), with serovar Arborea (36/330; 10.9%) responsible for the highest number of human leptospirosis cases. Topaz was the second most common serovar in both humans and dogs and was previously unrecorded in Australian dogs. Most hunters surveyed used hand washing as a zoonotic disease risk reduction technique.ConclusionsLeptospirosis is an emerging disease of growing significance. The infection requires a ‘one health’ approach to understand its epidemiology. With shifting climatic patterns influencing human-animal-environment interactions, ongoing monitoring of diseases like leptospirosis is critical to helping prevent infection of individuals and disease outbreaks.

Enzyme-Linked Immunosorbent Assay for Activation of the Classical Complement Pathway by Plasmodium falciparum-Infected Erythrocyte Surface Antigen-Specific Antibodies.

Enzyme-linked immunosorbent assays (ELISA) have a wide range of applications, ranging from specific antibody titer determination to quantification of any biological or non-biological substance with a specific binding partner (usually an antibody). The activity of biological cascades, such as the complement cascade of the innate immune system, can also be assessed by ELISA. We present here an assay optimized for the detection of the activation of the classical complement pathway by polyclonal and monoclonal antibodies (mAbs) specific for Plasmodium falciparum-infected erythrocyte surface antigens.

Diagnostic biomarkers of multiple sclerosis

Multiple sclerosis (MS) is a chronic and inflammatory disease of the central nervous system (CNS) that is common in people between the ages of 20 and 40. Although the exact cause of MS is still unknown, evidences shows that genetic and environmental factors have a role in activating immune cells to attack the myelin sheath of the neurons, and causing them to be damaged. In order to control and reduce the disease prevalence, early identification of at risk people and patients in the early stages of the disease is important. Measurement of interferon gamma (IFN-γ), vitamin D, melatonin, neurofilaments, micro RNA-132 (miR-132), miR-155, determination of antibody titer against Epstein-Barr virus (EBV) and human leukocyte antigen (HLA) typing are appropriate methods to diagnose the disease, and ultimately prevent its recurrence.

Ability to detect antibodies to beak and feather disease virus in blood on filter paper decreases with duration of storage.

BackgroundBeak and feather disease virus (BFDV) is a circovirus that infects captive and wild psittacine birds, and is of conservation concern. The haemagglutination inhibition (HI) assay is used to determine antibody titres against BFDV, and the use of dried blood spots (DBS) on filter paper stored at room temperature has been suggested to be an equally valid technique to the use of frozen serum. However, research on other pathogens has found variable results when investigating the longevity of antibodies stored on DBS at room temperature. Consequently, we aimed to test the temporal stability of antibodies to BFDV in DBS samples stored long-term at room temperature. A further goal was to add to the current knowledge of antibody response to naturally acquired BFDV infection in crimson rosellas (Platycercus elegans).MethodsBlood was collected from wild P. elegans in Victoria, Australia, that had been live-trapped (n = 9) or necropsied (n = 11). BFDV virus load data were obtained from blood stored in ethanol by real-time quantitative PCR (qPCR); antibody titres were obtained by HI assay from either DBS or serum samples, which had been collected concurrently. All HI assays were performed commercially by the Veterinary Diagnostic Laboratory (VDL) in Charles Sturt University, Australia, who were blind to BFDV blood status.ResultsHI titres from DBS stored at room temperature declined significantly over time (~80 weeks). By contrast, frozen serum samples assayed after 80 weeks in storage all had high HI titres, only varying up to one dilution step from the initial HI titres obtained from DBS at 3–6 weeks after sampling. Weak HI titres from DBS samples all came back negative when the test was repeated only nine weeks later. Novel high HI titres were reported in P. elegans, and while most birds with high antibody titres had corresponding negative qPCR results, a single subadult presented with high HI titres and virus load simultaneously.ConclusionDetection of antibodies on filter paper stored at room temperature decreases over time, increasing the chances of false negatives in these samples, and in repeated testing of samples with weak HI titres. Consequently, serum should be the preferred sample type to use for seroepidemiological studies on BFDV in parrots and other bird species. When not possible, it may help to store DBS on filter paper at −20 °C or lower. However, prompt testing of DBS samples (e.g., <6 weeks in storage) is recommended pending further research on antibody temporal stability. We also show that P. elegans, especially adults, can produce high antibody titres against BFDV, which may help them resist infection.

Attenuation of Antibody Titers from 3 to 6 Months after the Second Dose of the BNT162b2 Vaccine Depends on Sex, with Age and Smoking Risk Factors for Lower Antibody Titers at 6 Months.

Objective: We aimed to determine antibody titers at six months and their percentage change from three to six months after the second dose of the BNT162b2 coronavirus disease 2019 (COVID-19) mRNA vaccine (Pfizer/BioNTech) and to explore clinical variables associated with titers in Japan. Methods: We enrolled 365 healthcare workers (250 women, 115 men) whose three-month antibody titers were analyzed in our previous study and whose blood samples were collected 183 ± 15 days after the second dose. Participant characteristics, collected previously, were used. The relationships of these factors with antibody titers at six months and percentage changes in antibody titers from three to six months were analyzed. Results: Median age was 44 years. Median antibody titer at six months was 539 U/mL. Older participants had significantly lower antibody titers (20s, 752 U/mL; 60s–70s, 365 U/mL). In age-adjusted analysis, smoking was the only factor associated with lower antibody titers. Median percentage change in antibody titers from three to six months was −29.4%. The only factor significantly associated with the percentage change in Ab titers was not age or smoking, but sex (women, −31.6%; men, −25.1%). Conclusion: The most important factors associated with lower antibody titers at six months were age and smoking, as at three months, probably reflecting their effect on peak antibody titers. However, the only factor significantly associated with the attenuation in Ab titers from three to six months was sex, which reduced the sex difference seen during the first three months. Antibody titers may be affected by different factors at different time points.

Longitudinal SARS-CoV-2 seroprevalence in Portugal and antibody maintenance 12 months after infection.

During the COVID‐19 pandemic, Portugal has experienced three distinct SARS‐CoV‐2 infection waves. We previously documented the prevalence of SARS‐CoV‐2 immunity, measured by specific antibodies, in September 2020, 6 months after the initial moderate wave. Here, we show the seroprevalence changes 6 months later, up to the second week of March 2021, shortly following the third wave, which was one of the most severe in the world, and 2 months following the start of the vaccination campaign. A longitudinal epidemiological study was conducted, with a stratified quota sample of the Portuguese population. Serological testing was performed, including ELISA determination of antibody class and titers. The proportion of seropositives, which was 2.2% in September 2020, rose sharply to 17.3% (95% CI: 15.8–18.8%) in March 2021. Importantly, circulating IgG and IgA antibody levels were very stable 6 months after the initial determination and up to a year after initial infection, indicating long‐lasting infection immunity against SARS‐CoV‐2. Moreover, vaccinated people had higher IgG levels from 3 weeks post‐vaccination when compared with previously infected people at the same time post‐infection.

O8‐4: Determination of antibody titers of filipino healthcare workers after COVID‐19 vaccination (Sinovac and Astrazenica) ‐ A preliminary report

O8‐4: Determination of antibody titers of filipino healthcare workers after COVID‐19 vaccination (Sinovac and Astrazenica) ‐ A preliminary report

Immunogenicity of SARS-CoV-2 Vaccine in Dialysis.

Patients receiving maintenance dialysis represent a high-risk, immune-compromised population with 15%-25% COVID-19 mortality rate who were unrepresented in clinical trials of mRNA vaccines. All patients receiving maintenance dialysis who received two doses of SARS-CoV-2 mRNA vaccines with antibody test results drawn ≥14 days after the second dose, as documented in the electronic health record through March 18, 2021, were included. Response was on the basis of levels of Ig-G against the receptor binding domain of the S1 subunit of SARS-CoV-2 spike-antigen (seropositive ≥2 U/L) using an FDA-approved semiquantitative chemiluminescent assay (ADVIA Centaur XP/XPT COV2G). Among 186 patients on dialysis from 30 clinics in eight states tested 23±8 days after receiving two vaccine doses, there were 165 (88.7%) responders with 70% at maximum titer. There was no significant difference between BNT162b2/Pfizer (148 out of 168, 88.1%) and mRNA-1273/Moderna (17 out of 18, 94.4%), P=0.42. All 38 patients with COVID-19 history were responders, with 97% at maximum titer. Among patients without COVID-19, 127 out of 148 (85.8%) were responders, comparable between BNT162b2/Pfizer (113 out of 133) and mRNA-1273/Moderna (14 out of 15) vaccines (85.0% versus 93.3%, P=0.38). Most patients receiving maintenance dialysis responded after two doses of BNT162b2/Pfizer or mRNA-1273/Moderna vaccine, suggesting the short-term development of antispike antibody is good, giving hope that most of these patients who are vulnerable, once immunized, will be protected from COVID-19. Longer-term evaluation is needed to determine antibody titer durability and if booster dose(s) are warranted. Further research to evaluate the approach to patients without a serologic response is needed, including benefits of additional dose(s) or administration of alternate options.

Evaluation of oil-based inactivated vaccine against Aeromonas hydrophila administered to Labeo rohita, Cirrhinus mrigala and Ctenopharyngodon idella at different concentrations: Immune response, immersion challenge, growth performance and histopathology

The present study aimed at developing Montanide oil based inactivated vaccine against Aeromonas hydrophila and assessing immunogenic potential of two Indian major carps (Rohu: Labeo rohita and Mori: Cirrhinus mrigala), and a Chinese carp (Grass carp: Ctenopharyngodon idella) commercially cultured in Pakistan. Fishes were randomly distributed in three vaccinated groups with three vaccine concentrations at 108, 109 and 1010 colony forming unit (CFU)/mL and an unvaccinated control group. Fixed dose of 0.1 mL was intraperitoneally injected to each fish on 1st day and a booster dose at 15 days post-vaccination (DPV). Blood samples were collected at 14, 28, 35, 48 and 60 DPV to determine antibody titers in blood serum using complement fixation test (CFT). Growth parameters were also measured on fortnightly basis. The immune response showed highest antibody Geometric Mean Titers (GMT) on 35 DPV in all vaccinated groups which remained significantly higher than control group till 60 DPV. Fishes were challenged at 60 DPV with infectious A. hydrophila with 108 CFU/mL through immersion bath. The relative percentage survival (RPS) was 89% for fishes vaccinated with 109 and 1010 CFU/mL potencies while 78% for 108 CFU/mL potency. Vaccination did not cause adverse effect on growth performance of fishes. Minor degenerations, with non-significant histopathological changes were observed in few vaccinated fishes as compared to control group in which majority of the fishes presented deteriorative changes in tissues histology.

Seroprevalence of Equine Herpesvirus 1 (EHV-1) and Equine Herpesvirus 4 (EHV-4) in the Northern Moroccan Horse Populations

This study reports the first equine herpesvirus-1 (EHV-1) and equine herpesvirus-4 (EHV-4) seroprevalence investigation in horse populations of Morocco in 24 years. It also aims to determine antibody titers in horses vaccinated under field conditions with a monovalent EHV-1 vaccine. Blood samples were collected from 405 horses, including 163 unvaccinated and 242 vaccinated animals. They were tested using a commercial type-specific enzyme-linked immunosorbent assay (ELISA) and a virus neutralization test (VNT). Overall, 12.8% unvaccinated, and 21.8% vaccinated horses were positive for EHV-1. All samples were positive for EHV-4 when tested with the type-specific ELISA. In the vaccinated group, the VNT revealed a mean antibody titer of 1:49 for EHV-1 and 1:45 for EHV-4. The present study demonstrates that EHV-1 and EHV-4 are endemic in the horse populations in the north of Morocco, with prevalence differences between regions. Furthermore, horses vaccinated with a monovalent EHV-1 vaccine had low antibodies titers. This study highlights the necessity to establish and/or support efficient biosecurity strategies based on sound management of horses and characterize further and potentially improve the efficiency of the EHV vaccines and vaccination protocol used in the field.

Blood Culture and Widal Test as Diagnostic Tools for Enteric Fever with Antibiogram in a Tertiary Care Centre at Dhaka in Bangladesh

Background: Enteric fever still exists as one of the major public health issue occurring in our country. Antimicrobials are the mainstays of treatment of typhoid fever. Due to rapidly growing antibiotic resistance, Salmonella spp. is required to be periodically tested for susceptibility patterns. This will also enable planning of rational use of antibiotics.&#x0D; Objective: To observe the diagnostic accuracy of enteric fever by blood culture and Widal test in a tertiary care center, at Savar, Dhaka; Bangladesh. Antimicrobial sensitivity pattern of this study will guide to modify recent changes in the trends of antimicrobial use at the local level.&#x0D; Methodology: Blood samples were collected from 2194 febrile patients with clinically suspected enteric fever cases at a Tertiary Care Outdoor Centre from January 2017 to March 2020. Blood culture was performed to isolate S. typhi and S. paratyphi. Widal tests were done for the determination of antibody titer. An antibody titer of ≥1:80 for anti TO and anti TH were taken as a cut off value to indicate recent infection of typhoid fever. Antibiotic susceptibility testing was carried out using modified disk diffusion (Kirby–Bauer) technique.&#x0D; Results: Out of 111 Salmonella isolates, 74 (5%) were S. typhi and 37 (25%) were S. paratyphi A. Total 697 samples were positive for Widal test. A large number of isolates showed resistance to commonly used antibiotics such as nalidixic acid (94.6%), chloramphenicol (87.3%), amoxicillin (76.6%), cephradine (53.1%), azithromycin (46.8) etc. Resistance to cefixime and cefipime, ceftriaxone tended to increase than past. Imipenem, moxifloxacin and cefuroxime are escalating resistance which is alarming.&#x0D; Conclusion: Blood culture is the most reliable among the diagnostic methods but it needs 5 to 7 days for delivery of final report. This delay leads to late diagnosis as well as provision of irrational usage of antibiotics. It is concluded that widal test would remain relevant as a diagnostic tool for enteric fever, which is more convenient, cheaper and faster than the other molecular tests. Our study revealed the antibiotic susceptibility of Salmonella isolates will be recommended for addressing the drug resistance.

Determination of Chinese hamster ovary (CHO) cell densities and antibody titers from small volumes of cell culture supernatants using multivariate analysis and partial least squares regression of UV-Vis spectra

Antibody titer and viable cell density (VCD) are two important parameters that need to be closely monitored during the process of cell line development and manufacturing of therapeutic antibodies. Typically, determination of each parameter requires 10–100 μL of supernatant sample, which is not suitable for small scale cultivation. In this study, we demonstrated that as low as 2 μL of culture supernatants were sufficient for the analysis using UV-Vis spectrum assisted with partial least squares (PLS) model. The results indicated that the optimal PLS models could be used to predict antibody titer and VCD with the linear relationship between reference values and predicted values at R2 values ranging from 0.8 to > 0.9 in supernatant samples obtained from four different single clones and in polyclones that were cultured in various selection stringencies. Then, the percentage of cell viability and productivity were predicted from a set of samples of polyclones. The results indicated that while all predicted % cell viability were very similar to the actual value at RSEP value of 6.7 and R2 of 0.8908, the predicted productivity from 14 of 18 samples were closed to the reference measurements at RSEP value of 22.4 and R2 of 0.8522. These results indicated that UV-Vis combined with PLS has potential to be used for monitoring antibody titer, VCD, and % cell viability for both online and off-line therapeutic production process.Graphical abstractThe process of multivariate analysis and partial least squares regression of UV-Vis spectrum for the determination of CHO cell densities and antibody titers obtained from small volume of cell culture supernatant samples.