Early high antibody-titre convalescent plasma for hospitalised COVID-19 patients: DAWn-plasma

BackgroundSeveral randomised clinical trials have studied convalescent plasma (CP) for COVID-19 using different protocols, with different SARS-CoV-2 neutralising-antibody-titres, at different time-points and severities of illness.MethodsIn the prospective multicentre DAWN-plasma trial, adult patients hospitalised with COVID-19 were randomised to 4 units of open-label convalescent plasma combined with standard of care (intervention group) or standard of care alone (control group). Plasma from donors with neutralising-antibody-titres (NT50) ≥1/320 was the product of choice for the study.ResultsBetween May 2nd, 2020 and January 26th, 2021, 320 patients were randomised to convalescent plasma and 163 patients to the control group according to a 2:1 allocation scheme. A median volume of 884 mL convalescent plasma (IQR 806–906 mL) was administered, and 80.68% of the units came from donors with neutralising-antibody-titres (NT50) ≥1/320. Median time from onset of symptoms to randomisation was 7 days. The proportion of patients alive and free of mechanical ventilation on Day 15 was not different between both groups (convalescent plasma: 83.74% (n=267) versus control: 84.05% (n=137) – Odds ratio 0.99 (0.59–1.66) – p-value=0.9772). The intervention did not change the natural course of antibody titres. The number of serious or severe adverse events was similar in both study arms, and transfusion-related side effects were reported in 19/320 patients in the intervention group (5.94%).ConclusionsTransfusion of 4 units of convalescent plasma with high neutralising-antibody-titres early in hospitalised COVID-19 patients did not result in a significant improvement of the clinical status, or a reduced mortality.

A persistent epidemic of porcine epidemic diarrhoea virus infection by serological survey of commercial pig farms in northern Vietnam

Background Porcine epidemic diarrhoea (PED) is a highly contagious infectious disease with negative economic impacts on the swine industry. PED outbreaks were reported from 2009 to 2015, but sporadic infection has been observed until now in Vietnam. However, the seroprevalence of PEDV infection has not yet been reported for commercial pig farms in Vietnam. The aim of this study was to assess the seroprevalence of PEDV infection in Vietnamese pig farms to reveal the endemic status of PEDV in northern Vietnam. Results A serological survey of PEDV infection was carried out using indirect ELISA in commercial pig farms in Hai Duong, Hung Yen and Thai Binh provinces in northern Vietnam in 2019. Twenty sera were randomly collected from each of 10 commercial pig farms, from each province; none of the farms had vaccinated for PEDV. Serological evidence of natural PEDV infection, expressed as a high antibody titre, was observed in the pig farms in all 3 provinces. The OD values were significantly higher (p < 0.001) for pig sera from Thai Binh than from Hai Duong and Hung Yen. No significant differences (p > 0.05) were detected for seropositivity to PEDV based on locality, age, pig breed and farm size. Conclusions This study indicates serological evidence of natural PEDV infection with high antibody titre in commercial pig farms. PEDV infection was widespread among the pig population in these 3 provinces and that good management and strict biosecurity are needed at these pig farms.

SARS-Cov-2 Natural Infection in a Symptomatic Cat: Diagnostic, Clinical and Medical Management in a One Health Vision

Despite the reported increase in SARS-CoV-2-infected pets, the description of the clinical features from natural infection and the medical follow up in symptomatic pets is still not sufficiently documented. This study reports the case of an indoor cat that displayed respiratory signs and a gastrointestinal syndrome, following the COVID-19 diagnosis of his owners. Thoracic radiographies were suggestive of bronchial pneumonia, while blood tests were indicative of a mild inflammatory process. Nasal and oropharyngeal swabs tested positive through RT-qPCR assays targeting SARS-CoV-2 genes 14 days after his owners tested positive for the virus. Nasal swabs persisted to be RT-qPCR positive after 31 days. Serology confirmed the presence of antibodies through ELISA, electrochemiluminescence analysis and plaque reduction neutralization test, recording a high antibody titre after 31 days. The cat improved after medical treatment and clinically recovered. This study suggests that exposure to SARS-CoV-2 could lead to a natural infection with bronchial pneumonia in cats along with a possible prolonged persistence of SARS-CoV-2 RNA in the upper airways, albeit at a low level. The cat developed neutralizing antibodies, reaching a high titre after 31 days. Further descriptions of SARS-CoV-2 naturally infected pets, their medical management and diagnostic findings would be useful to enhance knowledge about COVID-19 in susceptible animals.

Antibody Response and Haematological Changes of Nigerian Locally Adapted Turkeys to Sheep Red Blood Cells (SRBC)

Haemagglutination assay and haematological analysis of 143 poults generated as F1 individuals by artificial insemination from randomly selected turkeys of White, Black and Lavender genotypes which are classified by antibody titre was carried out so as to confirm their antibody titre levels in response to sheep red blood cells (SRBC). Results showed that mean values obtained for high and low antibody titres were 7.31 and 2.67 respectively, resulting in the classification of the turkeys into Black high and low, Lavender high and black, and White high and low antibody titres. The genotype’s titre had significant (P <0.05) effect on the packed cell volume (PCV), haemoglobin (Hb), red blood cells (RBC), white blood cells (WBC) and basophil (BAS) of the basal haematological parameters. Genotype’s titre had no significant (P >0.05) effect on the primary response haematological parameters. Meanwhile, the primary response haematological parameters to SRBC antigen varied along the genotypes with the WBC increasing drastically in all the genotypes, signifying the presence of an antigen. The study concluded that the F1 turkey poult population studied diverged along the high and low antibody titre in response to SRBC. Thus, the F1 generation of the high antibody titre genotypes (Black high, White high and Lavender high) can be used as foundation stock for selection of local turkeys for high antibody titre.

Preliminary epitope mapping of Torque teno sus virus 1 and 2 putative capsid protein and serological detection of infection in pigs

The aim of this work is to identify antigenic regions within the ORF1 protein of Torque teno sus virus 1 (TTSuV1) and Torque teno virus sus 2 (TTSuV2) that could be used as antigens to detect virus-specific antibodies following infection in pigs. Protein sequences of TTSuV ORF1 genes were analysed to predict linear antigenic epitopes. Synthesized peptides were analysed for serological reactivity with swine sera. Such an antigenic region was identified at the C terminus of the ORF1 protein of both viruses and showed serological reactivity with 78 % (TTSuV1) and 88 % (TTSuV2) of swine sera. An ELISA with an immunodominant peptide as antigen was used to examine the sera of piglets, aged 4–20 weeks, and adults. Results indicated that TTSuV1- and TTSuV2-specific antibodies were detectable at 4 weeks. Antibody titres increased from week 10 and peaked at week 20. A relatively high antibody titre persisted to adulthood.

SEROLOGICAL EXAMINATION OF PARVOVIRUS INFECTION ON PIG FARMS

Porcine parvovirus (PPV) is one of the causative agents in reproductive disorders in swine that causes great economic losses. The objective of our research was to determine prevalence of this infection on farms with intensive breeding in 5 municipalities in Vojvodina. The research encompassed 19 herds with a total of 344 blood samples screened for the presence of antibodies against PPV (gilts, breeding sows and boars). Serological examination was carried out by haemagglutination inhibition test (HI test). After the analyses of the results, seropositive animals were detected on the farms and there were no PPV-free farms. The determined antibody titre against PPV ranged from 1:64 to 1:16384. Out of 344 examined animals, there were 305 (88.66%) with a high antibody titre (1:1024 to 1:16384). The highest level of antibodies (1:16384) was detected in 145 animals, what is 42.15% of total number. In 24 animals (6.97%) titre antibody was 1:512 and these animals were of low seropositivity. Simultaneously, a comparison of antibodies in blood sera was carried out on 20 gilts (Table 3, farm 2) originating from a farm where the animals were vaccinated against PPV and 20 unvaccinated gilts (Table 4, farm 1) originating from a farm without vaccination against PPV. In unvaccinated animals antibody titre was unequal and ranged from 1:256 to 1:16384, in unvaccinated animals the values were considerably higher and ranged from 1:4096 do 1:16384, and in 17 out of 20 vaccinated pigs (85%) the highest antibody titre was 1:16384.

Antibodies and the Aberdeen typhoid outbreak of 1964: I. The Widal reaction

SUMMARYThe outbreak of typhoid fever in Aberdeen during 1964 (Walker, 1965) presented an opportunity to study the antibody titres of typhoid fever patients and of TAB immunized individuals to obtain further knowledge concerning the behaviour of these titres with the passage of time.This paper gives an abbreviated version of part of a research programme which followed the Aberdeen typhoid outbreak of 1964.The antibody titres of patients were followed up for a period of 2 years after discharge from hospital and the findings have been compared with those in TAB immunized healthy individuals. The following points emerged:(1) The value of the Widal test as an aid to diagnosis was limited;(2) the flagellar antibody titre in patients' sera provided a more reliable aid towards diagnosis than did the somatic antibody titre;(3) the response of immunized and non-immunized patients to the somatic antigens was poor and often delayed well into the period following discharge from hospital;(4) titres of 1/40 and over for Vi agglutinins were present in immunized and non-immunized patients for at least 12 months after discharge without their beingS. typhiexcretors;(5) Vi agglutinin titres as high as 1/40 were present in TAB immunized healthy individuals and also in members of the general public;(6) the presence ofS. typhisepticaemia need not result in a high antibody titre; (7) patients who relapse, may do so without enhancement of previous antibody titres and may relapse even in the presence of earlier appreciable titres.

Sero-Epidemiological Investigation on Peste Des Petits Ruminants in Black Bengal Goats

A natural outbreak suspecting PPR (peste des petits ruminants) was thoroughly investigated and confirmed by monoclonal antibody (mAb)-based enzyme immuno slide assay (EISA). Nasal discharge in early stage of disease course, diarrhoeic faeces and lung as a post-mortem sample was a source of sufficient virus to be detected by this technique. Convalescent polyclonal sera from the recovered animal diagnosed as PPR by EISA revealed high antibody titre by competitive-ELISA. It was found that EISA is suitable, sensitive and specific to confirm PPR infection in both field and laboratory conditions especially in developing country. In the affected houses morbidity and mortality rate was 74.13% and 54.83% respectively and observed high in the age group of 5-8 weeks, but sex difference was not significant. Early rainy season (July 2006) was the period of the present outbreak. Sero-positive animal closer to the outbreak area concluded that virus was circulating in the experimental area of Mymensingh district. Vaccinated sero-nagative animal could withstand the natural disease onset. Purchase of new animal from market and grazing in the same field with infected goats was the source of present outbreak.DOI: http://dx.doi.org/10.3329/bjm.v24i2.1260 Bangladesh J Microbiol, Volume 24, Number 2, December 2007, pp 143-145