Maintenance of neutralizing antibodies over ten months in convalescent SARS-CoV-2 afflicted patients

SARS-CoV-2 infection in dogs and cats is associated with contact to COVID-19-positive household members

Several domestic and wild animal species are susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Reported (sero)prevalence in dogs and cats vary largely depending on the target population, test characteristics, geographical location and time period. This research assessed the prevalence of SARS-CoV-2-positive cats and dogs (PCR- and/or antibody positive) in two different populations. Dogs and cats living in a household with at least one confirmed COVID-19-positive person (household (HH) study; 156 dogs and 152 cats) and dogs and cats visiting a veterinary clinic (VC) (VC study; 183 dogs and 140 cats) were sampled and tested for presence of virus (PCR) and antibodies. Potential risk factors were evaluated and follow-up of PCR-positive animals was performed to determine the duration of virus shedding and to detect potential transmission between pets in the same HH. In the HH study, 18.8% (27 dogs, 31 cats) tested SARS-CoV-2 positive (PCR- and/or antibody positive), whereas in the VC study, SARS-CoV-2 prevalence was much lower (4.6%; six dogs, nine cats). SARS-CoV-2 prevalence amongst dogs and cats was significantly higher in the multi-person HHs with two or more COVID-19-positive persons compared with multi-person HHs with only one COVID-19-positive person. In both study populations, no associations could be identified between SARS-CoV-2 status of the animal and health status, age or sex. During follow-up of PCR-positive animals, no transmission to other pets in the HH was observed despite long-lasting virus shedding in cats (up to 35 days). SARS-CoV-2 infection in dogs and cats appeared to be clearly associated with reported COVID-19-positive status of the HH. Our study supports previous findings and suggests a very low risk of pet-to-human transmission within HHs, no severe clinical signs in pets and a negligible pet-to-pet transmission between HHs.

Cumulative SARS-CoV-2 mutations and corresponding changes in immunity in an immunocompromised patient indicate viral evolution within the host

Different scenarios explaining the emergence of novel variants of concern (VOC) of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been reported, including their evolution in scarcely monitored populations, in animals as alternative hosts, or in immunocompromised individuals. Here we report SARS-CoV-2 immune escape mutations over a period of seven months in an immunocompromised patient with prolonged viral shedding. Signs of infection, viral shedding and mutation events are periodically analyzed using RT-PCR and next-generation sequencing based on naso-pharyngeal swabs, with the results complemented by immunological diagnostics to determine humoral and T cell immune responses. Throughout the infection course, 17 non-synonymous intra-host mutations are noted, with 15 (88.2%) having been previously described as prominent immune escape mutations (S:E484K, S:D950N, S:P681H, S:N501Y, S:del(9), N:S235F and S:H655Y) in VOCs. The high frequency of these non-synonymous mutations is consistent with multiple events of convergent evolution. Thus, our results suggest that specific mutations in the SARS-CoV-2 genome may represent positions with a fitness advantage, and may serve as targets in future vaccine and therapeutics development for COVID-19.

Cross-Neutralizing Breadth and Longevity Against SARS-CoV-2 Variants After Infections

Background

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the virus responsible for the Coronavirus Disease 2019 (COVID-19) pandemic. The emergence of variants of concern (VOCs) has become one of the most pressing issues in public health. To control VOCs, it is important to know which COVID-19 convalescent sera have cross-neutralizing activity against VOCs and how long the sera maintain this protective activity.

Methods

Sera of patients infected with SARS-CoV-2 from March 2020 to January 2021 and admitted to Hyogo Prefectural Kakogawa Medical Center were selected. Blood was drawn from patients at 1-3, 3-6, and 6-8 months post onset. Then, a virus neutralization assay against SARS-CoV-2 variants (D614G mutation as conventional strain; B.1.1.7, P.1, and B.1.351 as VOCs) was performed using authentic viruses.

Results

We assessed 97 sera from 42 patients. Sera from 28 patients showed neutralizing activity that was sustained for 3-8 months post onset. The neutralizing antibody titer against D614G significantly decreased in sera of 6-8 months post onset compared to those of 1-3 months post onset. However, the neutralizing antibody titers against the three VOCs were not significantly different among 1-3, 3-6, and 6-8 months post onset.

Discussion

Our results indicate that neutralizing antibodies that recognize the common epitope for several variants may be maintained for a long time, while neutralizing antibodies having specific epitopes for a variant, produced in large quantities immediately after infection, may decrease quite rapidly.

Myocardial Injury Complicated by Systolic Dysfunction in a COVID-19-Positive Dog

Simple Summary

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the coronavirus disease 2019 (COVID-19) pandemic, is continuing to spread worldwide. As with many emerging infectious diseases, COVID-19 is of zoonotic origin, meaning that animals are susceptible to infection, including domestic pets such as dogs. Despite epidemiological surveys conducted in dogs living either in SARS-CoV-2-positive households or in geographic areas affected by COVID-19 steadily increasing, clinical reports aimed at characterising disease manifestation are currently scant in this species. This case report accurately describes the development of myocardial injury complicated by left ventricular systolic dysfunction in a SARS-CoV-2-positive dog. Interestingly, the clinical picture described herein closely resembles the cardiological compromise documented in SARS-CoV-2-positive humans and can therefore contribute to filling the current knowledge gap that exists between human and veterinary medicine concerning COVID-19.

Abstract

A six-year-old Cavalier King Charles spaniel was referred with a two-month history of severe exercise intolerance and syncope. Clinical signs had developed during a local wave of coronavirus disease (COVID-19) two weeks after its family members had manifested symptoms of this viral disease and their positivity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was confirmed. Cardiologic assessment documented myocardial injury complicated by systolic dysfunction. An extensive diagnostic work-up allowed us to rule out common causes of myocardial compromise, both infective and not. Accordingly, serological and molecular tests aimed at diagnosing SARS-CoV-2 infection were subsequently performed, especially in light of the dog’s peculiar history. Results of such tests, interpreted in the light of previous findings and current knowledge from human medicine, supported a presumptive diagnosis of COVID-19-associated myocardial injury, a clinical entity hitherto poorly described in this species.

Determination of neutralising anti-SARS-CoV-2 antibody half-life in COVID-19 convalescent donors

Despite the burgeoning field of coronavirus disease-19 (COVID-19) research, the persistence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralising antibodies remains unclear. This study validated two high-throughput immunological methods for use as surrogate live virus neutralisation assays and employed them to examine the half-life of SARS-CoV-2 neutralising antibodies in convalescent plasma donations made by 42 repeat donors between April and September 2020. SARS-CoV-2 neutralising antibody titres decreased over time but typically remained above the methods' diagnostic cut-offs. Using this longitudinal data, the average half-life of SARS-CoV-2 neutralising antibodies was determined to be 20.4 days. SARS-CoV-2 neutralising antibody titres appear to persist in the majority of donors for several months. Whether these titres confer protection against re-infection requires further study and is of particular relevance as COVID-19 vaccines become widely available.

Immunity after COVID-19 and vaccination: follow-up study over 1 year among medical personnel

BACKGROUND

The long-term course of immunity among individuals with a history of COVID-19, in particular among those who received a booster vaccination, has not been well defined so far.

METHODS

SARS-CoV-2-specific antibody levels were measured by ELISA over 1 year among 136 health care workers infected during the first COVID-19 wave and in a subgroup after booster vaccination approximately 1 year later. Furthermore, spike-protein-reactive memory T cells were quantified approximately 7 months after the infection and after booster vaccination. Thirty healthy individuals without history of COVID-19 who were routinely vaccinated served as controls.

RESULTS

Levels of SARS-CoV-2-specific IgM- and IgA-antibodies showed a rapid decay over time, whereas IgG-antibody levels decreased more slowly. Among individuals with history of COVID-19, booster vaccination induced very high IgG- and to a lesser degree IgA-antibodies. Antibody levels were significantly higher after booster vaccination than after recovery from COVID-19. After vaccination with a two-dose schedule, healthy control subjects developed similar antibody levels as compared to individuals with history of COVID-19 and booster vaccination. SARS-CoV-2-specific memory T cell counts did not correlate with antibody levels. None of the study participants suffered from a reinfection.

CONCLUSIONS

Booster vaccination induces high antibody levels in individuals with a history of COVID-19 that exceeds by far levels observed after recovery. SARS-CoV-2-specific antibody levels of similar magnitude were achieved in healthy, COVID-19-naïve individuals after routine two-dose vaccination.

Long-term persistence of neutralizing SARS-CoV-2 antibodies in pets

We monitored the severe acute respiratory syndrome coronavirus 2 antibody response in seven dogs and two cats by using two multispecies ELISA tests, plaque reduction neutralisation test and virus neutralization. SARS‐CoV‐2 neutralizing antibodies in pets persisted up to 10 months since the first positive testing, thus replicating observations in COVID‐19 human patients.

Maintenance of neutralizing antibodies over ten months in convalescent SARS-CoV-2 afflicted patients

Knowledge of the level and duration of protective immunity against SARS‐CoV‐2 after primary infection is of crucial importance for preventive approaches. Currently, there is a lack of evidence on the persistence of specific antibodies. We investigated the generation and maintenance of neutralizing antibodies of convalescent SARS‐CoV‐2‐afflicted patients over a ten‐month period post‐primary infection using an immunofluorescence assay, a commercial chemiluminescent immunoassay and an in‐house enzyme‐linked neutralization assay. We present the successful application of an improved version of the plaque‐reduction neutralization assay which can be analysed optometrically to simplify data interpretation. Based on the results of the enzyme‐linked neutralization assay, neutralizing antibodies were maintained in 77.4% of convalescent individuals without relevant decay over ten months. Furthermore, a positive correlation between severity of infection and antibody titre was observed. In conclusion, SARS‐CoV‐2‐afflicted individuals have been proven to be able to develop and maintain neutralizing antibodies over a period of ten months after primary infection. Findings suggest long‐lasting presumably protective humoral immune responses after wild‐type infection.