ABSTRACT
Severe Acute Respiratory Syndrome Coronavirus 2 is the causative agent of Coronavirus Disease 2019 in humans. Among domestic animals, cats are more susceptible to SARS-CoV-2 than dogs. The detection of anti-SARS-CoV-2 antibodies in seemingly healthy cats and/or infected cats which are in close contact with infected humans has been described. The presence of animals that tested positive by serology or molecular techniques could represent a potential transmission pathway of SARS-CoV-2 that can spill over into urban wildlife. This study analyses the seroprevalence variation of SARS-CoV-2 in stray cats from different waves of outbreaks in a geographical area where previous seroepidemiological information of SARS-CoV-2 was available and investigate if SARS-CoV-2-seropositive cats were exposed to other co-infections causing an immunosuppressive status and/or a chronic disease that could lead to a SARS-CoV-2 susceptibility. For this purpose, a total of 254 stray cats from Zaragoza (Spain) were included. This analysis was carried out by the enzyme-linked immunosorbent assay using the receptor binding domain of Spike antigen and confirmed by serum virus neutralization assay. The presence of co-infections including Toxoplasma gondii, Leishmania infantum, Dirofilaria immitis, feline calicivirus, feline herpesvirus type 1, feline leukemia virus and feline immunodeficiency virus, was evaluated using different serological methods. A seropositivity of 1.57% was observed for SARS-CoV-2 including the presence of neutralizing antibodies in three cats. None of the seropositive to SARS-CoV-2 cats were positive to feline coronavirus, however, four SARS-CoV-2-seropositive cats were also seropositive to other pathogens such as L. infantum, D. immitis and FIV (n = 1), L. infantum and D. immitis (n = 1) and L. infantum alone (n = 1).Considering other pathogens, a seroprevalence of 16.54% was detected for L. infantum, 30.31% for D. immitis, 13.78%, for T. gondii, 83.86% for feline calicivirus, 42.52% for feline herpesvirus type 1, 3.15% for FeLV and 7.87% for FIV.Our findings suggest that the epidemiological role of stray cats in SARS-CoV-2 transmission is scarce, and there is no increase in seropositivity during the different waves of COVID-19 outbreaks in this group of animals. Further epidemiological surveillances are necessary to determine the risk that other animals might possess even though stray cats do not seem to play a role in transmission.
ABSTRACT
Severe Acute Respiratory Syndrome Coronavirus 2 is the causative agent of Coronavirus Disease 2019 in humans. To date, little is known about the persistence of antibodies against SARS-CoV-2 in animals under natural conditions, in particular susceptible pets such as cat. This study reports the detection and monitoring of the humoral response against SARS-CoV-2 including the detection of immunoglobulins G specific for receptor binding domain of SARS-CoV-2 spike protein by an enzyme-linked immunosorbent assay and neutralizing antibodies by virus neutralization assay. Results showed that these antibodies last longer than 16 months in two naturally apparently healthy infected cats with the absence of clinicopathological findings during the follow-up. Moreover, re-infection is also possible with an important increase in virus neutralization test titers in both animals with no evident systemic signs found during each physical examination and with values of hematologic and biochemical parameters inside the normal reference intervals. Our results confirm a slow but progressive decrease of the kinetics and immunity of neutralizing antibodies in cats after the infection. Furthermore, similar to humans SARS-CoV-2 reinfection can stimulate an increase of the neutralizing antibodies determined by these two serological techniques in domestic cats.
ABSTRACT
Introduction: Coronavirus disease 2019 (COVID-19) is an infectious zoonotic disease caused by SARS-CoV-2. Monitoring the infection in pets is recommended for human disease surveillance, prevention, and control since the virus can spread from people to animals during close contact. Several diagnostic tests have been adapted from humans to animals, but limited data on the validation process are available. Methods: Herein, the first comparative study of six "in house" and two commercial serological tests developed to monitor SARS-CoV-2 infection in pets was performed with a well-coded panel of sera (61 cat sera and 74 dog sera) with a conservative criterion (viral seroneutralisation and/or RT-qPCR results) as a reference. Four "in house" tests based on either the RBD fragment of the spike protein (RBD-S) or the N-terminal fragment of the nucleoprotein (N) were developed for the first time. The analytical specificity (ASp) of those tests that showed the best diagnostic performance was assessed. The validation included the analysis of a panel of sera obtained pre-pandemic from cats and dogs infected with other coronaviruses to determine the analytical Sp (17 cat sera and 41 dog sera). Results and discussion: ELISAS based on the S protein are recommended in serosurveillance studies for cats (RBD-S SALUVET ELISA, ELISA COVID UNIZAR and INgezim® COVID 19 S VET) and dogs (INgezim® COVID 19 S VET and RBD-S SALUVET ELISA). These tests showed higher diagnostic sensitivity (Se) and DSp in cats (>90%) than in dogs. When sera obtained prior to the pandemic and from animals infected with other coronaviruses were analyzed by RBD-S and N SALUVET ELISAs and INgezim® COVID 19 S VET, a few cross reactors or no cross reactions were detected when dog and cat sera were analyzed by tests based on the S protein, respectively. In contrast, the number of cross reactions increased when the test was based on the N protein. Thus, the use of tests based on the N protein was discarded for serodiagnosis purposes. The results obtained revealed the most accurate serological tests for each species. Further studies should attempt to improve the diagnostic performance of serological tests developed for dogs.
ABSTRACT
The impact of the SARS-CoV-2 pandemic on wildlife is largely unevaluated, and extended surveillance of animal species is needed to reach a consensus on the role of animals in the emergence and maintenance of SARS-CoV-2. This infection has been detected in farmed and domestic animals and wild animals, mainly in captivity. The interactions or shared resources with wildlife could represent a potential transmission pathway for the SARS-CoV-2 spill over to other wild species and could lead to health consequences or the establishment of new reservoirs in susceptible hosts. This study evaluated the presence of SARS-CoV-2 in European mink (Mustela lutreola) and American mink (Neogale vison) in Spain by enzyme-linked immunosorbent assay (ELISA) using the receptor binding domain (RBD) of Spike antigen in serum samples and/or by RT-qPCR assays in oropharyngeal and rectal swabs. From January 2020 to February 2022, a total of 162 animals (127 European mink and 35 American mink) with no evidence of SARS-CoV-2 infection were included in the study. Antibodies against the SARS-CoV-2 were not found in the serum samples analysed (n = 126), nor was the virus amplified by RT-qPCR (n = 160 swabs). Our results suggest that the potential role of wild mink and the European mink bred in captivity and released to the wild as dispersers of SARS-CoV-2 is so far low. However, wildlife surveillance for early detection of human and animal risks should be continued. In this sense, epidemiological monitoring measures, including serology and molecular analysis, are necessary.
ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the zoonotic causative agent of coronavirus disease 2019 (COVID-19) that has caused a pandemic situation with millions of infected humans worldwide. Among domestic animals, there have been limited studies regarding the transmissibility and exposure to the infection in natural conditions. Some animals are exposed and/or susceptible to SARS-CoV-2 infection, such as cats, ferrets and dogs. By contrast, there is no information about the susceptibility of ruminants to SARS-CoV-2. This study tested the antibody response in 90 ovine pre-pandemic serum samples and 336 sheep serum samples from the pandemic period (June 2020 to March 2021). In both cases, the animals were in close contact with a veterinary student community composed of more than 700 members. None of the serum samples analyzed was seroreactive based on an enzyme-linked immunosorbent assay (ELISA) using the receptor-binding domain (RBD) of the spike antigen. In this sense, no statistical difference was observed compared to the pre-pandemic sheep. Our results suggest that it seems unlikely that sheep could play a relevant role in the epidemiology of SARS-CoV-2 infection. This is the first study to report the absence of evidence of sheep exposure to SARS-CoV-2 in natural conditions.
ABSTRACT
Animal infections with SARS-CoV-2 have been reported in different countries and several animal species have been proven to be susceptible to infection with SARS-CoV-2 both naturally and by experimental infection. Moreover, infections under natural conditions in more than 20 mink farms have been reported where humans could have been the source of infection for minks. However, little information is available about the susceptibility of pet animals under natural conditions and currently there is no SARS-CoV-2 epidemiological assessment occurrence in household ferrets. In this study, the presence of SARS-CoV-2 antibodies was evaluated in serum samples obtained from 127 household ferrets (Mustela putorius furo) in the Province of Valencia (Spain). Two ferrets tested positive to SARS-CoV-2 (1.57%) by in-house enzyme-linked immunosorbent assay based on receptor binding domain (RBD) of Spike antigen. Furthermore, anti-RBD SARS-CoV-2 antibodies persisted at detectable levels in a seropositive SARS-CoV-2 domestic ferret beyond 129 days since the first time antibodies were detected. This study reports for the first time the evidence of household pet ferrets exposure to SARS-CoV-2 in Spain to date.
ABSTRACT
Several hundred millions of people have been diagnosed of coronavirus disease 2019 (COVID-19), causing millions of deaths and a high socioeconomic burden. SARS-CoV-2, the causative agent of COVID-19, induces both specific T- and B-cell responses, being antibodies against the virus detected a few days after infection. Passive immunization with hyperimmune plasma from convalescent patients has been proposed as a potentially useful treatment for COVID-19. Using an in-house quantitative ELISA test, we found that plasma from 177 convalescent donors contained IgG antibodies specific to the spike receptor-binding domain (RBD) of SARS-CoV-2, although at very different concentrations which correlated with previous disease severity and gender. Anti-RBD IgG plasma concentrations significantly correlated with the plasma viral neutralizing activity (VN) against SARS-CoV-2 in vitro. Similar results were found using an independent cohort of serum from 168 convalescent health workers. These results validate an in-house RBD IgG ELISA test in a large cohort of COVID-19 convalescent patients and indicate that plasma from all convalescent donors does not contain a high enough amount of anti-SARS-CoV-2-RBD neutralizing IgG to prevent SARS-CoV-2 infection in vitro. The use of quantitative anti-RBD IgG detection systems might help to predict the efficacy of the passive immunization using plasma from patients recovered from SARS-CoV-2.
ABSTRACT
A new coronavirus known as SARS-CoV-2 emerged in Wuhan in 2019 and spread rapidly to the rest of the world causing the pandemic disease named coronavirus disease of 2019 (COVID-19). Little information is known about the impact this virus can cause upon domestic and stray animals. The potential impact of SARS-CoV-2 has become of great interest in cats due to transmission among domestic cats and the severe phenotypes described recently in a domestic cat. In this context, there is a public health warning that needs to be investigated in relation with the epidemiological role of this virus in stray cats. Consequently, in order to know the impact of the possible transmission chain, blood samples were obtained from 114 stray cats in the city of Zaragoza (Spain) and tested for SARS-CoV-2 and other selected pathogens susceptible to immunosuppression including Toxoplasma gondii, Leishmania infantum, feline leukaemia virus (FeLV) and feline immunodeficiency virus (FIV) from January to October 2020. Four cats (3.51%), based on enzyme-linked immunosorbent assay (ELISA) using the receptor binding domain (RBD) of Spike antigen, were seroreactive to SARS-CoV-2. T. gondii, L. infantum, FeLV and FIV seroprevalence was 12.28%, 16.67%, 4.39% and 19.30%, respectively. Among seropositive cats to SARS-CoV-2, three cats were also seropositive to other pathogens including antibodies detected against T. gondii and FIV (n = 1); T. gondii (n = 1); and FIV and L. infantum (n = 1). The subjects giving positive for SARS-CoV-2 were captured in urban areas of the city in different months: January 2020 (2/4), February 2020 (1/4) and July 2020 (1/4). This study revealed, for the first time, the exposure of stray cats to SARS-CoV-2 in Spain and the existence of concomitant infections with other pathogens including T. gondii, L. infantum and FIV, suggesting that immunosuppressed animals might be especially susceptible to SARS-CoV-2 infection.