To accurately diagnose COVID-19 infection and its time-dependent progression, the rapid, sensitive, and noninvasive determination of immunoglobulins A specific to SARS-CoV-2 (IgA) in saliva and serum is needed to complement tests that detect immunoglobulins G and M. We have developed a dual optical/chemiluminescence format of a lateral flow immunoassay (LFIA) immunosensor for IgA in serum and saliva. A recombinant nucleocapsid antigen specifically captures SARS-CoV-2 antibodies in patient specimens. A labelled anti-human IgA reveals the bound IgA fraction. A dual colorimetric and chemiluminescence detection enables the affordable and ultrasensitive determination of IgA to SARS-CoV-2. Specifically, a simple smartphone-camera-based device measures the colour signal provided by nanogold-labelled anti-human IgA. For the ultrasensitive chemiluminescence transduction, we used a contact imaging portable device based on cooled CCD, and measured the light signal resulting from the reaction of the HRP-labelled anti-human IgA with a H 2 O 2 /luminol/enhancers substrate. A total of 25 serum and 9 saliva samples from infected and/or recovered individuals were analysed by the colorimetric LFIA, which was sensitive and reproducible enough for the semi-quantification of IgA in subjects with a strong serological response and in the early stage of COVID-19 infection. Switching to CL detection, the same immunosensor exhibited higher detection capability, revealing the presence of salivary IgA in infected individuals. For the patients included in the study ( n = 4), the level of salivary IgA correlated with the time elapsed from diagnosis and with the severity of the disease. This IgA-LFIA immunosensor could be useful for noninvasively monitoring early immune responses to COVID-19 and for investigating the diagnostic/prognostic utility of salivary IgA in the context of large-scale screening to assess the efficacy of SARS-CoV-2 vaccines.

A fter emerging in Wuhan, China, in December 2019, coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), rapidly became a serious threat to human health worldwide (1-3). Italy has experienced one of the highest rates of human deaths in the world (4).Questions concerning the role of companion animals in the COVID-19 pandemic arose after a dog in Hong Kong reportedly tested positive for SARS-CoV-2 (5). In addition, the World Organisation for Animal Health defi ned COVID-19 as an emerging disease in animals and began promoting surveys on the prevalence of SARS-CoV-2 infections among animals (6). In this context, serologic tests are essential for rapid and accurate screening of animal populations.Few studies have been conducted to clarify the effects domestic animals have in sustaining the SARS-CoV-2 transmission cycle (5,7-9; Q. Zhang et al., unpub. data,

A rapid test for detecting total immunoglobulins directed towards the nucleocapsid protein (N) of severe acute syndrome coronavirus 2 (SARS CoV-2) was developed, based on a multi-target lateral flow immunoassay comprising two test lines. Both test lines bound to several classes of immunoglobulins (G, M, and A). Specific anti-SARS immunoglobulins were revealed by a colorimetric probe formed by N and gold nanoparticles. Targeting the total antibodies response to infection enabled achieving 100% diagnostic specificity (95.75-100, C.I. 95%, n=85 healthy and with other infections individuals) and 94.6% sensitivity (84.9-98.9, C.I. 95%, n= 62 SARS CoV-2 infected subjects) as early as 7 days post confirmation of positivity. Agreeing results with a reference serological ELISA were achieved, except for the earlier detection capability of the rapid test. Follow up of the three seroconverting patients endorsed the hypothesis of the random rise of the different immunoglobulins and strengthened the ‘total antibodies’ approach for the trustworthy detection of serological response to SARS CoV-2 infection.

Funding informationFondazione CARIPLO -Misura a sostegno dello sviluppo di collaborazioni per l'identificazione di terapie e sistemi di diagnostica, protezione e analisi per contrastare l'emergenza Coronavirus e altre emergenze virali del future;

African swine fever (ASF) is a highly contagious and lethal viral disease of pigs and wild boars, which is enzootic in many African countries and on the Italian island of Sardinia, where it has been present since 1978. Previous genetic analyses of Sardinian ASF virus (ASFV) isolates have revealed that they all belong to p72 genotype I, with only minor sequence variations. However, these studies examined only a few selected genes. To distinguish between these closely related isolates and better investigate ASFV evolution in Sardinia, we sequenced the complete genomes of 12 Sardinian ASFV isolates collected between 1978 and 2012, and compared them with 47/Ss/2008 and 26544/OG10. Most of the observed changes occurred in a time‐dependent manner; however, their biological significance remains unclear. As a whole, our results demonstrate the remarkable genetic stability of these strains, supporting a single‐source introduction of the virus.