Isolated specific IgA against respiratory viruses, Influenza or SARS-CoV-2, present in the saliva of a fraction of healthy and asymptomatic volunteers

Abstract Objectives: Defense against respiratory viruses depends on an immune response present in the mucosa, as saliva IgA secretes antibodies. During the pandemic, such as influenza or SARS-CoV-2, most infected patients are asymptomatic but retain specific antibodies post-infection. The authors evaluated IgG and IgA antibodies against SARS-CoV-2 and influenza in the saliva of asymptomatic volunteers, validated with controls or vaccinated individuals. Methods: The authors detected specific antibodies by validated conventional ELISA using natural SARS-CoV-2 antigens from infected Vero cells or capture-ELISA for influenza using natural antigens of the influenza vaccine. Results: Saliva from influenza-vaccinated individuals had more IgA than paired serum, contrary to the findings for specific IgG. In COVID-19-vaccinated samples, specific IgA in saliva increased after vaccination, but IgG levels were high after the first dose. In saliva from the asymptomatic population (226), anti-Influenza IgG was found in 57.5% (130) of samples, higher than IgA, found in 35% (79) of samples. IgA results were similar for SARS-CoV-2, with IgA present in 30% (68) of samples, while IgG was less present, in 44.2% (100) of samples. The proportion of influenza IgG responders was higher than that for SARS-CoV-2 IgG, but both populations presented similar proportions of IgA responders, possibly due to variable memory B cell survival. For both viruses, the authors found an important proportion (> 10%) of IgA+IgG- samples, suggesting the occurrence of humoral immunity directed to the mucosa. Conclusion: Specific antibodies for respiratory viruses in saliva are found in either infection or vaccination and are a convenient and sensitive diagnostic tool for host immune response.

Toxoplasmose em ovinos e caprinos: estudo soroepidemiológico em duas regiöes do Estado de Pernambuco, Brasil / Sheep and goat toxoplasmosis: soroepidemiological study in two regions in the State of Pernambuco, Brazil

Com o objetivo de comparar variáveis epidemiológicas na toxoplasmose em ovinos e caprinos, amostras de soro de animais de propriedades localizadas em duas regiöes do Estado de Pernambuco, Brasil, foram testadas pela reaçäo de imunofluorescência indireta (RIFI) para detecçäo de anticorpos anti-Toxoplasma gondii. Dos 173 soros ovinos testados, em 35,3 por cento foram encontrados resultados positivos, enquanto 40,4 por cento dos 213 soros caprinos foram positivos à RIFI. Em ovinos, associaçöes significativas foram encontradas para sexo e raça, mas näo para regiäo, tipo de manejo ou falha reprodutiva. Os resultados da RIFI para os caprinos foram significativamente associados ao sexo, raça, regiäo, tipo de manejo e de exploraçäo, mas näo com a ocorrência de falhas reprodutivas.