Zika virus dynamics in body fluids and risk of sexual transmission in a non-endemic area.

OBJECTIVE: To understand Zika virus (ZIKV) dynamics in fluids of infected individuals and the risk of sexual transmission. METHODS: Prospective study at two centres in Spain. Patients with probable or confirmed diagnosis of ZIKV infection were clinically followed up, and fluid samples were collected from saliva, serum, urine and semen or vaginal secretion following the study protocol. Non-traveller-sexual partners were offered to participate. RESULTS: From January 2016 to December 2016, we included a total of 11 traveller patients and six sexual contacts. Six patients were male, with a median age of 38 years (IQR 30-45). We performed 61 RT-PCR determinations, seven of which were positive. Positive results were retrieved from serum, urine, semen and vaginal tract. One of four women tested positive for ZIKV RNA in vaginal swabs collected during the first 45 days after symptoms onset. Clearance occurred between day 37 and day 69 after symptoms onset. One of five men tested positive for ZIKV RNA in semen collected during the first 45 days after symptoms onset. Clearance occurred between day 23 and 107 after symptoms onset. Six patients had sexual relations during the defined period. All tested patients were negative for ZIKV infection by serological testing. CONCLUSION: ZIKV shedding persistence in genital fluids occurs in a significant number of symptomatic patients after visiting an endemic area. We did not find any ZIKV seroconversion among the three male contacts who were investigated. Diagnostic algorithms may be updated to include genital tract fluid specimens in the diagnostic process.

Viruses within animal genomes.

Viruses and their hosts can co-evolve to reach a fragile equilibrium that allows the survival of both. An excess of pathogenicity in the absence of a reservoir would be detrimental to virus survival. A significant proportion of all animal genomes has been shaped by the insertion of viruses that subsequently became 'fossilised'. Most endogenous viruses have lost the capacity to replicate via an infectious cycle and now replicate passively. The insertion of endogenous viruses has contributed to the evolution of animal genomes, for example in the reproductive biology of mammals. However, spontaneous viral integration still occasionally occurs in a number of virus-host systems. This constitutes a potential risk to host survival but also provides an opportunity for diversification and evolution.

Les virus et leurs hôtes ont démontré leur capacité à co-évoluer pour atteindre le fragile équilibre qui assure leur survie mutuelle. Une pathogénicité excessive sans réservoir disponible peut compromettre la survie d'un virus. Un nombre proportionnellement significatif de génomes animaux ont vu leur structure modifiée par l'insertion de virus qui se sont par la suite « fossilisés ¼. La plupart des virus endogènes ayant perdu leur aptitude à se répliquer via le déclenchement d'un cycle infectieux, leur réplication s'effectue désormais de manière passive. L'insertion de virus endogènes dans les génomes animaux a contribué à les faire évoluer, comme l'illustre la biologie de la reproduction des mammifères. Néanmoins, des intégrations spontanées de virus continuent de se produire ponctuellement dans certains systèmes virus-hôtes. Elles représentent un risque potentiel pour la survie de l'hôte mais ouvrent également de nouvelles perspectives de diversification et d'évolution.

Los virus y sus anfitriones pueden coevolucionar hasta alcanzar un frágil equilibrio que permite la supervivencia de ambos. A falta de un reservorio, una patogenicidad excesiva resultaría perjudicial para la supervivencia del virus. Hay una proporción importante de todos los genomas animales en cuya configuración ha intervenido la inserción de virus, ulteriormente «fosilizados¼ en el genoma. La mayoría de los virus endógenos han perdido la capacidad de replicarse por medio de un ciclo infeccioso y se replican ahora de forma pasiva. La inserción de virus endógenos ha contribuido a la evolución de los genomas animales, por ejemplo en la biología reproductiva de los mamíferos. No obstante, en muchos sistemas virus-anfitrión se sigue dando ocasionalmente una integración vírica espontánea, lo que supone a la vez un posible riesgo para la supervivencia del anfitrión y una oportunidad de diversificación y evolución.