dsRNA. To counteract this, many dsRNA genomes are constructed inside of capsids, thereby avoiding detection inside of the host cell's cytoplasm. mRNA is forced out from the capsid in order to be translated or to be translocated from a mature capsid to a progeny capsid. While dsRNA viruses typically have capsids, viruses in the families Amalgaviridae and Endornaviridae have not been observed to form virions and as such apparently lack capsids. Endornaviruses are also unusual in that unlike other RNA viruses, they possess a single, long open reading frame (ORF), or translatable portion, and a site-specific nick in the 5′ region of the positive strand. dsRNA viruses are classified into two phyla within the kingdom Orthornavirae of the realm Riboviria: All viruses in Duplornaviricota are dsRNA viruses. In Pisuviricota, all members of the class Duplopiviricetes are dsRNA viruses. Group IV: positive sense single-stranded RNA viruses The fourth Baltimore group contains viruses that have a positive sense single-stranded RNA (+ssRNA) genome. For +ssRNA viruses, the genome functions as mRNA, so no transcription is required for translation. +ssRNA viruses will also, however, produce positive sense copies of the genome from negative sense strands of an intermediate dsRNA genome. This acts as both a transcription and a replication process since the replicated RNA is also mRNA. The 5′-end may be naked, capped, or covalently bound to a viral protein, and the 3′-end may be naked or polyadenylated. Many +ssRNA viruses are able to have only a portion of their genome transcribed. Typically, subgenomic RNA (sgRNA) strands are used for translation of structural and movement proteins needed during intermediate and late stages of infection. sgRNA transcription may occur by commencing RNA synthesis within the genome rather than from the 5′-end, by stopping RNA synthesis at specific sequences in the genome, or by, as a part of both prior methods, synthesizing leader sequences from the viral RNA that are then attached to sgRNA strands. Because replication is required for sgRNA synthesis, RdRp is always translated first. Because the process of replicating the viral genome produces intermediate dsRNA molecules, +ssRNA viruses can be targeted by the host cell's immune system. To avoid detection, +ssRNA viruses replicate in membrane-associated vesicles that are used as replication factories. From there, only viral +ssRNA, which may be mRNA, enters the main cytoplasmic area of the cell. +ssRNA viruses can be subdivided between those that have polycistronic mRNA, which encodes a